“Docket No. 80-2848 SECRETARY OF LABOR,Complainant,v.COLLIER-KEYWORTH COMPANY,Respondent.OSHRC DOCKET NO. 80-2848ORDERBefore: BUCKLEY, Chairman, and AREY, Commissioner.BY THE COMMISSION:The parties reached a settlement agreement during appeal proceedings in this case inthe United States Court of Appeals for the First Circuit. The court dismissed the appealin accordance with the joint motion of the parties reciting the existence of thesettlement agreement. McLaughlin v. Collier-Keyworth Company, No. 88- 2140 (1st Cir.,March 22, 1989). In its mandate, the court stated:The case is remanded to the Occupational Safety and Health Review Commission withinstructions to vacate its decisions and orders in this case in accordance with thesettlement agreement…..In accordance with that mandate, the Commission’s order and decision in this case arevacated. Part 1 (a) of the citation for violation of 29 C. F. R. ? 1910.95 (a) isaffirmed. Parts 1 (b) and 1 (c) of the citation for violation of 29 C. F. R. ? 1910.95(b) are vacated. No penalty is assessed.FOR THE COMMISSIONRAY H. DARLING, JR.EXECUTIVE SECRETARYDATED: April 27, 1989SECRETARY OF LABOR,Complainantv.COLLIER-KEYWORTH COMPANYRespondentOSHRC Docket No. 80-2848THE REMANDThe Review Commission remanded this case to the Administrative Law Judge \”toafford the Secretary an opportunity to rebut officially-noticed documents with evidence ofthe Secretary’s intent when he adopted the standard\” at29 C. F. R. ? 1910.95 a-b in 1969. [Emphasis added]The Administrative Law Judge is directed to propose \”a supplemental decisionaffirming, modifying or vacating those citation items relevant to the impulse noise issuein light of any additional evidence that the parties submit.\”Part of the Review Commission’s decision reads as follows: \”…the record in thiscase contains evidence of events leading up to the adoption of the Walsh-Healey standard…. The parties presented witnesses…who were personally familiar with many of theevents leading up to the standard’s adoption. This testimony is supplemented bydocumentary exhibits introduced by the parties and other documents that we officiallynotice …. The documents we officially notice include only Labor Department publicationsand scientific papers cited in documents that were introduced into evidence … Ourpurpose in taking official notice is not to determine whether impulse noise is harmful orwhether the pre-ponderance of scientific thinking in 1969 would have favored theregulation of impulse noise under Table G-16 …. Our purpose is instead to determine theintent of the Secretary in 1969 by examining the body of knowledge on impulse noise thatinfluenced the adoption of the standard. Because our decision rests in part on theseofficially noticed documents, we shall afford the Secretary an opportunity to rebut themwith documents and other evidence of his intent when he adopted the standard.\”[Emphasis provided]…Review Commission decision, pages 14, 15.History-of-the-StandardThe Technical Committee on Noise of the American Industrial Hygiene Association [AIHA]suggested a committee of noise experts to recommend guidelines. The Labor Departmentagreed, and the Inter-Society Committee on Guidelines for Noise Exposure Control came intobeing. The so-called Inter-Society Committee had two members from each of five technicalsocieties: the AIHA, the ACGIH [American Conference of Governmental IndustrialHygienists], the American Academy of Ophthalmology and Otolaryngology, the AmericanAcademy of Occupational Medicine, and the Industrial Medical Association. Herbert H. Joneswas Chairman of the ACGIH and one of the ACGIH representatives was Van Atta who, accordingto Jones, had primary responsibility in the noise area for the Labor Department ….The inter-Society Committee report [1967] had criteria for only \”steady\”noise [which would be non-impulsive noise].Later ACGIH proposed a standard, and in the proposal it twice stated that its proposedlimits would \”not apply to impulse or impact type of noise.\”The Review Commission pointed out that \”the criteria proposed by both theInter-Society Committee and the ACGIH committee excluded impulse noise, with the exceptionof the ACGIH proposal for a peak limit of 140 dB for impulse noise…On September 20, 1968, the Labor Department published a proposed standard to regulateworkplace noise exposure. 33 Fed. Reg. 12458, 14259-60. This proposed standard bore verylittle resemblance to the present standard… and included impulse noise in its exposurecalculations.And on January 17, 1969, the Labor Department issued a Walsh-Healey noise standard verysimilar to that which had been proposed and retaining the provision on impulse noise.However, this proposal standard was stayed by the Secretary of Labor … 34 Fed. Reg.2207.On May 20, 1969, the Labor department issued a new standard that (in the words of theReview Commission) \”is identical to the one at issue in this case. Major differencesbetween the earlier standard and the later standard include provisions relevant to theimpulse noise issue. The earlier standard explicitly stated that … impulse noise was tobe included in weekly exposure calculations. However, the final standard contained nosimilar provision and included a provision with no counterpart in the earlier standard–arecommended limit of 140 dB for impulse noise.\”The Review Commission concluded that: \”The final standard strongly resembled thatadopted by the ACGI: on May 12, 1969 …\”….. Review Commission, 15-21.To summarize the Review Commission’s apparent analysis: On September 20, 1968, theLabor Department’s proposed standard included impulse noise in its exposure calculations.And on January 17, 1969, the Labor Department proposed a standard that retained theprovision on impulse noise, but the Secretary of Labor stayed it.Then on May 20, 1969, the Labor Department issued a standard that had no provisionincluding impulse noise in exposure calculations but had a recommended limit of 140 dB forimpulse noise.The Review Commission also said: \”Jones was still Chairman of the ACGIH Committee;he stated that Dr. Van Atta of the Labor Department had been aware of the wordings of theCommittee and of its proposed standard…\” … Review Commission decision 21.As the Review Commission pointed out, the standard must be given the same meaning ithad under the Walsh-Healey Act … Review Commission decision 14.The Labor Department’s Bulletin 334 of December 4, 1970, revised on June 8, 1971,indicates that the Secretary was aware of the scientific reasons why impulse noise isexcluded from the standard… Review Commission decision 27. It is also consistent withthe Review Commission’s finding that the evidence is overwhelming that OSHA interpretedthe standard to exclude impulse noise from Table G -16… Review Commission decision 32.The Remand TranscriptBecause the Remand was heard at various dates, the four volumes of the RemandTranscript are herein designated by the roman numerals I, II, III, and IV preceding thepage number.Scope of the RemandIn addition to the usual rules of evidence, the testimony and evidentiary exhibits werefurther restricted by the parameters of the Review Commission’s Remand order: \”…..evidence of the Secretary’s intent when he adopted the standard in 1969.\”Excluded EvidenceThere were several rejected proffers of evidence, However, even if any or all of suchevidence had been admitted, it was not of sufficient weight or credibility to affect anyfinding or the decision.The IssueThe question on Remand is not whether employees are better protected if impulse\/impactnoise is included in determining if the limitations imposed by the table G-16 wereexceeded; it is rather to determine whether the Secretary of Labor intended to haveimpulse\/impact noise included in table G-16, for whatever reasonsFindings and ConclusionsI have considered the briefs and the Respondent’s 161 proposed findings of fact andconclusions of law. To the extent shown herein these are adopted; otherwise, they arerejected as not being supported by the evidence or law or as being immaterial orirrelevant or beyond the scope of the Order of Remand.Testimony at Remand HearingFour witnesses testified at the Remand Hearing: Davis, Kamperman, Ward and Hildyard.Part of their testimony is summarized below.[1] Irving DavisDavis, a retired industrial hygiene engineer, was involved in sampling employeeexposure to noise in Michigan, and dealt predominantly with the Michigan noise standard(I, p.16,17). He was a member of the American conference of Governmental IndustrialHygienists (\”ACGIH\”) since the early 1950’s and was appointed to the PhysicalAgents Committee from 1967 to the present. Davis was also a member of the AmericanIndustrial Hygiene Association in 1969 and 1971. (I, p.19-20)Davis’ testimony revealed that all work places had a mix of steady-state andimpact\/impulse noise (I. p.18, 36) and that the threshold limit value included all noise;he stated that impulse\/impact noise should not and could not be practically edited from anoise survey (I, p.36). Further, that the intent of the noise standard proposed by theACGIH committee in 1968 (Review Commission Decision, Appendix, P.57) was that it did notapply to \”peak\” measurements of impact or impulse noise. It did not mean thatimpact or impulse noises should be edited or excluded from the total noise measurement (I,p.27-28). Although Davis agreed that the qualifying term \”peak\” did not appearin his committee’s definition of impulse\/impact and continuous noise \”we understoodthat to be ‘peak’.\” (I, pp. 75-76). However, he testified only to his \”personalunderstanding\” of this; Davis could refer to no written evidence of thisinterpretation (I, pp. 27-28). He was unable to provide any state or federal OSHA noisestandard interpretation, or any documents relating to impulse noise measurements (I, pp.78-79).Similarly, Davis was aware of the statement in Bulletin 334 of the Department of Labor(R66 of Review Commission Decision) which explained, in part, that \”[i]n contrastwith 115 dBA upper limit for steady noise, the higher intensity for impact noise ispermissible because noise impulse resulting from impact… is passed before the ear hastime to react fully.\” He understood that this was based on available scientific andmedical evidence, but that his personal understanding of this was that it was intended toapply only to peak sound pressure (I, p. 147-148). In contrast, at his deposition, Davisdid not limit his answer to \”peak\”, stating that he understood that allimpulse\/impact sound did not reach the inner ear (I, p.148)In R11, a copy of The Physical Agents Committee’s document referring to the valuesexpressed in the ACGIH TLU, it states that \”[t]hese values … [do] not apply toimpact or impulse type of noises.\” Davis understood this to mean \”peak\”measurements of impact or impulse noise (I, p.183).Davis was not involved in any Department of Labor meetings concerning the development offederal OSHA standards (I, p.117-118). He never discussed the noise standard or impulsenoise with Van Atta (I, p.119). He did not participate or have personal knowledge of whatwent in to the promulgation of the Occupational Noise Standards under Walsh-Healey (I,p.120) nor was he involved in the Inter-Society Committee (I, p.104).Davis was unaware of any Department of Labor documents, from 1968 to 1970 thatdiscussed the interpretation of the noise standard and whether impact\/impulse noise was orwas not required to be included for enforcement purposes, nor did he discuss the subjectwith OSHA personnel (I, p.137). However, his office received \”CPL’s\” (documentsintended to provide interpretations of Federal OSHA standards) throughout the 1970’s (I,p.173-174).[[2]] George KampermanKamperman, a consulting engineer in noise control and sound level meters, was a memberof several American National Standards Institute (ANSI) committees, one of which studiedthe performance characteristics and capabilities of sound level meters (I, p.194; II,p.223).The focal point of Kamperman’s testimony involved a June 11 and 12, 1969 symposium onindustrial noise, which was held to discuss the implications of the Walsh-Healey Act whichhad been promulgated in May, 1969. (II, p.244).Dr. Floyd Van Atta, from the Department of Labor, was invited to speak, as he wasconsidered the \”architect\” of the noise regulation standard in the Walsh- HealeyAct (II, p.245-246). He discussed the background of the new noise standard and how it wasto be enforced by the Department of Labor (II, p.247). Panel discussions were held andKamperman engaged in informal discussions with Van Atta at the time (II, p. 247, 263).Kamperman’s basis for testifying to Van Atta’s position with respect to impulse\/impactnoise was founded on four such informal meetings, two taking place at dinners on theevenings before each day’s symposium meeting (II, p.248), and two other seminar meetings,the date and location of which Kamperman could not recall (II, p.324-325).Throughout his testimony, Kamperman stated what he remembered to be Van Atta’s position(thus, the Department of Labor’s) with respect to the Walsh-Healey noise standard, whichhe gleaned from informal meetings and Van Atta’s symposium presentation. He recalled thatVan Atta believed that all noise in an industrial environment, including impact\/impulsenoise, was to be in the Table G-16 computation, and that there was an additionalrequirement that impact\/impulse noise not exceed 140 dB peak sound pressure (II.p.249,253,262,268,275,278).However, Kamperman had never seen a document or official agency interpretation,including OSHA CPL’s for noise standards or noise measurement, nor any other writteninterpretation for the Department of Labor, or OSHA, instructing employers to includeimpulse noises in Table G-16 when making noise measurements (II, p.305,354,360,361). Thehandouts at the symposium did not cover impact\/impulse noise or its computation underTable G-16 (II, p.295-296). Kamperman could not recall Van Atta’s opening or closingremarks of his speech and could not quote anything that Van Atta said during the two-daysymposium (II, p.318). Kamperman stated that he was not a \”careful note taker\”;he took no notes of Van Atta’s speech and knew no one who did (II, p.290, 321, 335).Kamperman could not recall any specific statements by Van Atta about the source of theWalsh-Healey noise standard (II, p.328), nor was he aware of any of Dr. Van Atta’swritings (II, p.346).Kamperman stated at his deposition that he was \”not capable of recalling things\” (II, p. 335). He had never worked with Van Atta on a day-to-day basis (II, p.360).[3] W. Dixon WardWard, a professor at the University of Minnesota, teaches, consults and does researchin the field of noise and its effects on humans and animals (II, p.365). In the 1950’s and60’s, his research dealt with the effects of impulse noise (II, p.368). Ward was chairmanof the working group of the Committee on Hearing Environmental Acoustics which put out aproposed damage risk criteria for impulse noise in 1968.Ward’s testimony indicated that, as of 1969, there is no sound, scientific basis forexcluding the impulse noise component from the total worker noise exposure calculationused to protect hearing; both steady-state and impact noise are potentially hazardous inan industrial environment (II, p. 380, 381, 384, 396),. However, he also noted that before1971, there were scientific studies that indicated impact\/impulse noise situations shouldbe treated separately from continuous or steady- state noise (III, p.62). Hisunderstanding of the original OSHA noise standard was that its permissible exposure levelfor non-impulse noise at 90 for an eight hour duration is less than or equal to 140 dBpeak for impulse noise regardless of its duration (II, p.448-449). Ward was not aware ofany documents that interpreted how impact noise was to be treated under the OSHA noisestandard (III, p.158-160)Ward had no personal participation or knowledge of the promulgation processes, eventsor discussions that resulted in both the Walsh-Healey or OSHA noise standards (II, p.370,448; III, p. 31-33). He was not familiar with Dr. Van Atta’s writings until this hearing(II, p.449). Ward had never had discussions with Van Atta concerning impact\/impulse noiseor its measurement under Table G-16 (III, p.46). He was unfamiliar with the identities ofany of the draftsmen for the Walsh-Healey or OSHA noise standards (III, p.33).[4] Victor HildyardHildyard, a physician and surgeon and specialist in otology, had encountered theeffects of impact\/impulse noise in clinical practice. He was appointed by Undersecretaryof Labor Guenther to be chairman of the OSHA Standards Advisory committee in 1972 (III,p.196). The fifteen-person committee, which met in 1973, in meetings open to the public,reviewed and evaluated noise standards relating to permissible levels of exposure,reviewed the history of the criteria documents that led up to the original noise standardof OSHA and Walsh-Healey, collected information on new research and development performedsince the original standard and made recommendations to the Secretary of Labor for arevised noise standard (III, p.196, 218, 219). Dr. Van Atta, as a representative of theDepartment of Labor, was an advisor to the committee (III, p. 196), and as such, outlinedthe course and objectives of the group, and assisted in tracing the history of thestandards (III, p.234-235, 219). Van Atta would prepare and edit the Committee’srecommendations into a final draft to be sent to the Secretary of Labor (III, p.229). VanAtta was present, as advisor, at every committee meeting (III, p.230).Hildyard had numerous private discussions with Dr. Van Atta in 1973 concerning theinclusion or exclusion of impulse noise from Table G-16 (IV, p.232, 280). At the time, Dr.Van Atta expressed the Department of Labor’s position with respect to permissible noiselevel exposure for continuous noise, worker protection, and impulse noise (IV, p.232-233).It was the Department of Labor’s position, as expressed by Van Atta, that impulse noisecould not be included in Table G-16, as impact\/impulse noise and continuous noise were tobe measured separately and had distinct damage risk criteria; impulse noise could not beintegrated into the Table, or the threshold limit values, or the permissible noise valuesfor continuous noise (IV, p.235-236, 280, 281, 283). In addition, the departmentalposition, according to Van Atta, and based on ACGIH conclusions and studies, was that thehuman ear treats these two types of noises differently (IV, p. 235, 237-239). Dr. Van Attastated that the Department of Labor’s position was that if a worker stayed within thepermissible limits of 140 dB peak for impulse noise, for a working day over a workinglifetime, his hearing would not be in any danger (IV, p.239- 240). Hildyard testified thatVan Atta stated that, in 1969, the Department of Labor intended to treat impulse noisedifferently from continuous noise, as he used the Walsh- Healey standard as a startingpoint for the Committee to continue its work(IV, p. 237, 255, 282). Van Atta’s position in 1973 was the same as it was in 1969 (IV, p.282).The Secretary of Labor’s representativeAll the facts, and the inferences to be drawn from them, indicated quite clearly thatthe Secretary of Labor was represented by Van Atta, a Labor Department employee whoparticipated in proceedings pertaining to the noise standard in question. In fact, theComplainant stipulated that Van Atta was (in 1973):\”…. an employee of theDepartment of Labor and he was at this committee meeting in his official capacity…\”… Tr. IV 251. And both sides, at one time or another, took the position that Van Attarepresented the Secretary of Labor in matters pertaining to the noise standard.DiscussionAn analysis of the testimony of each of the four witnesses who testified on remand[Davis, Kamperman, Ward, and Hildyard] makes it clear that the decision on remand must belargely based on a choice of relying on either the memory of Kamperman or that ofHildyard. That is because the best evidence of the intent of the Secretary of Labor–thestated aim of the hearing on remand–would be best disclosed by the conduct and statementsof the Secretary’s representative (van Atta). Of the four, only Kamperman and Hildyardgave specific instances of such conduct and statements by van Atta. Should one be reliedon more than the other?I find that both Kamperman and Hildyard were extremely well qualified in their fieldsof expertise; and I find that both were equally candid and honest in their testimony.I find that both have tried equally hard to recall events that happened many yearsbefore the hearing. However, I find that the memory of Hildyard was more likely to recallspecific details of conduct and statements by van Atta because, as Chairman of theCommittee to which van Atta was advisor, Hildyard would in all probability have had morecommunications with van Atta, and more reason to pay attention to van Atta’s statementsand conduct, than Kamperman or other committee members. For primarily that circumstance, Ifind that the memory of Hildyard is to be relied on more than anyone else’s when [as here]it is a question of great concern to the committee he chaired.I find that, when the standard in question was adopted in 1969, it was the Secretary ofLabor’s intent that impact\/impulse noise should not be included in table G-16.Accordingly, as the Review Commission said in its decision of April 6, 1987, which isfollowed and affirmed by the undersigned: \”….. we vacate citations item 1a (B) and(D), and ib (b) and (D) …… We vacate items 1a (A) and (C) … And we vacate items 1b(A) and (C).\”SO ORDERED.Recommendation Regardless of the ultimate outcome of this case, no tribunal concerned with justice anddue process of law should tolerate a potential situation where neither the Complainant northe Respondent can be reasonably certain of exactly what a standard mandates. The meaningof its words should not have to be determined by implication or interpretation orspeculation or guesswork.And certainly a standard should not be so worded that it possibly could call for theuse of tools or implements or testing methods that necessarily result in erroneousmeasurements or conclusions. Unfortunately, the standard here is subject to such flaws.The Labor Department is strongly urged to take the necessary steps to have the standardbe amended or re-worded so that its meaning is crystal clear to all who may be concernedin its enforcement.FOSTER FURCOLOJudge, OSHRCDated: August 24, 1988Boston, MassachusettsSECRETARY OF LABOR,Complainant,v.COLLIER-KEYWORTH COMPANY,Respondent.OSHRC Docket No. 80- 2848ORDER OF REMANDOn April 6, 1987, the Commission issued a decision holding that Table G-16 of theoccupational noise standard at 29 C. F. R. ? 1910.95 (a)-(b) did not cover impulse noise.The Commission based its holding on the language of the standard, its legislative historyand the Secretary’s interpretation of the standard shortly after its adoption. In weighingthe legislative history of the standard and the Secretary’s interpretation of the standardshortly after its adoption, we referred to documents that we officially noticed undersection 7 (d) of the Administrative Procedure Act, 5 U. S. C. ? 556 (e). We also statedthat we would afford the Secretary the opportunity to rebut the officially-noticeddocuments with documents and other evidence of his intent when he adopted the standard in1969. The Commission therefore ordered that certain citation items be vacated unless theSecretary requested an opportunity within 15 days to rebut officially-noticed documents.The Secretary has filed a motion for an extension of time to gather, review andpossibly submit documents relevant to the intent of the standard’s drafters with respectto the coverage of impulse noise. The Secretary asks for extension of three weeks, throughMay 11, 1987. Ordinarily, we would simply grant this motion, for it is supported by goodcause. In this case, however, the Secretary’s motion would, if granted, cause the periodof time to extend beyond the term of one of the Commission’s two current members. TheCommission might for some time therefore be unable to directly act on further motions inthe case and might be unable to remand the matter to the administrative law judge toreceive further documents and supporting testimony. Inasmuch as this issue is an importantone and should be expeditiously resolved, we will grant the motion and remand this case tothe administrative law judge now with instructions to afford the Secretary an opportunityto rebut officially-noticed documents with evidence of the Secretary’s intent when headopted the standard in 1969. The judge shall expeditiously prepare supplemental decisionaffirming, modifying or vacating those citation items relevant to the impulse noise issuein light of any additional evidence that the parties submit. If the Secretary does notdesire that the record be re-opened, the judge shall issue a decision vacating thecitation items in accordance with our decision of April 6, 1987.Accordingly, this case is remanded to the administrative law judge for furtherproceedings.FOR THE COMMISSIONRay H. Darling, Jr.Executive SecretaryDATED: April 22, 1987SECRETARY OF LABOR,Complainant,v.COLLIER-KEYWORTH COMPANY,Respondent.OSHRC Docket No. 80-2848DECISION Before: BUCKLEY, Chairman; WALL, Commissioner.BY THE COMMISSION:This case is before the Occupational Safety and Health Review Commission under 29 U. S.C. ? 661 (j), section 12 (j) of the Occupational Safety and Health Act of 1970, 29 U. S.C. ?? 651- 678 (\”the Act\” or \”the OSH Act\”). The Commission is anadjudicatory agency, independent of the Department of Labor and the Occupational Safetyand Health Administration (\”OSHA\”) It was established to resolve disputesarising out of enforcement actions brought by the Secretary of Labor under the Act and hasno regulatory functions. See section 10 (c) of the Act, 29 U. S. C. ? 659 (c).I IntroductionCollier-Keyworth Company manufacturers swivel and tilt mechanisms for office chairs ina plant in Gardner, Massachusetts. In April 1980, OSHA industrial hygienists inspectedCollier- Keyworth’s plant to determine whether the company was in compliance with theoccupational noise standard at 29 C. F. R. ? 1910.95 (a)-(b). From measurements madeduring the inspection, OSHA concluded that employees who operated power presses and lathesat the plant were exposed to noise in excess of the limits established by the standard. Ittherefore cited Collier-Keyworth for various violations of section 1910.95. At the time ofthe alleged violations, the standard provided:[[1]]? 1910.95 Occupational noise exposure.(a) Protection against the effects of noise exposure shall be provided when the soundlevels exceed those shown in Table G-16 when measured on the A scale of a standard soundlevel meter at slow response.(b) (1) When employees are subjected to sound exceeding those listed in Table G-16,feasible administrative or engineering controls shall be utilized. If such controls failto reduce sound levels within the levels of Table G-16, personal protective equipmentshall be provided and used to reduce sound levels within the levels of the table.(2) If the variations in noise level involve maxima at intervals of 1 second or less,it is to be considered continuous.(3) In all cases where the sound levels exceed the values shown herein, a continuing,effective hearing conservation program shall be administered.Table G-16–Permissible Noise Exposures [[1]]Sound level dBADuration per day, hours\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 slow response8…………………………………………………………………………………………………………..906…………………………………………………………………………………………………………..924…………………………………………………………………………………………………………..953…………………………………………………………………………………………………………..972…………………………………………………………………………………………………………10011\/2……………………………………………………………………………………………………1021…………………………………………………………………………………………………………1051\/2………………………………………………………………………………………………………1101\/4 orless……………………………………………………………………………………………115[[1]] When the daily noise exposure is composed of two or more periods of noise exposureof different levels, their combined effect should be considered, rather than theindividual effect of each. If the sum of the following fractions: C1\/T1 + C2\/T2)[+………] Cn\/Tn exceeds unity, then, the mixed exposure should be considered to exceedthe limit value. Cn indicates the total time of exposure at a specified noise level, andTn indicates the total time of exposure permitted at that level.Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.The principal dispute in this case is whether Table G-16 regulates a kind of noisecalled \”impulse noise.\” The dispute arises in this case because, in determiningwhether Collier-Keyworth’s employees were exposed to more noise than Table G-16 permits,OSHA employed measuring devices-sound level meters and personal noise dosimeters–thatregistered impulse noises in Collier- Keyworth’s plant. Collier-Keyworth argues that TableG-16 was not intended to regulate impulse noise and therefore that OSHA’s measurementswere unreliable.A. Measuring Noise Exposure Under Table G-16Before we set out and discuss these arguments, we shall discuss generally the twomethods of proving that an employer has violated the limits for noise exposure in TableG-16 of section 1910.95 (a)-(b). First, the Secretary may show that an employee issubjected to a sound level equal to or greater than a level listed in Table G-16 for alonger period of time than the table permits. For example, the Secretary could meet hisburden of proof by showing that an employee is exposed to 92 dBA or higher for more thansix hours, or to 105 dBA higher for more than one hour. If this method is used, however,sound levels that last for less than their permissible periods would have to bedisregarded. Yet, sound levels in industrial plants often fluctuate and continue for lessthan their permissible periods; some last for only a few minutes or seconds. This methodtherefore can result in a substantial underestimate of an employee’s total noiseexposure.[[2]]The second way in which the Secretary can show overexposure overcomes this difficultybut introduces others. The second method uses the cumulation formula in the footnote toTable G-16. This formula explains how one may calculate an employee’s noise dosage whensound levels vary throughout the workday. Under the cumulation formula, a fraction, Cn\/Tn(Cn being the time the employee is exposed to that level and Tn being the exposure timepermitted at that level), is calculated for each different noise level to which anemployee is exposed during the workday. At the end of the day, all the fractions thuscalculated are added together. If the total is more than one (\”unity\”), theemployee has been exposed to noise exceeding permitted limits.The cumulation formula yields a more accurave determination of an employee’s totalnoise exposure, for it counts as part of the employee’s noise exposure sound levels thatcontinued for less than the permissible period. This permits each variation in noise levelto be given its proper weight and to be cumulated. However, the cumulation formula isconsiderably more difficult to apply. An OSHA compliance officer must hold the microphoneof a sound-level meter in an employee’s hearing zone; read each different sound levelregistered on the meter; with a watch, determine the duration of that level; and record ona notepad each sound level and its duration. Where the noise level is constantly varying,however, it is extremely difficult to manually make the many measurements and calculationsnecessary to apply the formula. And, because the task is so difficult to performaccurately, compliance officers cannot survey the exposure of more than a few employees ina day.To overcome these problems, the personal noise dosimeter was developed. The dosimeteris an electronic instrument that contains the circuitry of a standard sound level meteralong with other circuitry. A dosimeter is small enough to be worn by an employeethroughout the workday as he goes about his duties. The dosimeter microphone, which ispart of the dosimeter’s sound level meter, is placed in the employee’s hearing zone, whereit continually detects the noise to which the employee is subject. The sound level metercircuitry within the dosimeter measures the varying sound levels and sends thatinformation to the other dosimeter circuitry, which automatically calculates and sums thefraction as required by the cumulation formula.[[3]] At the end of the workday, thedosimeter gives a reading in terms of the percentage of the permitted daily dosage adosimeter reading of 100 percent means that the sum of the fractions is one. A dosimeterreading exceeding 100 percent thus means that the permitted daily noise dosage has beenexceeded. See New England Container Co., 84 OSAHRC 55\/A2, 12 BNA OSHC 1368,1371 n. 7, 1984-85 CCH OSHD (P) 27,148, pp. 35,045-46 n. 7 (No. 78-1539, 1984).The Secretary measured the noise exposure of Collier-Keyworth’s employees usingdosimeters. Because the dosimeters indicated that Collier-Keyworth’s power press and latheoperators were exposed to more than 100 percent of the permitted daily dosage. TheSecretary alleges that the employees were exposed to noise exceeding the limits permittedby the standard. Collier-Keyworth contends that the dosimeter readings cannot be reliedupon to find overexposure. The company raises a number of potential inaccuracies withdosimeters, but its principal argument is that the dosimeter readings obtained by theSecretary were unreliable because some of the noise they measured was impulse noise, atype of noise the company argues is not intended to be included in dosage calculationsunder Table G-16.B. Impulse NoiseImpulse noise is noise of brief duration produced by a short-lived physical phenomenon,such as a gunshot, a clap of thunder, or a power press stroke. When such noise arises fromthe impact of two objects, it is called impact noise. The distinction between impact noiseand other impulse noise is not important to the issues before us. A provision of thestandard, however, requires that we distinguish between impulse noises based on the timebetween their peaks or maxima. Subsection 1910.95 (b) (2) states that \”[i]f thevariations in noise level involve maxima at intervals of 1 second or less, it is to beconsidered continuous\”. This provision reflects that much industrial noise consistsof level of repetitive impulses and that the impulses are often spaced so closely togetheras to sound continuous. One witness gave the example of a gearbox, in which noiseoriginates as the impact of gear teeth on gear teeth but the impacts occur so frequentlythat the ear does not hear the individual impacts. Subsection (b) (2) provides a criterionfor classifying closely-spaced impulse noise as continuous noise. Concomitantly, expertwitnesses for both parties testified that noise is considered to be \”impulsenoise\” if it involves maxima that are less than one second in duration and more thanone second apart.Collier-Keyworth’s arguments focus both on the words of the standard and itsbackground. Collier-Keyworth points to a provision that is now printed as the secondparagraph of the footnote to Table G-16. That provision states that \”[e]xposure toimpulsive or impact noise should not exceed 140 dB peak sound pressure level.\”Collier-Keyworth argues that this provision demonstrates that the standard treats impulsenoise differently from other noise. It also points to subsection (b) (2) of the standard.Because the one second interval mentioned in that subsection corresponds to the intervalthat is universally recognized as the dividing line between impulse noise and continuousnoise. The company contends that this represents the standard’s intent to draw a linebetween impulse noise and continuous noise, with the latter regulated by Table G-16calculation and the former excluded. It also relies on various documents and testimony tosupport its argument that, when the noise standard was adopted, the Secretary did notintend to regulate impulse noise under Table G-16.Administrative Law Judge Foster Furcolo agreed with Collier-Keyworth’s argument thatTable G-16 was not intended to cover impulse noise. On that basis, the judge vacated thecitations in their entirety. We agree with the judge’s conclusion that impulse noise mustbe excluded when determining whether Table G-16 limits have been exceeded. We further findthat the employees covered by items 1a(B) and 1b(B) and (D), of the citation were exposedto considerable\u00a0 amounts of impulse noise, and as to those employees the Secretarydid not prove overexposure to continuous noise. Employees covered by citation items 1a (A)and (C), and 1b (A) and (C), however, were exposed to noise defined as continuous bysubsection (b) (2) of the standard, i.e., to noise with impulses occurring more frequentlythan once per second. Although we find that the Secretary proved that those employees wereexposed to noise exceeding permitted limits, we also find that the Secretary did not showthat Collier-Keyworth failed to take the steps required by the standard to protect theemployees. We therefore affirm the judge’s disposition vacating all citation items.II. Does Table G-16 Cover Impulse Noise?The record establishes, as we shall discuss more fully later, that at least some of thenoise measured during OSHA’s inspection of Collier-Keyworth’s plant was impulse noise,that is, noise with sharp energy peaks lasting less than one second and spaced more thanone second apart. If Table G-16 does not regulate impulse noise-or, stated differently, ifimpulse noise must be excluded from the calculation of dosage when one uses the cumulationformula in Table G-16–then dosimeter readings that include impulse noises producereadings that are too high. Therefore, in determining whether the readings obtained byOSHA show that Collier-Keyworth’s employees were exposed to excessive noise, we must firstaddress Collier-Keyworth’s argument that section 1910.95 (a)-(b) does not intend forimpulse noise to be included in dosage calculations employing Table G-16 limits. [[4]] A. The Scope of Our InquiryThe Secretary contends that Collier-Keyworth’s argument should be rejected because therecord compiled in this litigation \”contains substantial expert testimony thatimpulsive …….. noise is no less damaging to hearing than continuous noise.\” TheSecretary cites the testimony of several witnesses, including that of a physicianspecializing in otolaryngology, and argues that the degree of permanent hearing loss isdirectly proportional to the amount of acoustic energy transferred to the ear.[[5]] TheSecretary reasons that because the energy associated with prolonged exposure to impulsenoise can cause irreversible hearing loss, it should be regulated by Table G-16.We do not dispute that there is now reason to believe that impulse noise can cause hearingloss. But in the absence of an OSHA standard, we do not have the authority to regulateexposure to impulse noise. New medical and scientific. evidence is not relevant if, asCollier-Keyworth claims, the Secretary did not intend Table G-16 to cover impulse noisewhen he adopted it. As an adjudicative body, the Commission must take the standard as itfinds it and apply the standard in accordance with the Secretary’s intent at the time ofpromulgation. See Oscar Mayer & Co. v. Evan, 441 U. S. 750, 758 (1979) (intent ofCongress that enacted statute is controlling). The Commission has no authority to\”update\” any standard through interpretation according to the latest scientificfindings. Such legislative authority resides in the Secretary, who, in rulemaking, mayconsider whether new findings about physical agents make regulation necessary and what newduties should therefore be imposed on employers. For the Commission to interpret astandard to produce what it believes will be greater protection for employees than theSecretary originally intended both usurps the Secretary’s rulemaking authority anddetracts from the statutory right of those affected by a rule to participate in therulemaking process.B. The Language of Section 1910.95 (a)-(b)The Secretary argues that the plain language of the standard indicates that he intended toregulate impulse noise under Table G-16. He notes that section 1910.95 (a) requiresprotection whenever \”sound levels\” exceed Table G-16 values, and argues that theall-inclusive phrase \”sound levels\” draws no distinction between impulse noiseand non-impulse noise.Standards must, however, be read as a coherent whole, and Collier-Keyworth points to twoprovisions it contends indicate an intent to exclude impulse noise from Table G-16.Collie-Keyworth points to the statement, now printed as the second paragraph of thefootnote to Table G-16, stating that exposure to peak sound pressure levels of impulsenoise should be limited to 140 dB. It argues that this special provision for impulse noiseshows an intent to treat impulse noise differently from other noise. The Secretary, on theother hand, contends that this provision demonstrates that where the standard intended todistinguish impulse noise from other noise, it did so explicitly.We think that there is force in Collier-Keyworth’s argument. Although Table G-16 sets aceiling of 115 dBA on sound pressure levels regardless of the duration of exposure,Wheeling-Pittsburgh Steel Corp., 83 OSAHRC 16\/A2, 11 BNA OSHC 1292, 1294, 1983-84 CCH OSHD(P) 26,482, p. 33,673 (No. 15647, 1983), the special provision for impulse noise warnsagainst impulse noise that exceeds 140 dB. This provision would be superfluous if, as theSecretary argues, the all-inclusive phrase \”sound levels\” in section 1910.95 (a)means that all sound, both impulse and non-impulse, must stay within the limits in TableG-16. Thus, the impulse noise provision suggests that the \”sound levels\”regulated by Table G-16 do not include all sound levels and that impulse noise must beexcluded from calculations under Table G-16.[[6]]It might seem somewhat odd that an answer to this important question might be suggested bya brief second paragraph of a footnote to a table. However, the drafters of the standarddid not intend the impulse noise provision to be relegated to such an obscure position.The provision was originally placed in the next of the standard but later became locatedin the footnote as the result of a printer’s error.[[7]] We therefore ascribe noimportance to the placement of the impulse noise provision.The second provision on which Collier-Keyworth relies is subsection (b)(2), which definesnoise as continuous if the peaks are closer than one second apart. Collier-Keyworthcontends that the Secretary’s classification of closely-spaced impulses as continuousnoise must be viewed as evidence of an intent to distinguish impulse noise from continuousnoise and to exclude impulse noise from the criteria established for continuous noise. TheSecretary’s brief does not address subsection (b)(2) or suggest how it could be reconciledwith his position that impulse noise is subject to the limits of Table G-16.We agree with Collier-Keyworth that subsection (b)(2) appears to represent an attempt todistinguish impulse noise from continuous noise. Both parties agree that continuous noise,i.e., noise of constant intensity, is included in Table G-16 calculations. By definingnoise with peaks closer than one second apart as continuous, subsection (b)(2) obviouslymeans that such noise is to be included in dosage calculations. A provision that sayssomething is included, however, implies that something else is excluded, for there wouldotherwise be no reason for the provision. As the one-second criterion in subsection (b)(2)represents the distinction between impulse noise and non-impulse noise, the sectionsuggests that the drafters of the standard intended to exclude impulse noise from TableG-16.On balance, both the 140 dB peak limit for impulse noise and subsection (b)(2) suggestthat impulse noise is excluded from dosage calculations under Table G-16. Nevertheless,the standard is not entirely clear on its face. It does not expressly exclude impulsenoise from Table G- 16. As the Secretary points out, the standard uses the broad term\”sound levels.\” In light of the ambiguity, we look to evidence extrinsic to thestandard to determine whether the drafters intended to exclude impulse noise from suchcalculations.C. Legislative History of the StandardSection 1910.95 is derived from 41 C.F.R. ? 50-204.10, a standard that was originallypromulgated in 1969 by the Labor Department’s Bureau of Labor Standards to regulate workby government contractors under the Walsh-Healey Government Contracts Act, 41 U.S.C. ?35-45. Section 1910.99 (listing sources of standards); see generally American Can Co., 82OSAHRC 5\/A2, 10 BNA OSHC 1305, 1306-1308, 1982 CCH OSHD (P) 25,899, pp. 32,409-11 (No. 76-5162, 1982)(setting out course of promulgation of standard). Because 41 C.F.R. ?50.204.10 qualified an \”established federal standard\” under section 3(10) of theOccupational Safety and Health Act of 1970 (\”the OSH Act\”), the Secretary ofLabor was authorized to adopt it as an OSHA standard without further rulemakingproceedings. Section 6(a) of the OSH Act, 29 U.S.C. ? 655(a). The Secretary did so on May29, 1971, adopting 41 C.F.R. ? 50-204.10 verbatim as an OSHA standard and codifying it at29 C.F.R.? 1910.95. 36 Fed. Reg. 10466, 10513. Because the Secretary did not, and–withexceptions not pertinent here–could not substantively amend the standard when hesummarily adopted it as an OSHA standard, we must give the standard the same meaning ithad under the Walsh-Healey Act. See American Can, 10 BNA OSHC at 1310-11, 1982 CCH OSHD atpp. 32,413-14; Sherwin-Williams Co., 84 OSAHRC 28\/A2, 11 BNA OSHC 2105, 2109-10, 1984-85CCH OSHD (P) 26,986, pp. 34,701-02 (No. 14131, 1984).The promulgation of 41 C.F.R.? 50-204.10 represented the culmination of a long effort bythe Labor Department and other organizations to develop exposure limits for noise thatwould protect workers against noise-induced hearing loss. Although the preamble thataccompanied the standard when it was adopted under the Walsh-Healey Act sheds no light onthe impulse noise question, the record in this case contains evidence of events leading upto the adoption of the Walsh- Healey standard, as well as evidence of the Secretary’sinterpretation of the standard shortly after its promulgation. The parties presentedwitnesses, James H. Botsford and Herbert H. Jones, who were personally familiar with manyof the events leading up to the standard’s adoption. Their testimony is supplemented bydocumentary exhibits introduced by the parties and other documents that we officiallynotice under section 7(d) of the Administrative Procedure Act, 5 U.S.C. ? 556(e).[[8]]Our examination of the record and the material that we officially notice, together withthe words of the standard, lead us to conclude that the Secretary did not intend for TableG-16 to regulate impulse noise when the standard was promulgated.The documents we officially notice include only Labor Department publications andscientific papers cited in documents that were introduced into evidence. Our purpose intaking official notice is not to determine whether impulse noise is harmful or whether thepreponderance of scientific thinking in 1969 would have favored the regulation of impulsenoise under Table G-16. As we have said, weighing such evidence is not our function butthe Secretary’s. Our purpose is instead to determine the intent of the Secretary in 1969by examining the body of knowledge on impulse noise that influenced the adoption of thestandard. Because our decision rests in part on these officially-noted documents, we shallafford the Secretary an opportunity to rebut them with documents and other evidence of hisintent when he adopted the standard.In 1960, the Walsh-Healey standard for noise stated in its entirety: \”Noise shall bereasonably reduced or eliminated as a means of preventing fatigue or accidents.\” 25Fed. Reg. 13809, 13825 (1960). In early 1964, the department proposed numerical guidelinesthat would establish weekly exposure limits for \”continuous steady noise\” andalso establish a peak limit of 135 dB for \”any exposure….however short in durationother than impact noises. . . . \” U.S Dept. of Labor, Bureau of Labor Standards,\”Suggested Language for a Noise Control Program,\” as printed in \”Noise:Guidelines for control issued by Bureau of Labor Standards,\” Safety Standards 18,20-21, 24 (U.S. Dept. of Labor, March-April 1964 ; see also U.S. Dept. of Labor, Bureau ofLabor Standards, Suggest Language for a Noise Control Program (1965).The Technical Committee on Noise of the American Industrial Hygiene Association(\”AIHA\”) met in May 1964 with Jones (then of the U.S. Department of Health,Education and Welfare) and Botsford (then employed by Bethlehem Steel, its senior noisecontrol engineer). The committee members believed that the newly-published guidelines hadtechnical errors in them and that better guidelines could be developed. The AIHA thereforedecided to offer to the Labor Department the formation of a committee of noise experts torecommend different guidelines. The Labor Department agreed to the formation of such acommittee, which was called the Inter-Society Committee on Guidelines for Noise ExposureControl (\”Inter-Society Committee\”). The committee consisted of two members fromeach of five technical societies: the AIHA, the American Conference of GovernmentalIndustrial Hygienists (\”ACGIH\”), the American Academy of Ophthalmology andOtolaryngology, the American Academy of Occupational Medicine, and the Industrial MedicalAssociation. One of the ACGIH representatives was Dr. Floyd Van Atta of the LaborDepartment, who, according to Jones, \”had primary responsibility in the noise area asfar as the Department of Labor was concerned.\”The Inter-Society Committee issued a report in 1967, which it characterized as the\”first attempt to extract and condense pertinent data from various scientificliterature into a meaningful and authoritative guide.\” Inter-Society Committee,\”Guidelines for Noise Exposure Control,\” 28 Am. Indus. Hygiene J. 418, 419-22(Sept.-Oct. 1967)(I-S). For this inquiry, it is noteworthy that the committee’s guidelineswere directed at developing exposure criteria for only \”steady\” noise. [[9]] Thefollowing are excerpts from the guidelines:I. ForewardNoise-induced hearing loss increases with both the intensity of the noise and the durationof exposure. Generally, many years of exposure to high noise levels are required toproduce significant permanent impairment in the exposed group; however, there will bemarked differences in the hearing of individuals and in their response to noise. . . .These Guidelines will be directed toward the prevention of that portion of the permanenthearing loss resulting from exposure to steady noise.III. Occupational Hearing Loss Control Program A. Evaluation of the Noise Hazard1. Noise Measurement.Continuous or intermittent steady noise is readily measured by standard instruments;impulsive noise requires special procedures not considered here. [Footnote omitted.] 2. Hazard Rating.(a) Continuous Exposure. . . . The first two columns of Table 1. [omitted] indicate thesteady noise levels to which the various groups [of persons with hearing loss] wereexposed . . . .(b) Intermittent and Part-time Exposure. The studies on which Table I and Figure I[omitted] are based, dealt with men exposed to noise during a normal workday, of eighthours’ duration. . .The report went on to explain that, although there were no long-term studies of theeffects of intermittent exposures, the results of some studies implied the \”simplerule\”that for each halving of daily exposure time, the noise levels may be increased by 5 db upto a maximum of 115 dB . . . without increasing the hazard of hearing impairment.The application of this rule is illustrated in the following table: Permissible Increase in dbfor Less than Eight Hours Exposure Daily Exposure Time (Hours) Permissible Increase Above Eight-Hour Criterion (Decibels) 8 0 4 5 2 10 1 15 1 1\/2 20 1\/4 25 Notably, the Inter-Society Committee’s report did not propose any particularpermissible exposure level; for this reason, the AIHA Board found the report unacceptableand suggested that the Inter-Society Committee be disbanded. Shortly thereafter, the ACGIHestablished its own committee to develop a permissible exposure limit for noise as well asother physical agents. Jones was chairman of this committee. The ACGIH Committee drafted aproposed standard that was published for public comment and accompanied by an explanatoryarticle written by Jones, \”ACGIH’s Proposed Threshold Limit Value for Noise,\” 29Am. Indus. Hygiene J. 537-40 (Nov.-Dec. 1968)(ACGIH). See generally Appendix A.1 to thisdecision.The most noteworthy aspect of the ACGIH Committee’s proposal is that it twice stated thatits proposed limits would \”not apply to impulse or impact type of noise.\” ACGIHat 540 (proposed standard). Instead, the proposed standard stated, \”[i]t isrecommended that exposure to this type of noise should not exceed 140 dB peak soundpressure level.\” Id. Jones’ article explained the ACGIH Committee’s reasons fordistinguishing between continuous noise and impulse noise:After considering [various data], the Committee decided that at the present time itappears desirable to establish a limit of 92 dBA for 4 to 8 hours of exposure per day tobroad band continuous noise . . .Laboratory data . . . and . . . field data indicate that, when exposure is for less than afull 8-hour period or is intermittent in nature, the ear can tolerate more acousticalenergy per day than for a single exposure to continuous noise. Considering these twofactors, the limit is increased 5 decibels for each halving of exposure time. The exposuretime is the summation of the exposure periods for the work day regardless of whether thisis a single exposure or an exposure which is intermittent in nature.Very little data is available upon which to base exposure to impact or impulsive noise. Itis known that exposure to a small number of 140 dB impulsive noises of short duration willproduce a temporary threshold shift. Until additional data is available, a limit of 140 dBis being set for impact or impulsive noise.ACGIH at 538 (article)(references omitted).Thus, the criteria proposed by both the Inter-Society Committee and the ACGIH Committeeexcluded impulse noise, with the exception of the ACGIH proposal for a peak limit of 140dB for impulse noise. The reason they otherwise excluded impulse noise was apparentlybecause, as stated in Jones’ article, \”[v]ery little data is available upon which tobase exposure to impact or impulsive noise.\” Both the Inter-Society Committee and theACGIH Committee had cited a number of scientific studies completed by the late 1960’s thatattempted to measure the effect of noise on human hearing. These studies, which areexcerpted in the appendix to this decision, had measured hearing loss caused by variousdegrees of noise exposure. Because most of them involved purely steady-state noise, theyformed a substantial body of evidence from which permissible exposure limits and anexchange rate–the number of decibels by which sound levels could rise if exposure timewas halved–could be derived. However, there was considerably less evidence on which tobase permissible exposure limits to impulse noise. The scientists who attempted to develophearing protection criteria cautioned against applying them to impulse noise, and tendedto regard impulse noise and continuous noise as two distinct problems. The studies citedby the Inter-Society Committee and the ACGIH Committee dealing with \”steady\”noise primarily attempted to determine a safe eight-hour exposure level and an exchangerate that represented an appropriate trade-off of higher intensity for a shorter time.Studies of the harmful effects of impulse noise, by contrast looked for hearing protectioncriteria in terms of factors such as the peak intensity, total number of impulses, andduration of impulses. Thus, the criteria proposed for \”steady\” noise cautionedagainst application to impulse while criteria for impulse noise would not, by their verynature, apply to steady noise. See generally Appendix A.2 – A.7.[[10]]On September 20, 1968, the Labor Department published a proposed standard to regulateworkplace noise exposure. 33 Fed. Reg. 12458, 14259-60. This proposed standard bore verylittle resemblance to the present standard. It basically established a weekly averageexposure limit of 85 dB for \”steady (or equivalent) noise\” and included impulsenoise in its exposure calculations. It spoke of noise with \”intervals . . . more thanone second and . . . maxima less than 1 second each,\” which fits the definition ofimpulse noise. The proposed standard provided that such noise maxima are to be included inthe exposure calculations as if they had durations of 1 second each. See generallyAppendix A.B.The proposal was unfavorably received in the industrial hygiene community. Despite this,on January 17, 1969, a few days before President Johnson’s term expired, the LaborDepartment issued a package of Walsh-Healey standards, including a noise standard verysimilar to that which had been proposed. 34 Fed. Reg. 788, 790-91. The promulgatedstandard retained the exposure limit of the proposed standard and the provision that dealtwith impulse noise.Before the promulgated standard became effective, it was stayed by the new Secretary ofLabor. 34 Fed. Reg. 2207 (1969). On May 20, 1969, the Labor Department issued a new noisestandard that differed radically from the earlier one. 34 Fed. Reg. 7946, 7948-49. Exceptfor some subsequent corrections (35 Fed. Reg. 1015 (1970)) , the new standard is identicalto the one at issue in this case . Major differences between the earlier standard and thelater standard include provisions relevant to the impulse noise issue. The earlierstandard explicitly stated that noise with maxima less than one second in duration andgreater than one second apart, i.e., impulse noise, was to be included in weekly exposurecalculations. However, the final standard contained no similar provision and included aprovision with no counterpart in the earlier standard– a recommended limit of 140 dB forimpulse noise.The final standard strongly resembled that adopted by the ACGIH on May 12, 1969, eightdays before the final version of the Walsh-Healey standard was adopted.[[11]] Jones wasstill the chairman of the ACGIH Committee; he stated that Dr. Van Atta of the LaborDepartment had been aware of the workings of the Committee and of its proposed standard,and that he had received advance copies of the final ACGIH standard. Relevant excerptsfrom the ACGIH standard follow:Threshold Limit Values NoiseContinuous or intermittentThe sound level shall be determined by a sound level meter . . . operating on theA-weighting network with slow meter response. Exposure shall not exceed that shown inTable 1Table 1Permissible Exposures Duration per Day Hours Sound level dB(A) 8 90 6 6 92 t 4 95 3 97 2 100 1 1\/2 102 1 105 3\/4 107 1\/2 110 1\/4 115-C** 11ACGIH, \”Threshold Limit Values of Physical Agents\” (1969), reprinted inFundamentals of Industrial Hygiene, Appendix A*Sound level in decibels as measured on a standard level meter operating on theA-weighting network with slow meter response. **Ceiling Value___________________________These values apply to total time of exposure per working day regardless of whether this isone continuous exposure or a number of short-term exposures but do not apply to impact orimpulse type of noises.When the daily noise exposure is composed of two or more periods of noise exposure ofdifferent levels, their combined effect should be considered, rather than the individualeffect of each. If the sum of the following fractions: C1\/T1\u00a0 + C2\/T2\u00a0 + ……. Cn\/Tnexceeds unity, then, the mixed exposure should be considered to exceed the threshold limitvalue, C1 indicates the total time of exposure at a specified noise level, and T1indicates the total time of exposure permitted at that level . . .Impulsive or impact noiseIt is recommended that exposure to impulsive or impact noise should not exceed 140decibels peak sound pressure level-CThis ACGIH standard is very similar to the Walsh-Healey standard ultimately promulgated bythe Secretary of Labor. Indeed, the final Walsh-Healey standard was much closer to theACGIH standard than it was to the earlier Walsh-Healey standard that is supplanted. Inparticular, the most important part of the final Walsh-Healey standard, the table listingthe permissible exposure limits, almost identical to the corresponding table in the ACGIHstandard. The passages on impulse noise and the cumulation formula are also nearlyidentical to those in the ACGIH standard. In light of the similarities between the twofinal standards, and of Jones’ testimony that Dr. Van Atta of the Labor Department wasfamiliar with the proceedings of the ACGIH Committee and had advance copies of its workproducts, we infer–as do both the Secretary and Collier-Keyworth–that the final ACGIHstandard heavily influenced the final Walsh-Healey standard.[[12]]The Walsh-Healey standard does not state explicitly that impulse noise is excluded, asdoes the ACGIH standard, and the absence of such a statement in the Walsh-Healey standardmight be taken to mean that the Secretary rejected this aspect of the ACGIH standard,deciding to include impulse noise in Table G-16 calculations. However, the finalWalsh-Healey standard also does not state explicitly that impulse noise is included insuch calculations. In this critical respect, it departed from the earlier Walsh- Healeystandard, which expressly included impulse noise. Moreover, the final Walsh-Healeystandard contained the impulse noise provision and subsection (b)(2), both of whichsuggest that impulse noise was to be excluded from Table G-10.Although we cannot determine solely from the standard’s legislative history to this pointwhether the Secretary intended impulse noise to be included in Table G-16 calculations, itdoes reveal several highly significant facts: Many of the scientists and organizationswhose attempts to develop criteria for noise were cited by the ACGIH Committee and theInter-Society Committee did not believe it either necessary or appropriate for thecriteria they developed for steady or continuous noise to apply to impulse noise. Indeed,it appears that the preponderant thinking in the scientific community that was cited bythe ACGIH Committee and the Inter-Society Committee was to exclude impulse noise fromcriteria for steady noise. The Labor Department was evidently aware of this, for itstechnical expert on noise served on the Inter-Society Committee and was aware of the viewsof and the limits developed by the ACGIH Committee. The standard it adopted drew heavilyon the work of the ACGIH Committee and, indirectly, that of the Inter-Society Committee.There is also strong evidence that the Department of Labor agreed with the body ofscientific opinion cited by the ACGIH Committee and the Inter-Society Committee.On December 4, 1970, after the noise standard was adopted under the Walsh-Healey Act, theLabor Department’s Bureau of Labor Standards published Bulletin 334 , Guidelines to the Department of Labor’s Occupational Noise Standards for FederalSupply Contracts (Dec. 4, 1970), a detailed manual explaining to government contractorswhat their duties were. The 1970 version [[13]] of Bulletin 334 states in part:Table 1 [equivalent to Table G-16] indicates [excessive noise] ……. Employees must notbe exposed to steady sound levels above 115 dBA, regardless of the duration………The \”slow\” response [on the sound level meter] is another setting…….. . which causes it to average out high level noise of brief duration (such ashammering), rather than responding to the individual impact noises. Impulse or Impact NoiseThe last sentence in paragraph (d) of section 50-204.10 states:\”Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressurelevel.\”This sets the upper limit of sound level to which a person should be exposed, regardlessof the brevity of the exposure.In contrast with the 115 dBA upper limit for steady noise, the higher intensity for impactnoise is permissible because the noise impulse resulting from impacts, like hammer blowsor explosive processes, is past before the ear has time to react fully. Impact noiselevels are to be measured only with an impact meter or an oscilloscope.Variable NoisesParagraph (c) of section 50-204.10 states the final consideration in determining whetheror not a permissible sound level is being exceeded:\”(c) If the variations in noise level involve maxima at intervals of 1 second orless, it is to be considered continuous.\”This means that where the sound level meter on the A scale at slow response moves up froma generally steady reading, say from 88 to 92 dB, at intervals of one second or less, thehigh reading shall be taken as that to be used in Table 1 [equivalent to Table G-16].As a corollary to this, intermittent sounds of brief duration at intervals greater thanone second should, as far as practical, be measured as to intensity and duration and thetotal duration over a day be ascertained. This total should be entered in the equationgiven in footnote 1, Table 1, to determine the permissible limit. These intermittentsounds, which can be measured with a sound level meter, should not be confused withimpulse sounds of very short duration resulting from impacts or explosions.Id. at 2, 6-7 (emphasis added).Bulletin 334 went on to state that noise levels were to be measured with a sound levelmeter, set for A scale and slow response, meeting the specifications for sound levelmeters established by the American National Standards Institute (ANSI) in ANSI S1.4-1961,\”Specification for General- Purpose Sound Level Meters.\” Bulletin 334 at 14.This ANSI standard contains the following provisions:IntroductionIt should also be recognized that the ballistics and other characteristics of theindicating instrument are adapted mainly for measuring ordinary machinery noises and othersounds of a reasonably constant character. For intermittent sounds, and more particularlyfor repetitious sounds involving high peak-to-average ratios in sound pressure, and forimpact noises, other specialized equipment will be required in place of the ordinaryindicating instrument.ANSI S1.4-1961 at p. 6 (emphasis added).Several significant points emerge from Bulletin 334. The explanation of why a higher peaklevel. is permitted for impulse noise than for steady noise-that the ear does not reactfully to impulse noise–supplies a reason why impulse noise would be excluded from TableG-16. The statement indicates that the Secretary was aware of the scientific reasons whythe investigators who had developed criteria by 1969 for steady noise did not apply theircriteria to impulse noise. The instruction in Bulletin 334 about including\”intermittent sounds of brief duration\” in dosage calculations, coupled with thecaveat against confusing such sounds with impulse noise, is tantamount to an explicitstatement that impulse noise is to be excluded from such calculations. Finally, theprovision in ANSI S1.4-1961 that standard sound level meters cannot be used to measureimpulse noise, together with the statement in Bulletin 334 that sound level meters usedfor noise surveys must conform to ANSI S1.4-1961, is a further indication that impulsenoise is excluded from the standard except for the 140 dB peak level provision.[[14]]C. OSHA’s Enforcement and Later InterpretationsThe record also shows that it was OSHA’s practice to exclude impulse noise from Table G-16calculations when enforcing the standard. Anne Hart, the OSHA industrial hygienist who inspected Collier-Keyworth’s plant, answered \”no\” whenasked, \”[y]ou are not supposed to include impulse noise in your dosimeter or soundlevel meter measurements, are you?\” Thomas Rockwell, an expert in noise measurementand control and a consultant to numerous corporations, testified that he wrote a letter tothe Cleveland Area Office of OSHA asking if he was correct in understanding that thestandard excluded impulse noise, and received in response a phone call from Fred Boelter,an industrial hygienist in the Chicago office, confirming that understanding. We also notethat Dr. John Barry, a noise expert employed by OSHA since 1976, wrote in a paperpresented at Purdue University in 1979: \”This standard [29 C. F. R. ? 1910.95(a)-(b)] sets the permissible exposure level for non-impulse noise at 90 dBA for an8-hour-per-day duration and less than or equal to 140 dB peak sound pressure level forimpulse noise irrespective of its duration.\”[[15]]Dr. Barry also was the principal author of a document instructing OSHA industrialhygienists in the proper techniques for determining compliance with the standard. Thisdocument was first published on April 2, 1979, as OSHA Instruction CPL 2-2.20 and waslater incorporated in OSHA’s Industrial Hygiene Field Operations Manual(\”IHFOM\”) as Chapter IV.[[16]] Section C.1.e provided:Where both continuous and impulse noise are present, measure the background on the dBAfast mode to determine if the continuous noise is above the levels found in Table G- 16,29 C. F. R. ?1910.95.Thus, OSHA instructed its inspectors to determine whether the continuous component alonein a mixture of continuous and impulse noise exceeded the limits of Table G-16. Hart’sacknowledgment that she was not supposed to include impulse noise in dosage measurementstherefore reflected an official, agency-wide practice [[17]]Our understanding of OSHA’s early enforcement practices is further aided by OSHA’scomprehensive proposal in 1974 to completely replace section 1910.95 with a more precisestandard. The standard that OSHA then proposed and the explanation accompanying itindicate that OSHA did not view the existing standard as including impulse noise in dosagecalculations. The proposed standard would have retained the 90 dBA limit in the existingstandard but would have coupled that limit with requirements for a stringent hearingconservation program when the eight-hour time weighted average noise level exceeded 85dBA. 39 Fed. Reg. 37773, 37774 (Oct. 24, 1974). Although OSHA proposed to retain the 90dBA limit at which engineering controls, administrative controls, and personal protectiveequipment were required, it proposed to draw a sharp distinction between steady-statenoise and impulse noise, explicitly excluding the latter from dosage calculations. Theproposed standard provided in part:? 1910.95 Occupational noise exposure.(c) Permissible exposure limits.(1) Steady state noise—single level. (i) The permissible exposure to continuous noiseshall not exceed an eight-hour time-weighted average of 90 dBA with a doubling rate of 5dBA. For discrete permissible …… limits, refer to Table G-16a [omitted, similar toTable G-16].(ii) Where Table G-16a does not reflect actual exposure times and levels, the permissibleexposure to continuous noise at a single level shall not exceed [an amount determined by agiven formula] where \”L\” is the workplace sound level measured in dBA on theslow scale of a standard sound level meter….(2) Steady state noise–two or more levels. Exposures to continuous noise at two or morelevels may not exceed [a dose computed by the cumulation formula] where C is the actualduration of …… a given steady state noise level …… (3) Maximum steady state noise level. Exposure to continuous noise shall not exceed 115dBA ……(4) impulse or impact noise. (i) Exposures to impulse or impact noise shall not exceed apeak sound pressure level of 140 dB.(ii) Exposure to impulses of 140 dB shall not exceed 100 such impulses per day. …….For each decrease of 10 dB in the peak sound pressure level of the impulse, the number ofimpulses to which employees are exposed may be increased by a factor of 10.39 Fed. Reg. at 37775. The preamble to the proposed standard explained why OSHA proposedto treat impulse noise in this way:The present OSHA standard recommends that impact or impulse sounds not exceed a peak soundpressure level of 140 dB. The Advisory Committee suggested that this limit be mademandatory. OSHA. has made an addition to the Advisory Committee’s recommendation withrespect to impulse noise exposure, because the actual exposure is a summation of the peaksound levels of the impulses and the number of impulses. OSHA proposes to limit exposureto impulses at 140 dB to 100 per day and to permit a tenfold increase in the number ofimpulses for each 10 dB decrease in the peak pressure of the impulse. For example, thenumber of impulses allowed at 130 dB would be 1,000 per day and the number of impulsesallowed at 120 dB would be 10,000 per day.39 Fed. Reg. at 37774. Although the proposed standard thus specified separate exposurelimits for steady-state noise and impulse noise, its preamble gave no indication that OSHAconsidered the proposed standard a departure from the existing standard. Indeed, itsexplanation of the proposed standard indicates that OSHA viewed the 140 dB peak limit asbeing the only provision in the existing standard addressed to impulse noise. While thisfalls somewhat short of being a formal interpretation of the existing standard, itsupplements the other evidence tending to show that OSHA had interpreted the existingstandard to exclude impulse noise from Table G- 16.The Secretary asserts that it was not his customary practice to exclude impulse noise fromTable G-16. He cites Turner Co., 76 OSAHRC 108\/A2, 4 BNA OSHC 1554, 1976-77 CCH OSHD (P)21,023 (No. 3635, 1976). rev’d on other grounds, 561 F.2d 82 (7th Cir. 1977), as anexample of a case where a citation based on impulse noise from power presses was issuedand affirmed. Turner does not support the Secretary’s argument. The impulse noise issuewas not raised in Turner and the parties stipulated that the noise levels exceeded thosepermitted by Table G-16. 4 BNA OSHC at 1556, 1976-77 CCH OSHD at p. 25,274. Moreover,power press noise is not inevitably impulse noise. If the noise maxima occur morefrequently than once per second, a situation that may well have been the case inTurner,[[18]] the noise is defined as continuous by subsection (b)(2) of the standard. Inany event, even if Turner did involve impulse noise, a single citation does not show anenforcement policy and does not rebut the otherwise overwhelming evidence that OSHAinterpreted the standard to exclude impulse noise from Table G-16.Bulletin 334 is nearly contemporaneous with the adoption of the standard, consistent withOSHA’s early enforcement policy, and therefore likely to reflect the understanding ofthose in OSHA who drafted the standard. We cannot, however, say the same of the argumentsin the Secretary’s brief. The Commission has generally not considered interpretations ofstandards in the Secretary’s briefs to be authoritative. E.g., C. F. & I. Steel Corp.,86 OSAHRC _____, 12 BNA OSHC 2067, 2074, 1986 CCH OSHD (P) 27,691, pp. 36,139-40 (No.79-4786, 1986). It has long been the experience of the Commission that interpretationsadvanced before the Commission in the Secretary’s briefs often are interpretations made tosupport litigation positions. They are not necessarily interpretations traceable to theintent of the standard’s drafters. Id.; see Investment Company Institute v. Camp, 401 U.S.617, 626-28 (1971)(counsel’s efforts in litigation are \”hardly tantamount to anadministrative interpretation\” of a statute). This is a vital distinction, for it isthe drafters of a standard who incorporate into it the policies and compromises that therulemaking record demonstrates are appropriate. To give weight to an administrativeinterpretation not traceable to the standard’s drafters would effectively permit theSecretary to amend the standard without the safeguards mandated by Congress to affordpersons affected by the standard an opportunity to participate in the rulemaking process.The brief the Secretary filed in this case gives us no reason to believe that theinterpretation it advances is traceable to the intent of the drafters. The brief does notaddress subsection (b)(2) of the standard and its use of the word \”continuous.\”It does not mention Bulletin 334, or the 1974 proposed standard and its preamble. It doesnot purport to have been written or reviewed by lawyers who consulted with the drafters ofthe standard or who participated in the drafting of the standard. The brief does addressthe 140 dB impulse noise provision but misapprehends the events that lay behind itsadoption. See note 12 above. It also relies on the testimony adduced in this litigation onthe harmfulness of impulse noise and alludes to the findings OSHA made in 1981 to supportthe hearing conservation amendment, though neither is evidence of what the Secretaryintended when he adopted section 1910.95(a)-(b). In sum, the Secretary’s brief reflectsOSHA’s current appreciation of impulse noise but provides no insight into what theSecretary of Labor intended in 1969. It is therefore entitled to no weight here.Bulletin 334 and the Secretary’s early enforcement policy are entitled to considerableweight, however. Bulletin 334 is \”a nearly contemporaneous interpretation of thestandard by its drafter.\” Wheeling-Pittsburgh Steel, 11 BNA OSHC at 1294, 1983-84 CCHOSHD at p. 33,673. Its view that impulse noise is to be excluded from Table G-16calculations is also reflected in OSHA’s original enforcement policy and the understandingof OSHA officials in the 1970’s, such as Dr. Barry, who were responsible for thestandard’s enforcement. And it is consistent with the rationale behind the 1974 proposedstandard, a document that explicitly established separate limits for impulse noise andsteady-state noise and gave no hint that OSHA viewed this as a departure from the currentstandard.The Secretary argues that exclusion of impulse noise \”is fundamentally inconsistentwith [the standard’s] goal of safeguarding human hearing.\” That a standard addressesa problem does not mean that it was intended to safeguard employees from it entirely.Drafters may lack enough information to justify a comprehensive treatment or to know evenhow to write a comprehensive standard. They may therefore decide to regulate a step at atime, going as far as their knowledge carries them and leaving the rest for another day.That happened here. From its text and legislative history, from Bulletin 334 and OSHA’searly enforcement policy, we find that the drafters of section 1910.95(a)-(b) intended toexclude from Table G-16 impulse noise–that is, noise with sharp energy peaks lasting lessthan one second and spaced more than one second apart. We therefore vacate citation items1a(B) and (D), and 1b(B) and (D), which are based on exposure readings of employeesexposed to impulse noise.III. Noise Exposure of EmployeesThe Secretary alleges that Collier-Keyworth employees were exposed to noise in excess ofthe standard’s limits and that the company did not take the precautions required by thestandard to protect the employees. The record shows that the noise to whichCollier-Keyworth’s employees were exposed consisted of a mixture of noise from themachines on which they were working and background noise that was present even when theirmachines were not operating. The background noise was purely continuous noise, i.e., noiseof unvarying or slowly varying intensity. The machine noise basically falls into twocategories:(1) purely impulse noise, i.e., noise with sharp energy peaks spaced atintervals greater than one second; and (2) noise resulting from impulses spaced less thanone second apart, which is defined as continuous by the standard and which, for the sakeof convenience, we shall call \”quasi-continuous\” noise. To prove over-exposure,the Secretary introduced into evidence dosimeter readings that measure an accumulateddosage from all noise present in the work environment, including impulse noise. We haveconcluded, however, that pure impulse noise must be excluded from measurements todetermine compliance with Table G-16. Thus, in evaluating the dosimeter readingsintroduced by the Secretary, we must determine whether they were contaminated bysufficient impulse noise to render them unreliable measures of compliance with Table G-16levels. We find, for the reasons discussed in below, that some samples were socontaminated but that others were not, for they registered quasi-continuous noise.Collier-Keyworth also argues, however, that dosimeters do not reliably measurequasi-continuous noise.A. The Use of Dosimeters to Measure Quasi-Continuous NoiseCollier-Keyworth argues, and Judge Furcolo agreed, that in impulsive noise environments,the dosimeters used by OSHA may not be relied on to prove violations of Table G-16exposure limits because they indicate noise levels significantly higher than the\”true noise levels.\” In making this argument, the company does not distinguishbetween pure impulse noise and quasi-continuous noise.Such a distinction must be made, however, Although pure impulse noise must be excluded indetermining compliance with table G-16, quasi-continuous noise is included. Dosimeterreadings in environments containing significant amounts of pure impulse noise areinherently unreliable regardless of the accuracy with which they measure impulse noise,for they should not be measuring such noise at all. They should, however, be measuringquasi-continuous noise, and the accuracy with which they measure this type of noise iscritical. Thus, we must consider Collier- Keyworth’s argument to the extent it questionsthe accuracy with which OSHA’s dosimeters measure quasi-continuous noise.We will assume in this discussion that ColIier-Keyworth is correct in its assertion thatdosimeters in impulsive noise environments register dosages as if noise level’s weresignificantly higher than the \”true noise levels.\”[[19]] However,Collier-Keyworth’s argument cannot logically be seen as merely an objection to dosimetersbut to the standard’s prescription of the slow response mode of measurement. As we havesaid, a noise dosimeter is in effect a sound level meter with additional circuitry thatautomatically records dosages in the manner set out in the cumulation formula of TableG-16. And, as we shall discuss below, the circuitry of a dosimeter that arguably causes itto overcount \”true noise\” levels is not its additional dosage- calculatingcircuitry but the slow response circuitry it shares with conventional sound level meters.Thus, despite the emphasis in Collier-Keyworth’s brief on the inability of dosimeters toreliably detect \”true noise levels,\” its argument could apply with equal forceto conventional sound level meters. Indeed, Collier-Keyworth’s acoustical engineeringexpert. Thomas Rockwell, admitted that he would obtain the same results using a slowresponse sound level meter as a slow response dosimeter.Dosimeters and sound level meters employing slow response seem to overcount the \”truenoise level\” because slow response instruments have an integration time of onesecond, that is, they register an impulse as if it were spread out over a second. A burstof sound lasting one-half second would therefore be displayed as if it were one secondlong. Because the slow response integration time is longer than the duration of such anoise impulse, the slow response mode distorts the \”true\” noise pattern, makingimpulses appear longer in duration but lower in peak intensity.[[20]]Collier-Keyworth argues that the net effect of the slow response mode is to causedosimeters to read higher than the \”true noise level.\” The problem withCoIlier-Keyworth’s argument is that section 1910.95(a)-(b) does not regulate \”truenoise levels.\” The standard regulates sound levels (1) as measured by a standardsound level meter, (2) as detected by slow response, (3) as weighted by frequencyaccording to the A-weighting network (which weights each sound frequency according to theear’s response to it), (4) excluding impulses more than a second apart, and (5) treatingimpulses less than a second apart as continuous. Indeed, it is rather pointless to speakof \”true noise levels\” because they can never be measured. To measure \”truenoise levels\” would require an ideal instrument having, among other things, aninstantaneous response time, that is, an integration time of zero. One could build a soundlevel detector with a short response time, perhaps an eighth of a second, as fast responseinstruments have. But such an instrument would still not be measuring \”true noiselevels.\”Inasmuch as section 1910.95(a)-(b) does not regulate \”true noise levels\” butlevels as detected by slow response instruments, Collier-Keyworth’s argument is really acomplaint about the standard’s prescription of slow response. Collier-Keyworth seems todesire that sound level meters and dosimeters be employed at fast response so as to moreclosely approximate the \”true level\” of impulse noise.[[21]] However, thestandard specifies the use of slow response and whatever deviations from true noise levelsthat mode introduces were within the contemplation of its drafters. That slow responseinstruments give greater weight to impulse noise than fast response instruments must beregarded as one of the many compromises that the Secretary struck when he adopted thestandard. Just as the Secretary could provide that impulses recurring at greater thanone-second intervals not be counted at all, he could provide for a measurement techniquethat gives additional weight to impulses closer than one second together. \u00a0Collier-Keyworth does not point to any illegality in the Secretary’s choice of slowresponse.[[22]] We therefore reject Collier-Keyworth’s arguments that slow responsedosimeters may not be used to detect exposures greater than those permitted by Table G-16.[[23]]B. Evidence of ExposureWe now consider whether OSHA proved that any Collier-Keyworth employee was over-exposed toquasi-continuous noise. On April 14, 1980, OSHA industrial hygienist Anne Hart began aninspection of Collier-Keyworth’s plant aimed at determining whether the company was incompliance with the noise standard. Hart attached General Radio Model 1954 dosimeters tofive Collier-Keyworth employees, who wore the dosimeters throughout their work day. One ofthe dosimeters malfunctioned, and Hart returned on April 18 to obtain a dosimeter readingfor that employee. Hart also measured the noise levels in the employees’ hearing zones atvarious times throughout the inspection by using a sound level meter. The employees whowere sampled operated power presses and lathes in four different areas of the plant.Presses 2208, 2209, and 2210 (citation items 1a(A)) and 1b(A)) are 60-ton Bliss open-backinclinable power presses used by Collier-Keyworth to fabricate metal parts. The pressesoperate automatically. Sheet steel is fed into the press bed by a feeder mechanism. A dieattached to a ram above the bed descends and stamps the part out of the stock. The part isremoved from the bed by high-speed air blown out of nozzles. The three presses werelocated within ten feet of each other.The presses were operated by Paul LeBlanc and Norman Melanson. The operators’ dutiesincluding changing dies, making necessary adjustments, installing coils of sheet steelstock, threading the stock into the die area, and monitoring the operation of the presses.An operator had to be in the general area of the machines while they were operating, butthe operation of each machine did not have to be monitored closely.Using a sound level meter, Hart measured noise levels in the vicinity of the pressesranging from 85 to 104 dBA, with readings below 90 dBA occurring only when none of thepresses were operating. The dosimeter worn by LeBlanc read 305% it the end of the day, andthat worn by Melanson read 286%. These readings indicate that both employees were exposedto approximately three times the permissible dose, or, viewed a different way, that theywere exposed to time-weighted average sound levels of about 97.6 dBA and 98.0 dBA. See 29C.F.R. ? 1910.95, Appendix A, Table A-1 (hearing conservation standard). Hart testifiedthat she timed the presses using a watch with a second hand and found that the impacts foreach machine were less than one second apart. She also stated that the strokes of thethree machines were not synchronized, so that when all three presses were running, thenoise peaks were less than one-third second apart.Collier-Keyworth’s chief engineer, Robert Cochran, testified that the presses had amaximum stroke rate of 80 per minute. The actual stroke rate was controlled automaticallyby the feeder mechanism and was different for each part being produced. Each machine wasused to produce about 30 different parts. Cochran did not know the stroke rates thatcorresponded to the various parts.Following the inspection, noise measurements were made in Collier-Keyworth’s plant byexperts for both parties: Thomas Rockwell for Collier-Keyworth and John Barry for theSecretary. Both experts fed the output from sound level meters into strip-chart recorders,which draw tracings showing how the noise level’s fluctuate with time. Tracings made byRockwell on June 17, 1980, show press 2208 operating at 57.5 strokes per minute, press2209 at 48 strokes per minute, and press 2210 at 56 strokes per minute. Rockwell testifiedthat Cochran told him that the presses were producing some of the same parts they had beenmaking on the day of Hart’s inspection.Under subsection (b)(2) of the standard, noise that consists of a series of impulses lessthan one second apart is treated as continuous. This quasi continuous noise will beproduced by a press operating at a stroke rate of more than one per second, or sixty perminute. A press stroking slower than once per second will, however, generate impulsenoise. Collier-Keyworth’s presses can stroke as fast as eighty per minute, but the actualrate depends on the part being produced and for some parts is slower than sixty perminute. Collier-Keywortn’s presses therefore generate quasi-continuous noise at certaintimes and impulse noise at other timesThe evidence shows that LeBlanc and Melanson were exposed only to quasi-continuous noiseon the day of the inspection. Hart testified that she timed the presses and that the timebetween strokes was less than one second for each press. There is no evidence directlycontradicting Hart’s testimony.[[24]] Collier-Keyworth production records showing theparts produced on the day of the inspection were introduced into evidence, but the companypresented no evidence on the stroke rates that corresponded to those parts.Collier-Keyworth did show that on a later date, when Rockwell measured the noise from itspresses, the presses were stroking slower than once per second, indicating that the noiseat that time was impulse noise. Moreover, Rockwell testified that Cochran had told himthat the presses were producing some of the same parts when he was in the plant as whenHart made her inspection. However, Rockwell spent parts of three days in the plant, andthe production records introduced into evidence show that the presses typically produceddifferent parts on different days. Therefore, during the three days Rockwell was in theplant, the presses probably produced several different parts each, including some thatwere made during Hart’s inspection and others that were not. In the absence of evidencethat the parts produced when Rockwell made the strip chart recordings showing the pressesoperating slower than once per second were the same as those manufactured during Hart’sinspection, Rockwell’s testimony does not contradict Hart’s evidence that the presses werestroking faster than once per second.We also note that it is not the noise generated by a machine, but the noise heard by anemployee, that the standard regulates. During most LeBlanc’s and Melanson’s workday, twoor three presses were operating and generating noise. As the presses were notsynchronized, the noise maxima that they heard would have occurred about twice per secondwith two presses running and about three times per second with three presses operating. Inany event, because each press individually produced quasi-continuous noise, two or threepresses operating at individually produced quasi- continuous noise, two or three pressesoperating at the same time would also produce quasi- continuous noise.Because LeBlanc and Melanson were exposed only to quasi-continuous noise, their dosimeterreadings did not include any measurements of impulse noise. Those dosimeter readings–305%for LeBlanc and 286% for Melanson–facility indicate exposure that exceeds permissiblelimits. Collier- Keyworth asserts that a number of factors can affect dosimeter readings,including electromagnetic fields or radio waves, wind, orientation of the microphone,chemicals, temperature effects, moisture, and noise made by the employee wearing thedosimeter. There is no evidence, however, that any of these factors significantlydistorted the dosimeter readings made during the OSHA inspection of Collier-Keyworth’splant. The dosimeter readings obtained by industrial hygienist Hart are consistent withsound level meter readings she made on the day of the inspection as well as withmeasurements made on later days by Rockwell and Barry. Hart measured the noise level inLeBlanc’s hearing zone to be 99-102 dBA when LeBlanc was standing by press 2208 withpresses 2208 and 2209, but not 2210, operating. When Melanson was standing beside press2209 with 2208 and 2209 running, the noise level was 100-104 dBA.[[25]] At certain times,Hart measured noise levels below 90 dBA for both LeBlanc and Melanson with none of thepresses running. Hart noted, however, that all three presses were usually running duringher inspection. Also, chief engineer Cochran testified that Collier-Keyworth had no excesspress capacity, indicating that the presses operated full-time except when dies werechanged or adjustments made.As noted above, the dosimeter readings Hart obtained for both LeBlanc and Melanson wereapproximately 300% of the permitted daily dose. An employee exposed to a constant noiselevel of 100 dbA for 6 hours would receive a dosage of 300%. The sound level meterreadings made by Hart show that LeBlanc and Melanson were sometimes exposed to noiselevels less than 90 dBA, out were exposed to noise levels around 100 dBA for most of their8-hour shifts. Thus, the sound level meter readings tend to show that the dosimeters wereaccurately measuring and recording the noise levels to which LeBlanc and Melanson wereexposed.In summary, we conclude that on April 14, 1980, LeBlanc and Melanson, the operators ofpresses 2208, 2209, & 2210, were exposed to noise in excess of the limits permitted byTable G- 16.Press 2216 (items 1a(C) and 1b(C)) is a 60-ton Bliss press similar to the three pressesdiscussed in the previous section but located some distance from them. In April 18, 1980,industrial hygienist Hart attached a dosimeter to press operator Alan Sund. After 202minutes, or about 3.3 hours, the dosimeter read 167%. Sound level meter readings made byHart in Sund’s hearing zone at four different times over the period the dosimeter wasoperating were 103-107 dBA while the press was running. Sund was then observing themachine from a distance of one to two feet. As with the other presses, Hart testified thatshe timed the stroke rate and that the time between strokes was less than one second. OnJune 17, 1980, Rockwell measured the stroke rate of the press to be 45 strokes per minute,but there is no evidence that the press was producing the same part, and thereby runningat the same speed, as during Hart’s inspection.For much the same reasons as previously discussed, we find that the evidence shows Sundwas exposed to noise exceeding the standard’s permitted limits. Hart’s testimony that thetime between strokes was less than one second on the day the inspection establishes thatthe noise was continuous within the meaning of the standard. The dosimeter readingfacially indicates that Sund was exposed to excessive noise. The sound level meterreadings indicated that Sund was exposed to 103-107 dBA for about 3.3 hours. At 103 dBA,the lowest sound level or this range, only about 1.3 hours of exposure is permitted. Thus,the sound level meter readings corroborate the measurement of excessive exposure made bythe dosimeter.Press 352 (items 1a(D) and 1b(D)) is a manually-fed machine used for small bending jobs.On April 14, 1980, Hart obtained a reading of 256% from a dosimeter attached to pressoperator Ernest Couture. According to Hart, the press strokes once every two or threeseconds. With the machine not operating, Hart measured the noise in Couture’s hearing zoneto be from 84 to 88 dBA. With the machine operating, she measured noise levels as high as95 dBA.We conclude that the Secretary did not prove Couture was exposed to excessive noise.Because the press stroked only once every two to three seconds, the noise that resultedfrom the press’s operation was impulse noise, which is not regulated by Table G-16. Theonly continuous noise to which Couture was exposed was background noise measured to be 84to 88 dBA, levels within the standard’s limits for any exposure time. We therefore findthat Couture was not exposed to noise exceeding the standard’s limits and we will vacateItems 1a(D) and 1(b)(D)).Lathes 6040 and 3018 (items 1a(B) and 1b(B)) are used to cut metal tubing and chamfer theends. Both lathes were operated by a single employee, Ken Thompson. Lathe 6040 wasoperated manually, while lathe 3018 was automatic. Therefore, when both lathes wereoperating, Thompson would be standing beside lathe 6040. On April 14, 1980, a dosimeterattached to Thompson during his shift yielded a reading of 158.5%. According to soundlevel meter readings made by industrial hygienist Hart, the noise level in Thompson’shearing zone ranged from 85 to 107 dBA.Lathe 6040 was relatively quiet and, when operated alone, produced noise levels below 90dBA. Thus, the noise that caused the standard’s limits to be exceeded was generated bylathe 3018. That lathe sometimes emitted a very loud high-pitched squeal, but at othertimes the squeal was missing. Hart recorded noise levels of 107 dBA when the squeal wasevident, but only 92 dBA with both lathes running but no high-pitched squeal present. WhenDr. Barry later visited Collier- Keyworth’s plant, he measured 118 dBA in the hearing zoneof the operator of lathe 3018. Upon analyzing the frequencies contained in the noise,Barry found that the excessive noise primarily occurred at 8000 hertz and higher,frequencies which the human ear would perceive as very high.Both Barry and Rockwell made strip chart recordings of the lathe noise. These recordingsshow very pronounced short bursts of noise, much like the strip chart recordings for thepower presses. The charts are not labeled with time scales that would enable the timebetween bursts to be measured, but Rockwell testified that the charts show a peak-to-peakseparation greater than one second, indicating that at least some of the noise is impulsenoise.We conclude that the Secretary failed to prove Thompson was exposed to excessive noise.Some of the noise to which Thompson was exposed, and which was detected by the dosimeter,was impulse noise that must be excluded under the standard. There is no basis to concludethat Thompson’s dosimeter reading would have shown overexposure if the impulse noise hadbeen excluded. Indeed, it is doubtful that the Secretary proved overexposure even assumingthat impulse noise were to be included. Industrial hygienist Hart testified that Type 2sound level meters and dosimeters, the type she used in her inspection, generally have aninherent error factor of two dBA; when that error is cumulated over time, it creates apotential error of 32% in the dosimeter reading.[[26]] Thus, a dosimeter reading of158.5%, as was obtained for Thompson, would generally be outside the instrument’s range oferror and would show overexposure. However, the record shows that the noise to whichThompson was exposed was of very high frequency, predominantly 8000 hertz. At 8000 hertz,type 2 sound level meters and dosimeters have an inherent error factor of 6.5 dBA.[[27]]This means that a dosimeter containing a Type 2 sound level meter would have to read over240% to show overexposure once the inherent error of the instrument at 8,000 hertz istaken into account. Cf. 29 C.F.R. ? 1910.95, Appendix A, Table A-1 (hearing conservationstandard) (entry for 96.3 dBA corresponds to dose of 240 percent). Thus, where the noiseis predominantly at 8,000 hertz, a dosimeter reading of 158.5%, the reading obtained forThompson, does not show overexposure within the accuracy limit of the instrument.We therefore vacate citation items 1a(B) and (D), and 1b(B) and (D). Having found thatOSHA proved over-exposure to quasi-continuous noise by press operators LeBlanc, Melansonand Sund–the employees involved in items 1a(A) and (C), and 1b(A) and (B)–we must nowdetermine whether the Secretary showed that Collier-Keyworth violated the standard byfailing to take required precautions against excessive noise exposure.IV. Precautions Against Noise ExposureThe Secretary alleges in citation item 1a that Collier-Keyworth violated section1910.95(a) by failing to enforce the use of hearing protection equipment. In item 1b, healleges that the company violated section 1910.95(b)(1) by failing to implement feasibleadministrative or engineering controls to reduce noise exposures.[[28]]A. Personal Protective Equipment–Subsection 1910.95(a)Citation items 1a(A) and (C) concern the alleged failures by the three employees to wearpersonal hearing protectors. Industrial hygienist Hart observed LeBlanc and Melansonwearing earmuffs and Sund wearing Swedish wool earplugs during her inspection. Harttestified, however, that she also observed the employees \”at one time oranother\” not wearing hearing protection. The Secretary relies on Hart’s testimonythat she observed the employees without heating protection to support his allegation undersection 1910.95(a).The evidence does not prove that Collier-Keyworth violated section 1910. 95(a). Under thestandard, employees may be exposed to noise levels less than 115 dBA for some period oftime without using protective equipment. Also, at various times the three employees weresubjected to noise levels less than 90 dBA, where no protection is required regardless ofthe length of exposure. Thus, Hart’s testimony that she observed the employees at timeswithout protection does not prove a violation of the standard. If anything, the evidencethat the employees were sometimes observed wearing hearing protection tends to show thatCollier-Keyworth complied with section 1910.95(a). We therefore vacate citation items1a(A) and (C).B. Engineering Controls–Subsection 1910.15(b)(1)The Secretary alleges in citation item 1b(A) and (C) that Collier-Keyworth violatedsection 1910.95(b)(1) by failing to implement feasible engineering controls on presses2208, 2210, and 2216.[[29]] His expert witness on engineering controls, Dr. Barry,proposed two basic noise reduction techniques he believed were feasible: enclosing the dieareas on the presses; and replacing the existing air ejection nozzles with quieter ones.Each press forms metal parts by the force exerted by a rapidly descending die on sheetsteel in the bed of the press. Barry testified that there were two primary sources ofnoise associated with the operation of a press: (1) noise from the impact of the die onthe sheet metal stock; and (2) noise from the air ejection nozzles used to expel the partsfrom the press bed. Barry recommended isolating the press operators from these noisesources by installing acoustical enclosures around the die areas of the presses.[[30]] Hetestified that the enclosures would have to be designed \”to minimize any operatorencumbrances and allow for ease of die change.\” The enclosures, in Barry’s opinion,should be made of sheet metal, with transparent plastic panels to permit visualobservation of the die area. Doors and openings should be tightly sealed, and the insideof the enclosure should be lined with acoustically absorptive material to prevent soundbuildup. Barry believed that each press enclosure would cost $3,500 to $4,000 to design,fabricate, and install, and that a reduction in noise level of 10 dBA could be achieved.Barry had seen similar enclosures in use at another company’s plant and believed thoseenclosures achieved a 10 dBA reduction without inhibiting production.The enclosures Barry recommended would enclose the air ejection nozzles as well as the dieimpact area, and would therefore reduce noise from both sources. Barry also testified thatthe air noise could be reduced even if the die areas were not enclosed. Either quieternozzles that were commercially available could replace the existing nozzles, or thevelocity of air from the existing nozzles could be reduced to lessen the noise. Barrystated that the commercial nozzles would cost $5 to $20 each and would, in his opinion,produce a significant reduction in the noise level.Curtis Holmer, a noise control engineer who testified for Collier-Keyworth, did notbelieve that enclosing the die areas of the presses would significantly reduce the impactnoise emanating from the presses. Holmer testified that enclosing the die area cansignificantly reduce the noise from a press only when the force the press exerts isconsiderably below its capacity. However, when a press is used at or near its capacity, asthe presses were at Collier-Keyworth, then most of the energy of the impact is transferredfrom the die area to the frame of the press, and most of the noise the press producesradiates from its frame instead of from the point of impact. Holmer therefore believedthat enclosing the die area alone, as recommended by Barry, would not reduce the noiseresulting from the impact of the die on the stock. The enclosures would reduce only theair ejection noise, and Holmer thought this noise reduction would be on the order of 3 dBAor less.Chief Engineer Cochran testifed that die enclosures would severely restrict theproductivity of the presses by increasing the time necessary for the operators to performany duty requiring access to the die area. Cochran reviewed the production reportsprepared by the operators for a four-week period to determine how often they needed accessto the die area. Estimating that each instance of access would require 30 extra minutes ifthe dies were enclosed, he calculated that the company would have lost 72 hours ofproduction over the four-week period, or about 950 hours for a year.[[31]] Since thecompany had no excess press capacity, it would have to purchase a new press to maintainits current level of production. According to Cochran, a new press would cost $55,000. Aplant addition to house the machine would cost an additional $18,000, and a new operatorwould have to be hired to run the machine at a cost of $24,000 per year. Cochran alsonoted that the data on which he based these estimates might under-state the number oftimes the operators needed access to the dies because the operators might not recordsituations that were now very easy to resolve, such as clearing out a piece of scrap fromthe die area.Regarding Barry’s suggestion that the existing air ejection nozzles be replaced withquieter ones, plant engineer English testified that the company had tried using quieternozzles in 1977 but that those nozzles reduced the air velocity below what was needed toeject the parts from the press bed. Curtis Holmer explained that quiet nozzles obtaintheir noise reduction by reducing the air velocity and by spreading out the air streamover a larger area. However, for small parts such as Collier-Keyworth made, much of theair from such nozzles would blow past the part and be ineffective in moving it.In Sherwin-Williams, 11 BNA OSHC at 2110, 1984-85 CCH OSHD at p. 34,702, the Commissionstated what the Secretary must prove to show a violation of section 1910.95(b)(1):To prove a violation, therefore, the Secretary must prove that proposed engineering andadministrative controls are both technologically and economically feasible. As the NinthCircuit recognized in Castle & Cooke, \”realism and common sense should dictatehow the Secretary may meet his burden of providing substantial evidence offeasibility.\” 692 F.2d at 650. After the Secretary proves that controls aretechnologically feasible, the burden of producing evidence shifts to the employer, who mayraise the issue of economic feasibility and go forward with evidence of the cost ofcontrols and personal protective equipment. The burden of producing evidence then returnsto the Secretary, \”who must establish that the benefit of the proposed engineeringcontrols justifies their relative cost in comparison to other abatement methods.\” Id.The ultimate burden of persuasion on the feasibility issue nevertheless remains with theSecretary.The Secretary clearly did not prove the feasibility of reducing the air ejection noise byinstalling quieter nozzles. Although quieter nozzles are commercially available,Collier-Keyworth had tried such nozzles several years before the alleged violation andfound that the reduced velocity of air they produced provided insufficient force to ejectthe parts from the die area. Thus, such nozzles would not accomplish their intendedpurpose and would be technologically infeasible.We also find that the Secretary failed to prove the feasibility of die enclosures. Theenclosures would produce a minimal benefit insufficient to justify their substantial cost.The enclosures Barry recommended would surround the die areas of the presses and isolatethe operators from the noise produced by the impact of the die on the stock and the noisefrom the air ejection nozzles. Barry believed that such enclosures could reduce noiselevels about 10 dBA. Collier-Keyworth’s expert, Holmer, testified that the enclosureswould produce only about a 3 dBA reduction. In Holmer’s view, the die enclosures wouldonly reduce the air ejection noise reaching the operators, and not the noise from the diestriking the stock.We give considerable weight to Holmer’s opinion. Holmer had lengthy experience in themeasurement and control of industrial noise and was a member of the lnstitute of NoiseControl Engineering, a national organization of competent noise control professionals. Heprovided a reasoned explanation for his conclusion that die enclosures on Collier-Keyworth’s presses would not substantially reduce impact noise and we find his testimonypersuasive. Barry’s opinion that enclosures could achieve a 10 dBA reduction is entitledto much less weight than Holmer’s. Barry’s training was primarily in measuring the effectsof noise on the human ear rather than the analysis and reduction of industrial noise byengineering means. Barry had not designed or implemented industrial noise controls and wasnot a member of the Institute of Noise Control Engineering. Moreover, Barry’s opinion wasbased only on his belief that die enclosures at another company had achieved a 10 dBAreduction. Holmer’s testimony indicates, however, that the noise reduction produced by adie enclosure depends on the degree of capacity at which the press is used. Thus,achievement of a 10 dBA reduction at another company, in the absence of evidence ofsimilar conditions, is a tenuous basis for believing that Collier-Keyworth could obtain acomparable reduction. We find that the die enclosures recommended by Barry would achieve areduction of about 3 dBA in the noise levels to which Collier-Keyworth’s press operatorswere subjected.A reduction of 3 dBA is significant (see Continental Can Co., 76 OSAHRC 109\/A2, 4 BNA OSHC1541, 1543 n. 8, 1976-77 CCH OSHD (P) 21,009, p. 25,253 n. 8 (No. 3973, 1976)), but itmust be balanced against the costs of engineering controls and considered in light ofother protective methods. See Sherwin-WiIliams, 11 BNA OSHC at 2110, 1984-85 CCH OSHD atp. 34,702. The other method that we consider here is the personal protective equipmentthat Collier-Keyworth’s employees now wear. Dr. Victor Hildyard, a medical doctorspecializing in diagnosis and treatment of diseases of the ear, testified that earplugsand earmuffs of the type used by Collier-Keyworth’s employees could reduce the noisereaching the employee’s inner ear by 30 dBA if worn properly. Even if loosely fitted, theequipment would reduce noise levels by 10-15 dBA. Thus according to Dr. Hildyard, a noisereduction of 10 dBA is readily achievable even if the performance of the equipment is farless than ideal. The highest time- weighted average sound level to whichCollier-Keyworth’s press operators was exposed was about 98 dBA.[[32]] Thus, ifengineering controls were not required at all, the personal protective equipment wouldvery likely meet Collier-Keyworth’s obligation under section 1910.95(b) to \”reducesound levels within the levels of the table.\” Yet, even if engineering controls wereinstalled, the employees would still have to wear the personal hearing protectors becausea 3 dBA reduction would not reduce noise to within Table G-16 limits. They would simplynot have to wear it for as long as they now must. Thus, installing die enclosures wouldnot eliminate the need for personal protective equipment but would only decrease theamount of time employees must wear it.The cost of the controls is, however, substantial. According to Barry, each enclosurewould cost $3,500 to $4,000 to design, fabricate, and install. Moreover, to maintain itscurrent level of production, Collier-Keyworth would have to purchase a new press for$55,000, and would incur additional costs associated with the new press, including a dieenclosure for that press as well. The new press would add a noise source toCollier-Keyworth’s plant and could result in additional noise exposure for some employees.On balance, we are not convinced that the benefits to be gained from the enclosuresjustify these costs. We therefore find that the die enclosures recommended by Barry werenot shown to be feasible and will vacate citation items 1b(A) and (C).Accordingly, we vacate citations item 1a(B) and (D), and 1b(B) and (D), which involveemployee exposure to impulse noise, unless the Secretary requests an opportunity within 15days of this decision to rebut officially-noted documents with evidence of the Secretary’sintent in 1969. We vacate items 1a(A) and (C) because the Secretary failed to show thatemployees were not wearing personal hearing protectors for the periods required. And wevacate items 1b(A) and (C) because the Secretary failed to show that proposed engineeringcontrols were feasible. The judge’s decision is therefore affirmed.FOR THE COMMISSION Ray H. Darling, Jr.Executive Secretary DATED: April 6, 1987Appendix1. The noise standard proposed by the ACGIH committee in 1968 stated in 1968 stated inpart:Average Sound Pressure\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A-Weighting \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Duration ofLevels Of Octave Bands\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Network of\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Exposure perwith Center Frequencies\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Sound Level\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Dayof 500, 1000, and 2000 Hz\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Meter_______________________________________________________dB\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dBA\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Hours85\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a092\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a04 – 890\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a097\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a02 – 495\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0102\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a01 – 2100\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0107\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0less than\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a01 hour_______________________________________________________These values apply to total time of exposure per working day regardless of whether thisis one continuous exposures but dies [sic] not apply to impact or impulsive type ofnoises.When the daily noise exposure is composed of two or more periods of noise exposure ofdifferent levels, their combined effect should be considered, rather than the individualeffect of each.\u00a0 If the sum of the following fractions:C1\\T1 + C2\\T2 + ……..Cn\\Tnexceed unity, then, the mixed exposure should be considered to exceed the threshold limitvalues[.] C1 indicates the total time of exposure at a specified noise level, and T1indicates the total time of exposure permitted at that level.The above limits do not apply to impulse or impact type pf noise.\u00a0 It isrecommended that exposure to this type of noise should not exceed 140 dB peak soundpressure level.Appendix 1 of Herbert H. Jones, \”ACGIH’s Proposed Threshold Limit Value forNoise,\” 29 AM.\u00a0 Indus. Hygiene J. 537-40\u00a0 (Nov. – Dec. 1968)(ACGIH).2. A paper cited by both the Inter-Society Committee and the ACGIH Committee and thatproposed criteria for steady noise concluded with the following observation : We have purposely omitted any discussion of impulse noise up to now, for very soundreasons. We know very little about the effects of impulse noise on the ear. We have juststarted an intensive study of the relations between impulse noise and TTS (temporarythreshold shifts, a form of hearing loss).The problem does not lend itself to easy solution, for several reasons. Measuring impulsenoise is difficult to begin with, but not nearly as difficult to resolve as determiningthe effect the middle ear muscles have on the transmission of impulsive noise across themiddle ear. Limited laboratory research indicates that the laws governing TTS fromexposure to steady noise (non-impulse) do not operate for impulsive noise exposure.Actually, this should not be surprising, since the response of the basilar membrane tosteady noise and to impulse noise should be completely different.For the present, we can only say that no one should be habitually exposed to impulse noiseof any considerable magnitude without the use of hearing conservation measures.Our very limited knowledge of the effects of impulse noise prevents any meaningfuidiscussion of impulsive-type noise exposure.A. Glorig, W.D. Ward, & J. Nixon, \”Damage Risk Criteria and Noise-Induced HearingLoss,\” 74 Archives of Otolaryngology 413, 423 (Oct. 1961), cited in I-S at 424 ref.16; and ACGIH at 539 ref. 6 (article) and at 540 ref. 6 (proposed standard).3. A later report by a subcommittee chaired by Dr. Glorig proposed criteria for hearingconservation with the following caveat:Our knowledge of the relations of hearing loss to noise-exposure permits us to proposeguidelines for establishing standards for preventing significant noise- induced hearingloss in the majority of exposed persons. These recommended standards have been proposed bythe International Organization for Standardization. They are presented below in briefmodified form. They do not apply to exposure to impulsive noise but only to steady noise.Subcommittee on Noise, Committee on Conservation of Hearing, Am. Acad. of Ophthalmologyand Otolaryngology, Guide for Conservation of Hearing in Noise 13 (1964) (emphasis inoriginal), cited in I-S at 424 ref. 9.4. A 1966 publication of the American Industrial Hygiene Association reviewed the criteriafor recommended noise limits that had been proposed by various investigators up to thattime. While noting that there was little disagreement as to the levels of continuous noisethat were harmful, the publication went on to say:Much more difficult will be the selection of mandatory protection levels for intermittent,short duration, and impact noises . . . . Because there is still much to be learned aboutthe relationships between temporary and permanent threshold shifts the criteria for briefexposures cannot be expected to have the same reliability as those for continuousexposures. Until more is known about short-time exposures, the criteria should be treatedas temporary benchmarks and be used with considerable judgment.Am. Indus. Hygiene Ass’n., Industrial Noise Manual, ch. 7, at 59-60 (2d ed. 1966), citedin I-S at 424 refs. 3 & 13; and ACGIH at 540 ref. 3 (proposed standard).5. A 1967 paper by Coles et al. summarized studies that had tried to assess damage riskfrom impulse noise exposure. R. Coles, G. Garinther, D. Hodge, & C Rice, Criteria forAssessing Hearing Damage Risk From Impulse-Noise Exposure, U.S. Army Tech. Memo.13-67(Aug. 1967), cited in ACGIH at 539 ref. 12 (article).[[33]] These studies tended to seekpermissible exposure criteria in terms of factors unique to impulse noise. Several of thestudies demonstrated that exposure to 25-100 impulses in the 140-170 dB range at 6-30impulses per minute could produce temporary threshold shifts (\”TTS\”)[[34]] in asignificant number of exposed persons. The variations in the TTS’s of people exposed tosuch impulse noise was greater than among subjects exposed to steady-state noise,indicating that some people may be particularly susceptible to impulse noise. Responseswere observed to vary depending on whether the noise reached the ear at normal or grazingincidence; in some instances, for example, noise from a gun fired by a person near thesubject, which would reach the subject’s ear at normal incidence, appeared more harmfulthan noise from a gun fired by a subject himself, which would reach his ear at grazingincidence. TTS’s were greater for longer duration impulses of similar peak intensity, aresult probably attributable to the greater energy associated with the longer impulses.The paper drew from the studies criteria for peak pressure level and duration limits thatwould not produce an excessive risk of hearing loss. It concluded that impulses in the155-160 dB peak intensity range were safe for a duration of about 10 milliseconds, withhigher intensity impulses permissible for shorter duration’s and lower intensity impulsespermissible at longer duration’s.6. In a slightly later paper, the same authors noted that it was customary in proposingdamage risk criteria for steady-state noise to exclude impulse noise by implication ratherthan by direct statement. R. Coles, G. Garinther, D. Hodge. and C. Rice, \”HazardousExposure to Impulse Noise,\” 43 J. Acous. Soc. 336 (1968), cited in ACGIH at 539 ref.11 (article). After discussing risk factors associated with common amounts of exposure togunfire, the paper said, \”the more industrial types of impulse-noise exposure as inriveting, pile driving, drop forging, etc., may require a separate criterion or may betreatable by steady-state noise criteria.\” Id. at 339. However, the authorsconcluded:[w]hether a more general continuity between impulse and steady-state noise criteria canever be achieved seems very uncertain in view of the evident differences in their rangesof TTS and of opinion such as that of Kryter and Garinther that PTS from impulse noise mayfollow a different pattern from PTS due to steady-state noise.Id. at 343 (reference omitted).7. Investigators attempted to determine the combined effect of impulse noise andsteady-state noise in only one cited study. A. Cohen, B. Kylin, and P. LaBenz, TemporaryThreshold Shifts in Hearing From Exposure to Combined Impact\/Steady-State NoiseConditions, 40 J. Acous. Soc. 1371 (1966), cited in ACGIH at 539 ref. 10 (article). Anexperiment was conducted on 15 subjects, who were exposed to a variety of combinations ofimpulse and steady-state noise. The study found that, under some circumstances, impulsenoise in the presence of continuous noise was less harmful to hearing than the impulsenoise alone. The authors concluded that this was due to the \”acoustic reflex,\”which is a contraction of the middle ear muscles that attenuates the amount of soundtransmitted to the inner ear. If the acoustic reflex is activated before exposure to aloud impulse, the inner ear receives protection from the impulse. Therefore, when thesubjects were exposed to steady noise that was loud enough to activate the acousticreflex, the impulse noise was not as damaging as it otherwise would have been.8. The standard proposed by the Department of Labor under the Walsh-Healey Act onSeptember 20, 1968, at 33 Fed. Reg. 14259-60, stated:? 50-204.10 Occupational noise exposure.(a) The maximum permissible steady (or equivalent) noise level in the working environmentshall not exceed 85 decibels. Every employer shall utilize every feasible engineeringmethod to control noise levels. Such methods of control include reducing the amount ofnoise produced at the source, reducing the amount transmitted through the air, andsubstituting quieter procedures or machinery.(b) Where the noise is not steady the equivalent steady noise level is determined by thefollowing procedure: The duration over 1 week of each clearly distinguishable sound levelis located in column 1 of Table 1 following this paragraph (b) and the partial noiseexposure is read at the intersection of this row with the appropriate sound level column.The partial noise exposures thus obtained are added arithmetically. The sum is thecomposite noise exposure. The continuous noise exposure equivalent to the composite noiseexposure is then read from Table II next following Table 1. If the variations in noiselevel involve maxima at intervals of 1 second or less it is to be considered steady. Ifthe intervals are more than one second and the duration of the maxima are less than 1second each, maximum is to be considered as 1 second.TABLE I..\u00a0 Duration \/WeekThe table referred to above is not available in this format. Please telephone the Review Commission Public Information Office, 202-5398, to request apaper copy:; TTY: 202-606-5386;\u00a0 FAX: 202-606-5050; e-mail: [email protected]\u00a0Table IIThe table referred to above is not available in this format. Please telephone the Review Commission Public Information Office, 202-5398, to request apaper copy:; TTY: 202-606-5386;\u00a0 FAX: 202-606-5050; e-mail: [email protected] OF LABOR,Complainant v.COLLIER-KEYWORTH CO.,RespondentOSHRC DOCKET NO. 80-2848APPEARANCES: Robert Yetman, Esq., for Complainant Douglas B. M. Ehlke, Esq., for RespondentDECISION AND ORDERThis is a proceeding pursuant to the Occupational Safety & Health Act of 1970, asamended (29 USC, sec. 651 et seq.) hereinafter called the Act. The Complainant allegesthat the Respondent has violated sec. 5(a)(2) of the Act (sec. 654) by not complying withthe Occupational Safety & Health standards.The Respondent is a corporation engaged in the business of manufacturing chair mechanismsand its business affects the commerce of the United States. The Respondent’s worksite at Gardner, Massachusetts, was inspected by the OccupationalSafety & Health Administration (hereinafter called OSHA) on or about April 9 – 18,1980.On or about April 28, 1980, the following Citation, together with Notice of ProposedPenalty, was issued against the Respondent: Citation #1, Items 1a – c, the seriousviolation of the standards at 29 CFR 1910.95(a), .95(b)(1), and .95(b)(3); respectivelyItems 1a, b and c of Citation #1.On May 16, 1980, the Respondent filed Notice of Contest to Items #1a-c of Citation #1 andthe penalty proposed therefor.In his post-hearing Brief, the Complainant withdrew item 1(c).The pertinent words of the standards and the Act are appended to this decision underappropriate titles. The basic issue is whether or not the Respondent’s employees wereexposed to noise exceeding the limits of Table C-16 of the standard at 29 CFR 1910.95(a).SINCE THE HEARINGS WERE HELD ON MARCH 23-27, JUNE 16-19, DECEMBER 8-11 [ALL IN 1981] ANDMARCH 23 and 24, 1982, THE 1981 TRANSCRIPT WILL BE REFERRED TO BY MONTH AND PAGE NUMBER[E.G., MARCH 225] AND THE 1982 TRANSCRIPT BY YEAR, MONTH, AND PAGE NUMBER BECAUSE SOME OFTHE TRANSCRIPT PAGES ARE NUMBERED THE SAME EVEN THOUGH THEY COVER DIFFERENT DATES.It was a very long and hard-fought case, involving many scientific treatises and experttestimony. Both attorneys are to be commended for their excellent preparation and the zealwith which they tried the case.PRELIMINARYUnless otherwise indicated, the word \”dosimeter\” [as used herein] refers to theGen Rad 1954 type 2 instrument used in the April inspection of the Respondent’s jobsite.The dosimeter has an integrator that \”counts\” the sound waves that constitutenoise; and it has a 5dB rate of exchange as distinguished from a 3dB one. A\”decibel\” is roughly understood as a unit for expressing the relative intensityof sound. The integrator may be \”slow\” [a time constant of 1 second] or\”fast\” [a time constant of 1\/8th of a second]. The slow integrator is consideredto be less accurate than the fast in following the quick noise…Tr. June 1147-1150.The jobsite was inspected in April of 1980. The machines cited punch presses [#’s 2208,2209, 2210 on the second floor annex, #0352 on the 4th floor, and #2216 on the 2nd floorof the steel warehouse] and two lathes [#6040 and #3E 3018, both in the torsiondepartment]. The sound levels were obtained through the use of a dosimeter operated by orunder the supervision of OSHA Industrial Hygienist Anne Hart.In measuring sound for the purposes of Table G-16 of the standard at 29 CFR 1910.95(a) -(b)(3), a dosimeter at slow response with a 5dB rate of exchange is used because thestandard mandates a \”slow\” response. The evidence indicated that a differentrate of exchange [e.g., 3dB] would not qualify as a \”slow\” response; but, on theother hand, a different rate of exchange might be more accurate for certain types ofsound. One of the issues in the case was whether the 5dB rate of exchange would disclosethe true level of sound if fluctuating or impulse [impact] noise were also present.\”Exchange rate\” is the relationship between noise level and duration. Toillustrate: a 5dB exchange rate means that the sound level can be increased by 5dB withevery halving of exposure duration.There are two sets of dates on which sound measurements were taken by the Complainant:those in April, to which OSHC Compliance Officers Goyda and Hart testified; and those inSeptember, to which sound expert Barry testified. The witness Rockwell took soundmeasurements in February of 1981; and the witnesses Jones, Kamperman, Holmer, Kundert, andBotsford apparently did not participate in actual measurements of the cited machines buttestified as sound experts.IMPULSE NOISEThe case required considerable evidence of a highly technical nature involving sound levelmeters, dosimeters, 3dB and 5dB rates of exchange, various kinds of noise, etc. A basicissue concerned impulse noise.Several questions about impulse [or impact] noise must be resolved:What is it? Did it exist in the cited machines? Was it accurately measured by thedosimeters used in the inspection? Should it have been included or excluded in thedosimeter readout to determine compliance with Table G-16? TESTIMONYGoyda The witness Goyda, who is an experienced and competent Compliance Officer, was a member ofthe OSHA inspection party. He monitored the dosimeter testing in April of the employee,Couture … Exh. C-1. I was impressed with his competence and honesty. I find that heaccurately reported the readout registered by the dosimeter, as recorded in Exh. C-1.Hart The witness Hart, who is an experienced and competent Industrial Hygienist, was in chargeof the April inspection of the jobsite. She calibrated the dosimeters used, directed theplacing of dosimeters on employees, and recorded or supervised the recording of theirreadouts … Tr. June 672 – 685. I was impressed with her competence and honesty. I findthat she followed proper procedures in testing and that she accurately reported thereadouts registered by the dosimeters, as recorded in Exh. C1 – 5.She testified that the testing instrument was a Gen Rad 1954 Type 2 dosimeter, slowresponse, A weighted…Tr. June 730, 733. She said that impulse noise is not supposed tobe included in the dosimeter measurement because the reading will be distorted and willinaccurately register higher … Tr. June 768-770. She also testified that there wasimpulse noise from press #0352…Tr. June 715, 716.Exh. C-1 – 5 reflect that the sound levels recorded during the April inspection rangedfrom 94 to 101.3dBA as related to Table G-16.Barry The expert Barry, who was called by the Complainant, was well-qualified … Tr. March 319- 324. Exh. C- 20. He testified that the effects of impulse noise are not supposed to beexcluded; and that Table G-16 has no relation to impulse noise and does not excludeit…Tr. March 512, 513, June 913, 914, December 902. He emphatically stated that thefindings of Compliance Officer Hart were reliable with correction factors that would notchange her conclusions; and that the type dosimeter used in her inspection was a suitableinstrument for measuring noise levels to determine OSHA compliance…Tr. June 952-958. Heconcluded that, even applying error factors, employees were still exposed to excessivenoise…Tr. December 984.However, Barry also testified that the dosimeter has been a controversial instrument inrecent years…Tr. March 517, 518. He said that dosimeters tend to register higherreadings than actual noise levels; and that, for the sounds typical here, the readingcould be higher by 4 or 8 decibels…Tr. June 953, December 939, Exh. R-60. He also saidthat the more impulse and the higher, the greater is the dosimeter’s error…Tr. June1008. He testified that a dosimeter’s readout might be inaccurate due to the slow responsesetting required by the standard because, where there are both steady and impulse noises,the dosimeter distorts on the high side; and that the use of both fast and slow modes ofresponse would be better testing procedure…Tr. June 925-928, 933, December 909, 910,917, 948. He suggested that, \”to measure it really properly, the standard would haveto be rewritten.\”…Tr. June 927. It had been his opinion [as he wrote in the OSHAField Officer’s Manual] that, where both continuous and impulse noise are present, theproper way to determine compliance with Table G-16 is to use the fast mode setting andrecord the reading between the impulses…Tr. June 922, 923, 1015-1019. He had alsoauthored an article in which he stated that the standard at 29 CFR 1910.95 \”sets thepermissible exposure level for non-impulse noise.\”…Tr. June 920. He acknowledgedthat he had said that Table G- 16 was intended primarily for non-impulse noise … Tr.December 904, 906, Exh. R-59, R-62.As concerns the 3dB and 5dB rates of exchange, he agreed that the readout would differdepending on which was used, resulting in a possible dosimeter overstatement inaccuracy of100 – 200 percent…Tr. June 934 – 937. He had also recommended a change in the dosimeterfrom a 5dB exchange rate to the use of a 3dB one \”and making no differentiationbetween the type of noises. In other words, integrate all noise as noise. And, use thatfor determining compliance or non- compliance.\”…Tr. June 943. While that suggestioncould be explained as referring to possible ambiguities in the standard, it could also beinterpreted as a belief that the standard does exclude some noise; otherwise, why the needto specify that all noise is included?Barry’s testimony also indicated that there was a discrepancy of several decibels betweenthe slow and fast modes when he measured the machines in question in his September visitat the Respondent’s jobsite…Tr. June 975 – 999, Exh. C-22. [On this point, the testimonyis germane to the difference between the slow and fast modes, if not on the merits of thecitation itself.] He also testified that, in that same visit, he found impulsivecomponents of noise in all the cited machines except one lathe … Tr. June 913, 955.Rockwell The expert Rockwell, who was called by the Respondent, was well-qualified … Tr. June1027 – 1031, 1131 – 1146, Exh. R-22. He testified that impulse noise [which is less than 1per second and fewer than 60 per minute] should be handled separately; and that it hasbeen OSHA policy since 1972 to exclude or edit out such noise in testing. He also quotedan OSHA regional office and Chapter 4 of the OSHA Field Manual to the same effect…Tr.June 1150 – 1154, 1291. He said that the type of dosimeter used in the April inspectionerroneously read out several decibels higher because of impulse noise that should havebeen excluded…Tr. June 1159, 1160. He pointed out that recognized authorities took thesame position… Tr. June 1161 – 1169, Exh. R-23. He also testified about tests he hadconducted in the Respondent’s plant in February, 1981, using both slow and fast responsedosimeters. The slow response one [the type used in the instant case] registered 5 – 14decibels higher than the fast … Tr June 1174 – 1207, Exh. R-25 – 33. He concluded thatthe dosimeter overestimates exposure in \”this\” type of environment [theRespondent’s jobsite] by 10 – 12 decibels over the actual exposure level… Tr. June 1195- 1202. He said that the use of a 5dB rate of exchange dosimeter resulted in inflatedexposure readings, grossly overestimated the true noise, and was an inaccurate instrumentfor impulsive or rapidly fluctuating noise… Tr. June 1200 – 1202, 1209, 1234, 1236. Hespecified errors of 10 – 15 decibels at each location that he tested… Tr. June 1287,Exh. R-33. It was his opinion that the instrument used could not substantiate theallegations, and that impact noise levels should be measured only with an impact meter oran oscilloscope… Tr. June 1252, 1296, Exh. R- 35.HolmerThe expert Holmer, who was called by the Respondent, was well-qualified … Tr. June 1298- 1310, 1479 – 1481, Exh. R-36. He testified that impulse noise should be eliminated indetermining compliance with the G-16 table… Tr. June 1456, 1457. 1515. He said that,because of the difference between the 3dB and the 5dB exchange rates, the Gen Rad 1954dosimeter used in the inspection would read higher than the actual noise level … Tr.June 1447, 1455, 1466, 1467. He said that such dosimeters invariably overestimate signalsfluctuating at the rate of 1 second or less; and that no dosimeter accurately recordsimpulse noise in the Table G-16 sense because the standard requires a 5dB exchange rate…Tr. June 1441 – 1443, 1456. He also said that, although dosimeters read lower than theorywould project, and a Gen Rad 1954 dosimer does not overestimate as badly as an\”ideal\” dosimeter would, it still overestimates by a factor of 10 whereas an\”ideal.\” one would overestimate by 12…Tr. June 1467, 1471.Kundert The expert, Kundert, who was called by the Complainant, was well-qualified. . . Tr.December 778 – 780, Exh. C-27, C-28. He testified that the Gen Rad 1954 dosimeter wasdesigned specifically for testing against the OSHA standard, is excellent for thatpurpose, and can process short signals even though most dosimeters cannot. Although hesaid it was designed to measure both continuous and impulse noise, he acknowledged that itcannot accurately measure very short impulses but tends to produce low readings. . . Tr.December 795 – 797, 871 – 874. Concerning the 3dB and 5dB rates of exchange, he testifiedthat the dosimeter responds to impulsive sound as a 5dB instrument. . .Tr. December 863,864. Concerning the question of whether Table G-16 is interpreted to include or excludeimpulse sound, he testified that the OSHA field guide says to exclude it as did ANSIS-1.25. He concluded that, if impulse noise is to be excluded, the way to do it is byreading between the pulses, as the witness Rockwell did.. Tr. December 888 – 890. He alsosaid that the authorities cited in Exh. R-23 did not support Rockwell’s position but, onthe contrary, disagreed with it. . . Tr. December 798 – 803. Recalled by the Complainantin rebuttal he said that, for the type of impulsive noise here, the sound level meter anddosimeter give almost identical results; and that his in-court demonstration with thedosimeter and sound level meter (measuring a continuous sequence of impulses) produced thesame results. . . Tr. 1982 March 1728 – 1730, 1871 – 1876. BotsfordThe well-qualified expert, Botsford, who was called by the Respondent, testified that theDepartment of Labor had recommended the exclusion of impact noise from Table G-16, andimpact noise was not included in Table G-16. . . Tr. December 1038 – 1040, Exh. R-66.His testimony tended to establish that impact noise could not be accurately measured by asound level meter but should be measured by an impact meter againsta limit of 140 decibels; while continuous noise should be measured against Table G-16,using a time- weighted instrument with a 5 decibel exchange rate and then reading betweenthe impact peaks … Tr. December 1076 – 1080. He said that the OSHA field manualrecommends this procedure … Tr. December 1077, Exh. R-76. HildyardThe Respondent seemed to place great reliance on the testimony of Dr. Hildyard to theeffect that, although the advisory committee on OSHA standards made a final recommendationof priority for administrative and engineering controls over personal protective devices,the committee members had actually voted not to accord priority to administrative andengineering controls over personal protective devices [such as ear plugs] … Tr. March565, 583. However, even if there had been no objection to such testimony [and theComplainant did object to it], it would be given no weight because it violates the parolevidence rule [See Evidence ?1022, 1027 of 30 Am. Jur. 2nd; sec. 77.5 of Federal TrialHandbook; and Del Prete v. Board of Selectmen, 351 Mass. 344]. The official record of theadvisory committee on OSHA standards –which said administrative and engineering controlsmust be tried before personal protective equipment — governs and not evidence tending tocontradict it. Accordingly, I am limiting Dr. Hildyard’s testimony about the committeevote to whatever bearing it may have on the Respondent’s good faith.Jones The expert Jones, who was called in rebuttal by the Complainant, was a a well-qualifiedindustrial noise consultant. He testified that the sound level meter measures noise in theslow response better than the fast and that there is no basis for editing out impulsenoise…Tr. 1982 March 1629 – 1639. However, he also stated that he agreed with thestatement that only steady noise is to be measured against Table G- 16 … Tr. 1982 March1695. Although his name also appeared on a document apparently stating that Table G-16values do not apply to impulse noise, he testified that such use was unauthorized and didnot represent his opinion. . . Tr. 1982 March 1651 – 1658, 1668 – 1670. Because of hissworn testimony to that effect, I do not place any reliability on that document as far asit concerns any opinion by him.Jones also testified that Botsford had written an article in which he said impulse noiseshould be included in measurements of industrial noise. . . Tr. 1982 March 1637, 1638.Kamperman The expert Kamperman, who was called in rebuttal by the Complainant, was a well-qualifiedindustrial noise expert. He testified that the dosimeter is a very accurate instrument formeasuring noise in an industrial setting; that it always underestimates noise, and he hadfound no dosimeter that read high. . . Tr. 1982 March 1902, 1947, 1984. He also said thatimpulse noise should not be excluded from measurements and that industry custom is toinclude it in computing noise for purposes of Table G-16. . . Tr. 1982 March 1913 – 1917.He pointed out that if impulse noises are edited out of a punching operation, there wouldbe no noise left because they are all impulsive signals. . . Tr. 1982 March 1898, 1911. Hesaid that his field testing of the 1954 Gen Rad dosimeter and a sound level meter producedapproximately the same results, whether with or without impulse noise. . . Tr. 1982 March1900, 1901. He also said that the fast response is not as good as the slow in determiningnoise per Table G-16. . . Tr. 1982 March 1902. He concluded that he had never said thatimpulse noise should only be measured in accordance with the 140dB peak, and had neversaid that impulse noise should be excluded from measurements. . . Tr. 1982 March 1984,1985.However, when he was asked if he had said that \”it is not possible for a simpledosimeter to correctly compute the noise dose using a 5dB exchange rate for noises thatvary in levels of less than 10 seconds,\” his answer included statements that\”problems come because of the OSHA 5dB exchange rate. . . because the 5dB exchangerate violates basic laws of physics\”. . . Tr. 1982 March 1960 – 1966. He alsotestified that the dosimeter \”has a hard time correctly measuring anything other thansteady random noise\” and that he is \”on the committee to revise this standardnow to make dosimeters capable of correctly measuring impulsive sound.\”. . . Tr. 1982March 1945. He also conceded that there is \”confusion\” over the measurement ofimpulsive noise in the industrial environment and that he had written an article statingthat the standard only addresses the measurement of continuous noise. . . Tr. 1982 March1948, 1949, Ex. R-110. He also testified that he had made a written statement that, forimpulsive noise, \”the dosimeter will always indicate a much higher dose that thesound level meter\” and that the disparity would be 100% or a difference of 5dB. . .Tr. 1982 March 1953, 1954, 1968, 1970. While he also testified that this was an incorrectinterpretation of his view, he nevertheless conceded that he had told a seminar that\”dosimeters used in the noise environment typically found in metal fabricatingfacilities would read between 5 and 13dB too high, two to six times the expected noisedose relative to the OSHA 5 decibel exchange rate.\”. . . Tr. 1982 March 1953 – 1957,1968-1970.DISCUSSIONWith very minor differences, the experts all seemed to be in general agreement thatimpulse noise is a sound of brief duration that occurs less frequently than one a secondand less than 60 a minute; and includes such examples as hand clapping, dropping a book,firing a rifle, the ram of a punch press, etc. It is also clear that all the citedmachines [with the possible exception of the lathes] had impulsive components in thenoise. . . Tr. March 311, June 913, 921, 955, 956, 1150, 1251. As indicated above in this decision, the experts differed in their opinions on theaccuracy of the measurements by the dosimeter. Rockwell, Holmer, and Botsford were firm intheir conclusions that the dosimeter had to be inaccurate because of the standard’srequirements that only the slow response may be used. Although Barry, Kundert, Jones and Kamperman concluded that the dosimeter readouts wereaccurate, they did make many concessions [specified above] that tended to establish therewere distortions by the dosimeters used in the April inspection.In my opinion, the weight of the evidence clearly establishes that the dosimeters usedwere certain to overstate the employees’ exposure to noise. I so find.The most troublesome question is whether impulse noise should be included or excluded fromthe dosimeter readout. The standard itself merely uses the words \”noise\” or\”sound\” except for the word \”continuous\” in paragraph (b)(2). TableG-16, with figures going only as high as 115, has a footnote: \”Exposure to impulsiveor impact noise should not exceed 140dB peak sound pressure level\”. The standard at.95(b) 1 – 3 clearly mandates that sound levels be \”measured on the A scale…at slowresponse\”. Table G-16 also specifies: \”Sound level dBA slow response\”. TheCompliance Officer has no choice: the standard must be obeyed. The dilemma is that thestandard mandates the use of the slow response mode of testing, but the evidenceestablishes beyond doubt that, when impulsive noise is present, the slow response moderesults in an inaccurate readout in excess of the true noise level.Even if the use of the slow response dosimeter results in distorted readings, is thequestion of compliance to be based on such figures? It is hard to believe that any branchof government would intend such a result. Certainly a judicial forum could not condone anydecision based on inaccurate facts.The Complainant has the burden of proving that the Respondent’s employees were exposed tonoise that exceeded the amounts specified in Table G-16. In my opinion, that calls for theComplainant to prove that there were actual and true noise levels in the amounts stated inTable G-16, and not merely readout figures provided by the mandated slow responsedosimeter. I find that that is the Complainants burden of proof even if it means that theCompliance Officer has to use two sets of instruments: one to comply with the mandate ofthe OSHA standard and a second to satisfy the demands of proof and due process of law.A third alternative, of course, is for some modification of the standard (or Table G-16)in conformity with the most acceptable technology available [a need recognized by theComplainant’s very experienced expert, Barry… Tr. -June 927]. I strongly recommend suchmodification because it is a scandalous situation when the various entities concerned withsafe working conditions — OSHA, the employer and employees, the Complainant and theRespondent, the attorneys, and the judicial forum itself — are all at the mercy of asystem that practically guarantees controversy and uncertainty — because even the expertsthemselves are in almost total disagreement.If the present state of the law requires the use of instruments in addition to any thatare mandated by the standard, or calls for measures to correct the readout figures, ormakes the Complainant’s task more difficult in any way, that is unfortunate; but theComplainant has the burden of proving its allegation.On the question of the accuracy of the slow response dosimeter when impulse or impactnoise is present at the jobsite, there may be a conflict of testimony between the expertsfor the Complainant and the experts for the Respondent. Assuming that all are equallyhonest and equally well-qualified [and I find them so to be] has the Complainant carriedhis burden of proof? I find that the dosimeter’s accuracy has not been established; in fact, quite to thecontrary, its inaccuracy was proven. The testimony of the Respondent’s experts to thateffect was not shaken: and the Complainant’s experts [Barry, Jones, Kundert. andKamperman] also made several statements tending to the same conclusion. The inspectionofficer herself (Hart) also agreed that the dosimeter readout would be inaccurate whenimpulse noise was included. In that state of the evidence, I find that the dosimeter’saccuracy was not proven. On the question of whether to include or exclude impulse noise in determining compliancewith Table C-16: 1 find it should be excluded. In the first place, its inclusion was thebasic cause of the dosimeter’s inaccuracy in the instant case. Secondly, I find that itwas the customary practice for OSHA to exclude impulse noise in determining thepossibility of noise exceeding the figures in Table G-16. The uncontradicted testimony ofthe expert Rockwell was that it has been OSHA policy since 1972 to exclude such noise; andthat Chapter 4 of the OSHA Field Manual is to the same effect…Tr. June 1150 – 1154,1291. Hart’s testimony that impulse noise was not supposed to be included corroboratesthat conclusion.The Respondent has a constitutional right to be treated the same as any other employercited under the same standard. If the customary practice of OSHA was to exclude suchimpulse noise, it should have been excluded in the instant case.Lastly, I find that any reasonable interpretation of Table G-16 leads to the conclusionthat impulse noise must be excluded. An analysis of the standard can lead to no otherconclusion. We begin with the assumption that it was intended to have a workable standardwith accurate figures in Table G-16 — and the standard should be interpreted to achievethose ends. The standard clearly and explicitly states that the slow response mode must beused — but that mode cannot accurately measure impulse noise. The standard is soambiguous about impulse noise that (in my opinion) reasonable persons would agree that twointerpretations are possible: (1) that impulse noise should be included in the dosimeterreadout; or (2) it should be excluded. The first interpretation [including impulse noise]results in an inaccurate readout. Consequently, the more reasonable conclusion is toexclude impulse noise since that is the only interpretation that gives accurate figures inthe readout while still complying with the slow response mode, as mandated by thestandard. That is the only interpretation that gives a workable standard with accuratefigures in Table G-16.In the final analysis, the Complainant has not proven its case whether impulse noise issupposed to be included or excluded. If it should have been excluded, that was not donehere; and if it should have been included, it results in an inaccurate readout. In eitherevent, the dosimeter used was not a reliable instrument on which to base the citation.The difference between the true sound level and the dosimeter’s inaccurate readout was notminor but amounted to at least several decibels. When the dosimeter’s readout ranged from94 to 101.3 decibels, an error of several decibels could easily bring the true figures tothose in compliance with Table G-16. While an error of several decibels might not be ofany significance if the dosimeter readout were greatly in excess of the figures in TableG-16, it becomes of paramount importance when [as here] the readout ranges from 94 to101.3 decibels.Where the noise is so excessive that an error of several decibels in the dosimeter iscomparatively trivial, the inaccuracy becomes immaterial. For example, in the Frank Nuttycase [5 OSHC 1727], where the recorded noise was 8 times more than that permitted in TableG-16, the Review Commission affirmed without review the decision of the Administrative LawJudge that the Respondent had not complied with the noise standard concerned. [Althoughthe dosimeter was held to be adequate in that case, I find it easily distinguishable fromthe instant case]. Here, where the alleged excessive noise is comparatively slight and thedosimeter error comparatively great, it must be found that the Complainant has not provenexcessive noise.Offers of Proof by the ComplainantEven assuming the admissibility of the evidence in the Complainant’s various offers ofproof, the quantity and quality of evidence casting doubt on the reliability of thedosimeter is not diminished. If the proffered evidence had been admitted, it would notchange my findings.Barry’s testimony of September inspectionIn seeking to establish the admissibility of Barry’s testimony concerning his September,1980, visit to the jobsite, the Complainant offered the testimony of Compliance OfficerGoyda that the conditions prevailing at that time were similar to those of the officialinspection in April, 1980. The substance of Goyda’s direct examination was that themachines and the parts produced appeared to be the same on both dates and he observed nodifference in them … Tr. March 29 – 31, 299 – 302. He took no measurements but describedthe parts in fairly general terms. He testified that he heard the noise emitted by themachines and it was \”the same\” on both dates … Tr. March 303.Cochran, the Respondent’s chief engineer, testified that the punch presses used some 20 -30 difference dies of varying weights, shapes, and thickness in producing 30 differentcomponents or parts. The weights vary from 200 to one thousand pounds in sizes rangingfrom 8 x 10 inches to 22 x 16 inches…Tr. March 103 – 108, 122. He said the manner inwhich the machines are operated changes every day; and the number of parts and the lengthof the run vary with the particular job…Tr. March 112 – 114, 171. That is also true ofthe machine’s number of strokes per minute…Tr. March 130, 149 – 151. He testified thatthe parts made by machines 2208 – 2210 \”are all different\” and that the twoparts made on April 14th [the inspection date] were not like the two parts made onSeptember 15th [the date of Barry’s visit] but were \”4 absolutely differentparts\” . . . Tr. March 287. He explained that, although the machines themselves wereidentical, the operation was not \”because it had a different tool in it and everytool runs differently. . . not the same steel strip. . . a different width and fed adifferent length.\”. . . Tr. March 289. He also pointed out that there would be\”a wide variation\” in the noise because the gauge of the material is \”onefactor that is involved in producing noise when that die hits the stock\”. . . Tr.March 291, 292. He also testified that there were different sounds on the lathe on somedays. . . Tr. March 128.Bergeron, the Respondent’s assistant director of manufacturing, testified that dies may ormay not be changed frequently because it is a job shop. . . Tr. March 226 – 229.There was no contradiction of the testimony of Cochran and Bergeron on the differences indies, parts, strokes, and length of run. Moreover, I was favorably impressed by the candorand honesty of both witnesses; and both certainly were in positions to know about theoperations they described.It was ruled that, on the basis of Goyda’s testimony that conditions during the April andSeptember visits were similar, Barry’s testimony about his September visit was technicallyadmissible; but both parties were alerted to the fact that it would be given very littleweight. . . Tr. March 303 – 307. My opinion was [and is] that in a matter as sensitive anddelicate as the determination of decibels of noise, more is required than Goyda’s mere eyeand ear observation of the appearance and sound of machines and parts. The testimony ofBarry about his September visit was admitted because, technically, Goyda’s testimonyfurnished a foundation of similarity. I have given it very little weight because,substantively, Cochran’s uncontradicted testimony established that the difference in dies,parts, strokes, and lengths of run may well have resulted in different noise levels.REVIEW COMMISSIONIn view of my findings concerning the inaccuracy of the dosimeter, I have not reacheditems 1(b) and 1(c) of Citation #1. I purposely have not made alternative findings becauseit seems to me to be of over-riding importance for the Review Commission to clear up theuncertainties arising out of the possible interpretations to which the standard at 29 CFR1910.95 is susceptible. I respectfully request that my decision be reviewed to that end.[As cited above, I am aware of the Frank Nutty case interpreting a virtually identicalnoise standard. However, I think that decision is not only distinguishable in severalaspects from the instant case but, of great importance, the point raised here was notdiscussed there.]FINDINGS OF FACTHaving heard the testimony, observed the witnesses, and examined the exhibits, thefollowing Findings of Fact are made:1. At all times concerned, the Respondent regularly received, handled or worked with goodswhich had moved across state lines.2. As concerns Items #1(a) of Citation #1, the dosimeter used in the inspection did notaccurately record the true sound levels.3. The true sound levels did not exceed the figures of Table G-16.4 The sound levels exceeded those shown in Table G-16 when measured on the A scale of astandard sound level meter at slow response.CONCLUSIONS OF LAW1. At all times concerned, the Respondent was an employer engaged in a business affectingcommerce within the meaning of the Act; and the Occupational Safety & Health ReviewCommission has jurisdiction over the subject matter and the parties.2. The Complainant has not sustained the burden of proving the Respondent violated thestandard at 29 CFR 1910.95(a).ORDER The whole record having been considered, it is ordered that Citation #1, and the penaltyproposed therefor, be vacated.SO ORDERED.FOSTER FURCOLO JUDGE, OSHRCDated:June 28, 1982 Boston, MassachusettsAPPENDIX THE ACTSection 654\u00a0\u00a0\u00a0\u00a0 [section 5(a)(2)] Employer \”…shallcomply with occupational safety and health standards…\”Section 666\u00a0\u00a0\u00a0\u00a0 [section 17(b)] \”…employer who hasreceived a citation for a serious violation … of this Act…shall be assessed a civilpenalty of up to $1,000 for\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 eachsuch violation.\” Section 666\u00a0\u00a0\u00a0\u00a0 [section 17(k)] \”…a serious violationshall be deemed to exist…if there is a substantial probability that death or seriousphysical harm could result …\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 unlessthe employer did not, and could not…know of the presence of the violation.\”THE STANDARDS29 CFR 1910.95(a) – (b)(3);? 1910.95 Occupational noise exposure. (a) Protection against the effects of noise exposure shall be provided when the soundlevels exceed those shown in Table G-16 when measured on the A scale of a standard soundlevel meter at slow response.(b)(1) When employees are subjected to sound exceeding those listed in Table G-16,feasible administrative or engineering controls shall be utilized. If such controls failto reduce sound levels within the levels of Table G-16, personal protective equipmentshall be provided and used to reduce sound levels within the levels of the table.(2) If the variations in noise level involve maxima at intervals of 1 second or less, itis to be considered continuous.(3) In all cases where the sound levels exceed the values shown herein, a continuing,effective hearing conservation program shall be administered.TABLE G-16 – PERMISSIBLE NOISE EXPUSURES[[1]]Duration per day, hours\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Soundlevel dBA slow\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 response8 ……………………………………………………………………….\u00a0\u00a0 906 ……………………………………………………………………..\u00a0\u00a0\u00a0\u00a0 924 ……………………………………………………………………..\u00a0\u00a0\u00a0\u00a0 953 ……………………………………………………………………..\u00a0\u00a0\u00a0\u00a0 972 ……………………………………………………………………\u00a0\u00a0\u00a0\u00a0 1001-1\/2 …………………………………………………………….\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1021 …………………………………………………………………..\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 105 1\/2 …………………………………………………………………\u00a0\u00a0\u00a0\u00a0\u00a0 1101\/4 or less ………………………………………………………\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 115[[1]] When the daily noise exposure is composed of two or more periods of noise exposureof different levels, their combined effect should be considered, rather than theindividual effect of each. If the sum of the following fractions: C1\/T + C2\/T2 Cn\/Tnexceeds unity, then, the mixed exposure should be considered to exceed the limit value. Cnindicates the total time of exposure at a specified noise level, and Tn indicates thetotal time of exposure permitted at that level.Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.FOOTNOTES: However, Ward noted that there was evidence in 1969 that impact noise should producehearing loss, but that the addition of impulse noise to a steady noise reduced the effectof noise on hearing, and in other cases, enhanced the effect; in other cases there was noeffect (II, p.379).[[1]] The standard is quoted in its entirety except for provisions dealing withdetermining noise levels by octave band analysis, a measurement technique not involved inthis case.[[2]] This problem was noted early in the Commission’s experience with the noisestandard. See Weyerhaeuser Co., 74 OSAHRC 57\/F4, 2 BNA OSHC 1152, 1153-54, 1974-75 CCHOSHD (P) 18,468, pp. 22,485-86 (No. 2116, 1974) (lead opinion); Sun Shipbuilding &Drydock Co., 74 OSAHRC 61\/A2, 2 BNA, OSHC 1181, 1182-83, CCH OSHD (P) 18,537 (No. 268,1974) (lead and concurring opinions); Weyerhaeuser Co., 77 OSAHRC 9\/A2, 4 BNA OSHC 1972,1974-75, 1976-77 CCH OSHD(P) 21,465, pp. 25,748-49 (No. 1231, 1977), aff’d in pertinentpart, sub nom. Noblecraft Industries, Inc. v. Secretary, 614 F.2d 199 (9th Cir. 1980).[[3]] Collier-Keyworth argues that the use of a dosimeter is inherently inconsistent withthe standard, which specifies that noise levels are to be measured with a standard soundlevel meter. As we have explained, the dosimeter itself contains the circuitry of astandard sound level meter. It also contains other circuitry, but the other circuitry onlyperforms automatically calculations that would otherwise have to be done manually. Thus,the dosimeter does precisely what the standard requires: measures sound levels with astandard sound level meter and performs the calculations required by the cumulationformula. Whether it performs those functions with sufficient accuracy is another question,which we will address later. For now, we note only that the use of a dosimeter isconsistent with the standard, and reflect Collier-Keyworth’s contrary arguement Love BoxCo., 76 OSAHRC 45\/05 4 BNA OSHC 1138, 1140 & n.2 1975-76 CCH OSHD ?20,588 p. 24,628& n2 (No.6286,1976).[[4]] In 1981, section 1910.95 (b) (3) was replaced with a new standard, known as the\”hearing conservation standard\” or \”hearing conservation amendment,\”which lists in detail the requirements a hearing conservation program must have. 46Fed.Reg 4078 (Jan. 16, 1981), now codified at 29 C. F. R. ? 1910.95 (c)-(p). The hearingconservation standard requires an employer to implement a hearing conservation programwherever employee noise exposures equal or exceed an eight hour time-weighted averagelevel of 85 dBA. 29 C. F. R. ?1910.95 (c) (1). It also provides that, in determiningwhether this limit is exceeded, \”[a]ll continuous, intermittent and impulsive sound levels from 80 decibels to 130 decibels should beintegrated into the noise measurements.\” 29 C. F. R. ? 1910.95 (d) (2) (i). Thus,impulse noise is explicitly included in the hearing conservation standard. However, inpromulgating the hearing conservation standard, the Secretary did not purport to amend anyprovision of the old standard except subsection.(b) (2) The hearing conservation standardtherefore does not affect whether impulse noise is included under the standard involved inthis case, section 1910.95 (a)-(b) (2), which require administrative and engineering noisecontrols and personal protective equipment.[[5]] The Secretary’s expert witness, Dr. Burton Jaffe, testified that noise is a\”mechanical transfer of energy that really shakes the hair cells and damagethem\”.The manner in which this testimony is summarized in the Secretary’s briefechoes what has become known as the \”equal energy rule,\” a theory that equalamounts of noise energy are equally harmful regardless of their form or duration. Thistheory was discussed at length in the preamble to the Secretary’s new hearing conservationstandard and expressly applied to impulse noise. See 46 Fed. Reg. at 4096. Its applicationto impulse noise seems to have been upheld on the basis of the rulemaking record compiledby OSHA to support the hearing conservation standard. See .Forging Industry Ass’n V.Secretary of Labor, 773 F.2d 1436, 1451 (4th Cir. 1985) (en blanc).[[6]] The Secretary attempts on the basis of a witness’s testimony to reconcile Table G-16with the 140 dB provision. We shall consider this testimony after have completed ourreview of the text of the standard. See note 12 below.[[7]] When the original version of the standard was published by the Labor Department’sBureau of Labor Standards under the Walsh-Healey Government Contracts Act, 41 U. S.C. ?35-45, this provision was set in the same size type as other text and placed after thefootnote to the table. See 34 Fed. Reg. 7949 (1969) and 35 Fed. Reg. 1015 (1970)(corrections to standard). When the standard was adopted and reprinted under the OSH Actin 1971, the Secretary did not support to–and was in any event not. empowered to–makeany substantive change in it. Yet, the 140 dB provision was then printed in the same smalltype as the footnote to the table, apparently because a typesetter mistook it to be acontinuation of the footnote to the table immediately above. 36 Fed. Reg. 10466, 10513(1971). We are confirmed in this impression by four Labor Department documents. The LaborDepartment’s own edition of OSHA standards, I General Industry Standards andInterpretations 144 (OSHA No. 2077, .1984), prints the 140 dB impulse noise provision in,and in the same size type as, the text. The 140 db provision is still part of the text ofthe original Walsh-Healey standard, 41 C.F.R. ? 50- 204.10. A Labor Department bulletininterpreting the Walsh-Healey standard characterized the provision as \”[t]he lastsentence in paragraph (d) of section 50-204.10 . . . . \” Bureau of Labor Standards,U.S. Dept. of Labor, Bulletin 334, Guidelines to the Department of Labor’s OccupationalNoise Standards for Federal Supply Contracts, 4 (Dec. 4, 1970). Finally, the correspondingprovision in OSHA’s noise standard for the construction industry– which adopted at aboutthe same time as the original general industry standard (see 36 Fed. Reg. 7340, 7348(1971))–was printed in a separate subsection, now codified as 29 C.F.R. ? 1926.52(e)[[8]] That provision states in part that \”[w]hen an agency decision rests on officialnotice of a material fact not appearing in the evidence of the record, a party isentitled, on timely request, to an opportunity to show the contrary.\”[[9]] The record contains various terms used to describe non-impulsive noise, such assteady noise, continuous noise, steady-state noise, and intermittent noise. Except forintermittent noise, these terms suggest noise that is constant in intensity over arelatively long period of time. Intermittent noise varies in intensity, but not as rapidlyas impulse noise. For example, noise from a machine that is alternately on and off forseveral seconds at a time would be classified as intermittent noise.[[10]] Even in 1981, when the Secretary promulgated the hearing conservation amendment tothe noise standard, there was a relative dearth of information on impulse noise.\u00a0 TheSecretary noted: \”In contrast to the studies of continuous noise mentioned above,dose-response relationships for impulse noise are not so easily defined.\” 46 Fed.Reg. at 4096.ACGIH, \”Threshold Limit Values of Physical Agents\” (1969), reprinted in NationalSafety Council, Fundamentals of Industrial Hygiene, Appendix A,\u00a0 pp.739-41 (1971).Collier-Keyworth introduced as Exhibit R-101 the 1971 version of the ACGIH standard, whichappears to be identical..[[12]] See also a chapter by Jones, \”Standards and Threshold Limit Values forNoise,\” in National Safety Council, Industrial Noise and Hearing Conservation ch. 11,p. 309 (Olishifski & Harford eds. 1975)(ACGIH limits \”incorporated in\”Walsh-Healy standard). That the ACGIH standard substantially influenced the drafters ofthe\u00a0 Walsh-Healy standard leads the Secretary to rely heavily on testimony by Jones,who was chairman of the ACGIH committee, that the table in the ACGIH standardcorresponding to Table G-16 \”would include anything that the sound level meter wouldrespond to, be it a continuous[,] impact [or] impulsive noise.\” Jones furthertestified that the 140 dB impulse noise provision was intended to be an additionalrestriction on impulse noise, included because of the possibility that high intensityimpulses could be harmful even if the limits in the table were not exceeded. The Secretarystates that Jones \”was, in effect, the author of the [140 dB impulse noise]provision\” because the limits in the table adopted by Jones’s ACGIH Committee were\”issued in virtually identical form by the Department of Labor as a standard underthe Walsh- Healey Act. . . . .\” We are unable to credit this part of Jones’stestimony because the ACGIH standard expressly stated that the exposure limits in itstable do not apply to impulse noise. We therefore disagree with the argument in theSecretary’s brief that this part of Jones’s testimony is a reliable guide to the intent ofthe drafters of the Walsh-Healey standard.[[13]] The bulletin was revised on June 8, 1971, after the Walsh-Healey standard wasadopted under the OSH Act. The 1971 version was introduced into evidence.[[14]] A passage written by Dr. Van Atta in Industrial Noise and Hearing Conservation, n.12 above, at 322, also suggests this. The passage, which was read into the record, states:This regulation provides for a basic level of 90 dBA for continuous noise exposure with atradeoff of 5 dBA for each halving of the noise exposure time. This includes a roughallowance for interruptions of noise exposure. Impact noises must be limited to less than140 dB peak sound pressure level.It is important to note that this is a double requirement. For example, in a power-pressdepartment, it is necessary that both the instantaneous peaks of the impact noises arisingout of the operation of large presses be below 140 dB and that the continuous ambientbackground noise be below 90 dBA. [Emphasis added.][[15]] J Barry, \”Problems in Enforcement of the Occupational Noise Standard,\”in Proceedings of Noise-Con 79, Machinery Noise Control, 11 (Sullivan & Crocker eds.1979). At the hearing in this case, Dr. Barry first testified that Table G-16 \”has norelation in impulse noise.\” He later stated, however, that the standard did intendfor impulse noise to be included in dosage calculations. [[16]] The chapter is printed in Occup. Safety and Health Admin., U. S. Dep’t of Labor, VIOSHA No. 3058, Industrial HygieneField Operations Manual (1980), and in CCH Employ, S.& H. Guide, Edition No. 419 (May 24, 1979). [[17]] At the hearing in this case, Dr. Barry stated that he recommended the use of fastresponse in this instruction to enable the inspector to analyze the components of thenoise to assist in evaluating the feasibility of engineering controls. (Fast response,like slow response, is a setting on a sound level meter. For the moment it is enough toobserve that where impulse noises are closely spaced, fast response is more accurate thanslow response in displaying the true background noise level.) When the Secretarypromulgated the hearing conservation amendment in 1981, he said that this IHFOM provision\”is clearly at variance with the present standard and is being deleted.\” 46 Fed.Reg. 4078, 4137 & n. 11 (Jan. 16, 1981). If, as Dr. Barry stated, the purpose of theprovision was to assist inspectors to evaluate the feasibility of engineering controls,there would have been no need for the Secretary to disavow it in this manner. In sum, weread the instruction as OSHA did-to signify that impulse noise was not to be included indetermining whether employee exposure exceeds Table G-16 levels.The Secretary also claims that the prescription of slow response in the standard isinconsistent with any intent to exclude impulse noise from Table G- 16. We are unconvincedof any logical inconsistency here. The ACGIH standard–from which the Secretaryacknowledges the drafters of the Walsh- Healey standard drew heavily–both prescribed slowresponse and excluded impulse noise. The same is true of the noise standard proposed bythe Secretary in 1974. See 89 Fed. Red 37773, 37775 (Oct. 24, 1974), proposing new section1910.95 (c) (1) (ii). [[18]] Turner involved three presses in the same room. One stroked at a rate of 27 perminute, and a second at 33 to 38 strokes per minute. 4 BNA OSHC at 1556,1976-77 CCH OSHDat pp. 25,273-4. Thus, these two presses alone would produce 60 or more noise impulses perminute, i.e., continuous noise.[[19]] Collier-Keyworth occasionally alludes to this point in a confusing fashion,speaking of dosimeters having an \”effective exchange rate of 3 decibels. Adosimeter set to employ a 3 decibel exchange rate would register the same sound levels aswould one set to employ a 5 decibel exchange rate. It would record a higher dosage,however, because the lower exchange rate shortens permissible duration’s. Yet,Collier-Keyworth does not argue that OSHA set its dosimeters here to employ a 3 decibelexchange rate. Instead, it maintains, based on the testimony of expert witnesses, that inimpulsive noise environments dosimeters set to use a 5 decibel exchange rate and slowresponse will so overcount \”true noise levels\” as to approximate the results ofemploying a 3 decibel exchange rate with fast response. Collier-Keyworth’s argument restson the assumption that under Table G-16 sound levels must be measured with a fast responseinstrument. We will discuss the validity of this assumption in the text below.[[20]] This effect is illustrated by Ex. R-26, which contains several strip chartrecordings made by Rockwell, and by C-22L, a strip chart recording made by Barry. Onerecording in Ex. R-26 shows noise patterns for a power press operating at 100 strokes perminute. Because the peaks are less than one second apart, the noise is quasi-continuous.With the sound level meter set for fast response, which corresponds to in integration timeof an eighth of a second, the individual impulses are readily visible and have peakintensities of 108-109 dBA superimposed on a background of about 99 dBA. On slow response,however, the noise appears relatively continuous at a level of 104-105 dBA. Thus, comparedto fast response, the sound level meter at slow response reads higher troughs but lowerpeaks, that is, the individual impulses appear to be of longer duration but lower peakintensity.The reason for the difference is best explained by discussing the behavior of the needleof a sound level meter: At slow response, the needle does not have time to return to thecontinuous, background noise level before the next impulse comes along and caused it toswing back up. For example, in Ex. C-22L,the sound peaks are about two to three secondsapart, and hence much farther apart than in Ex R-26. The noise levels indicated by slowresponse are still different from that of fast response but not as different as in Ex.R-26, where noise peaks only six-tenths of a second apart gave the needle little time toswing back before the next impulse arrives.[[21]] Its argument is echoed in the observation of one dosimeter manufacturer that\”[i]t is the requirement of a slow response time constant in a dosimeter that causesa dosimeter to appear to read high.\” Ex. R-24, statement by Quest Electronics.[[22]] See American Mining Congress v. Marshall, 671 F.2d 1251, 1255-7 (10th Cir. 1982)(discussing whether measuring method prescribed by mine health regulation is arbitrary,capricious, or an abuse of discretion\” within the meaning of the AdministrativeProcedure Act).[[23]] The brief of the Chocolate Manufacturers Association, which the Commissionpermitted to appear on review as an amicus curiae, argues that dosimeters generally areunreliable. Attached to its brief are studies by Dr. Paul Hess of Hershey Foods that arguein support of this thesis and that criticize OSHA’s evaluation of Dr. Hess’s studies inOSHA’s preamble to revisions in 1983 of the hearing conservation standard. The ChocolateManufacturers Association also asks the Commission to take official notice of statementsin OSHA’s Industrial Hygiene Technical Manual, p. B-47 (March 30, 1984)(\”theIHTM\”), reprinted in CCH Employ. S.& H. Guide, Extra Edition No. 680 (May 24,1984), and in 2 BNA Occup. S.& H. Rep. 77:8001, 77:8925 (June 14, 1984). The Secretaryof labor objects to the Chocolate Manufacturers Association’s brief, arguing that itimproperly introduces evidence. We deferred ruling on this motion and on the taking ofofficial notice of the IHTM material.We take official notice of the IHTM but we are not persuaded that accepting its statementsas true mandates a result here. The portion of the IHTM relied on by the ChocolateManufacturers Association warns OSHA field personnel that \”[s]hort-duration pulseswith a low repetition rate may be completely eliminated from the dosimeter readings simplybecause the averaging circuits in the instruments cannot respond fast enough to the changein level.\” However, we understand this passage to mean that dosimeters sometimesundercount the noise level when certain impulses are present; moreover, if \”lowrepetition rate\” refers to impulses more than one second apart, then the supposedinaccuracy is irrelevant because we hold that such impulses may not be counted at all.Another passage relied on by the amicus states that \”[c]onversely, pulses with ahigher repetition rate may be overestimated by the dosimeter because the averagingcircuits will build up to the high level but will not have time to drop back down betweenthe pulses.\” We are puzzled by this passage, for it could be read to complain of theslow response mode mandated by OSHA’s own standard. In any event,if it refers to impulsesmore than one second apart, it is irrelevant for the reasons we have already stated. Andif it refers to impulses less than one second apart, then it is also irrelevant becauseunder subsection (b)(2), the dosimeter does not have to drop back down between impulses atall. Thus, we are not persuaded that the IHTM requires rejection of the dosimeter readingshere.On the other hand, we grant the Secretary’s motion to strike those portions of theChocolate Manufacturers Association brief that introduces the studies of Dr. Hess. Wedecline to take official notice of this material. The material attached by the amicus toits review brief is largely evidentiary, consisting of papers and studies by Dr. Hesschallenging the accuracy of dosimeters generally. As the Secretary argues, however, theauthor of this material has not been subjected cross- examination and the Secretary’scounsel has had no opportunity to evaluate, impeach or rebut his studies. Thus, if thisnew material were to be considered, a remand to Judge Furcolo would be in order. Yet, thisreopening of the record would be on the implied invitation of an amicus, not a party. Inthese circumstances, we adhere to our rule against the admission of evidentiary materialsin review briefs. E.g., Anoplate Corp., 86 OSAHRC , 12 BNA OSHC 1628, 1683, n.6, 1986 CCHOSHD (P) 27,519, pp. 35,681-2 n. 6 (No. 80-4109, 1986).[[24]] Collier-Keyworth points out that in cross-examination Hart testified she did notknow the \”strokes per minute\” for the presses and suggests that this casts adoubt on her testimony that she measured the speed of the presses. However, Hart’stestimony that she did not know the \”strokes per minute\” does not contradict herunequivocal testimony that she timed the presses and found that the time between strokeswas less than one second. Under the standard, the noise is deemed continuous if the timebetween strokes is less than one second and, once this is known, it is not necessary todetermine the exact time between strokes or the exact stroke rate.[[25]] The strip chart recordings of noise levels made by Barry and Rockwell show noiselevels in the vicinity of the presses ranging from 95 to 105 dBA. Although thesemeasurements were made on different days than Hart’s, they lend credence to Hart’smeasurements indicating that the sound levels near the presses were typically in thisrange.[[26]] See Table 2 of Field Service Memorandum No. 11, in Appendix B, p. B-36 of the IHTM,note 23 above. Cf. 29 C.F.R. ? 1910.95, Appendix A, Table A-1 (hearing conservationamendment)(entry for 91.9 dBA corresponds to dose of 130 percent).[[27]] The error factors for Type 2 sound level meters are found in ANSI S1.4-1971,\”Specification for Sound Level Meters,\” at 11, Table 3. Some of the informationin that table, including the error factor at 8000 hertz, was included in the papers Dr.Barry presented at Purdue University, which appears in the record as Exhibit R-62. OSHAapplied that information to Type 2 dosimeters in its IHTM. See Table 1 of Field ServiceMemorandum No. 12, in Appendix B, pp. B-44–8-45 of the IHTM, note 23 above.[[28]] Because he vacated all citation items on finding that the standard excluded impulsenoise, Judge Furcolo did not make findings on the merits. Normally, we would remand to himfor such findings. However, in view of the age of the case, we will make our own findings.[[29]] The Secretary did not attempt to show that administrative controls for thesemachines were feasible.[[30]] Barry believed that erecting acoustical enclosures entirely around the presseswould be impractical due to space limitations and production demands.[[31]] The dies for each press were changed an average of about once per day. Some ofCollier- Keyworth’s dies weighed as much as 1,000 pounds and had to be changed using achain hoist. When the chain hoist was used, the die could swing into the enclosure anddamage it. Barry testified that this could be avoided if the operator was careful. Holmertestified, however, that another company experienced severe damage to similar enclosuresafter 14 to 20 die changes. Holmer also estimated that enclosures would add 20 to 40minutes to the time required for a die change.[[32]] The highest dosimeter reading the Secretary obtained for any of the pressoperators was 305%. This is equivalent to an eight-hour time-weighted average exposure of98 dBA. See section 1910.95, Appendix A, Table A-1.[[33]] Most of the studies relied on in the paper were performed with gunshot noise,but the authors considered the information sufficiently general to be extended to othertypes of impulse noise.[[34]] Threshold shift is a measure of hearing loss. A person’s hearing threshold is thelowest sound level in decibels that person can detect. If the person suffers hearing loss,his threshold increases, i.e., he can no longer hear decibel levels as low as hepreviously could. The number of decibels by which his threshold increases is his thresholdshift. A permanent hearing loss is referred to as a permanent threshold shift or PTS.Short exposures to high noise levels can cause a temporary hearing loss, or temporarythreshold shift. When a person suffers a temporary threshold shift, his hearing recoversafter the exposure to high noise levels ceases. However, repeated exposures sufficient tocause temporary threshold shifts can lead to a permanent threshold shift. Therefore, totest whether noise exposures give rise to the possibility of permanent hearing loss,scientists measure temporary threshold shifts in exposed individuals. If an exposureproduces measurable temporary threshold shifts, repetitive exposures of the same magnitudewill eventually cause permanent threshold shifts. See 46 Fed. Reg. 4078, 4080 (1981)(preamble to hearing conservation amendment).”