“SECRETARY OF LABOR,Complainant,v.COLLIER-KEYWORTH COMPANY,Respondent.OSHRC DOCKET NO. 80-2848_ORDER_Before: BUCKLEY, Chairman, and AREY, Commissioner.BY THE COMMISSION:The parties reached a settlement agreement during appeal proceedings inthis case in the United States Court of Appeals for the First Circuit.The court dismissed the appeal in accordance with the joint motion ofthe parties reciting the existence of the settlement agreement.McLaughlin v. Collier-Keyworth Company, No. 88- 2140 (1st Cir., March22, 1989). In its mandate, the court stated:The case is remanded to the Occupational Safety and Health ReviewCommission with instructions to vacate its decisions and orders in thiscase in accordance with the settlement agreement…..In accordance with that mandate, the Commission’s order and decision inthis case are vacated. Part 1 (a) of the citation for violation of 29 C.F. R. ? 1910.95 (a) is affirmed. Parts 1 (b) and 1 (c) of the citationfor violation of 29 C. F. R. ? 1910.95 (b) are vacated. No penalty isassessed.FOR THE COMMISSIONRAY H. DARLING, JR.EXECUTIVE SECRETARYDATED: April 27, 1989————————————————————————SECRETARY OF LABOR,Complainantv.COLLIER-KEYWORTH COMPANYRespondentOSHRC Docket No. 80-2848_THE REMAND_The Review Commission remanded this case to the Administrative Law Judge\”to afford the Secretary an opportunity to rebut officially-noticeddocuments with evidence of the Secretary’s _intent when he adopted thestandard_\” at29 C. F. R. ? 1910.95 a-b in 1969. [Emphasis added]The Administrative Law Judge is directed to propose \”a supplementaldecision affirming, modifying or vacating those citation items relevantto the impulse noise issue in light of any additional evidence that theparties submit.\”Part of the Review Commission’s decision reads as follows: \”…therecord in this case contains evidence of events leading up to theadoption of the Walsh-Healey standard …. The parties presentedwitnesses…who were personally familiar with many of the events leadingup to the standard’s adoption. This testimony is supplemented bydocumentary exhibits introduced by the parties and other documents thatwe officially notice …. The documents we officially notice includeonly Labor Department publications and scientific papers cited indocuments that were introduced into evidence … Our purpose in takingofficial notice is not to determine whether impulse noise is harmful orwhether the pre-ponderance of scientific thinking in 1969 would havefavored the regulation of impulse noise under Table G-16 …. Ourpurpose is instead to determine the intent of the Secretary in 1969 byexamining the body of knowledge on impulse noise that influenced theadoption of the standard. Because our decision rests in part on theseofficially noticed documents, we shall afford the Secretary anopportunity to rebut them with documents and other evidence of _hisintent when he adopted the standard_.\” [Emphasis provided]…ReviewCommission decision, pages 14, 15._History-of-the-Standard_The Technical Committee on Noise of the American Industrial HygieneAssociation [AIHA] suggested a committee of noise experts to recommendguidelines. The Labor Department agreed, and the Inter-Society Committeeon Guidelines for Noise Exposure Control came into being. The so-calledInter-Society Committee had two members from each of five technicalsocieties: the AIHA, the ACGIH [American Conference of GovernmentalIndustrial Hygienists], the American Academy of Ophthalmology andOtolaryngology, the American Academy of Occupational Medicine, and theIndustrial Medical Association. Herbert H. Jones was Chairman of theACGIH and one of the ACGIH representatives was Van Atta who, accordingto Jones, had primary responsibility in the noise area for the LaborDepartment ….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 statedthat its proposed limits would \”not apply to impulse or impact type ofnoise.\”The Review Commission pointed out that \”the criteria proposed by boththe Inter-Society Committee and the ACGIH committee excluded impulsenoise, with the exception of the ACGIH proposal for a peak limit of 140dB for impulse noise…On September 20, 1968, the Labor Department published a proposedstandard to regulate workplace noise exposure. 33 Fed. Reg. 12458,14259-60. This proposed standard bore very little resemblance to thepresent standard… and included impulse noise in its exposure calculations.And on January 17, 1969, the Labor Department issued a Walsh-Healeynoise standard very similar to that which had been proposed andretaining the provision on impulse noise. However, this proposalstandard was stayed by the Secretary of Labor … 34 Fed. Reg. 2207.On May 20, 1969, the Labor department issued a new standard that (in thewords of the Review Commission) \”is identical to the one at issue inthis case. Major differences between the earlier standard and the laterstandard include provisions relevant to the impulse noise issue. Theearlier standard explicitly stated that … impulse noise was to beincluded in weekly exposure calculations. However, the final standardcontained no similar provision and included a provision with nocounterpart in the earlier standard–a recommended limit of 140 dB forimpulse noise.\”The Review Commission concluded that: \”The final standard stronglyresembled that adopted by the ACGI: on May 12, 1969 …\”….. ReviewCommission, 15-21.To summarize the Review Commission’s apparent analysis: On September 20,1968, the Labor Department’s proposed standard included impulse noise inits exposure calculations. And on January 17, 1969, the Labor Departmentproposed a standard that retained the provision on impulse noise, butthe Secretary of Labor stayed it.Then on May 20, 1969, the Labor Department issued a standard that had noprovision including impulse noise in exposure calculations but had arecommended limit of 140 dB for impulse noise.The Review Commission also said: \”Jones was still Chairman of the ACGIHCommittee; he stated that Dr. Van Atta of the Labor Department had beenaware of the wordings of the Committee and of its proposed standard…\”… Review Commission decision 21.As the Review Commission pointed out, the standard must be given thesame meaning it had under the Walsh-Healey Act … Review Commissiondecision 14.The Labor Department’s Bulletin 334 of December 4, 1970, revised on June8, 1971, indicates that the Secretary was aware of the scientificreasons why impulse noise is excluded from the standard… ReviewCommission decision 27. It is also consistent with the ReviewCommission’s finding that the evidence is overwhelming that OSHAinterpreted the standard to exclude impulse noise from Table G -16…Review Commission decision 32._The Remand Transcript_Because the Remand was heard at various dates, the four volumes of theRemand Transcript are herein designated by the roman numerals I, II,III, and IV preceding the page number._Scope of the Remand_In addition to the usual rules of evidence, the testimony andevidentiary exhibits were further restricted by the parameters of theReview Commission’s Remand order: \”….. evidence of the Secretary’sintent when he adopted the standard in 1969.\”_Excluded Evidence_There were several rejected proffers of evidence, However, even if anyor all of such evidence had been admitted, it was not of sufficientweight or credibility to affect any finding or the decision._The Issue_The question on Remand is not whether employees are better protected ifimpulse\/impact noise is included in determining if the limitationsimposed by the table G-16 were exceeded; it is rather to determinewhether the Secretary of Labor intended to have impulse\/impact noiseincluded in table G-16, for whatever reasons_Findings and Conclusions_I have considered the briefs and the Respondent’s 161 proposed findingsof fact and conclusions of law. To the extent shown herein these areadopted; otherwise, they are rejected as not being supported by theevidence or law or as being immaterial or irrelevant or beyond the scopeof the Order of Remand._Testimony at Remand Hearing_Four witnesses testified at the Remand Hearing: Davis, Kamperman, Wardand Hildyard. Part of their testimony is summarized below.[1] _Irving Davis_Davis, a retired industrial hygiene engineer, was involved in samplingemployee exposure to noise in Michigan, and dealt predominantly with theMichigan noise standard (I, p.16,17). He was a member of the Americanconference of Governmental Industrial Hygienists (\”ACGIH\”) since theearly 1950’s and was appointed to the Physical Agents Committee from1967 to the present. Davis was also a member of the American IndustrialHygiene Association in 1969 and 1971. (I, p.19-20)Davis’ testimony revealed that all work places had a mix of steady-stateand impact\/impulse noise (I. p.18, 36) and that the threshold limitvalue included all noise; he stated that impulse\/impact noise should notand could not be practically edited from a noise survey (I, p.36).Further, that the intent of the noise standard proposed by the ACGIHcommittee in 1968 (Review Commission Decision, Appendix, P.57) was thatit did not apply to \”peak\” measurements of impact or impulse noise. Itdid not mean that impact or impulse noises should be edited or excludedfrom the total noise measurement (I, p.27-28). Although Davis agreedthat the qualifying term \”peak\” did not appear in his committee’sdefinition of impulse\/impact and continuous noise \”we understood that tobe ‘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 orfederal OSHA noise standard interpretation, or any documents relating toimpulse noise measurements (I, pp. 78-79).Similarly, Davis was aware of the statement in Bulletin 334 of theDepartment of Labor (R66 of Review Commission Decision) which explained,in part, that \”[i]n contrast with 115 dBA upper limit for steady noise,the higher intensity for impact noise is permissible because noiseimpulse resulting from impact… is passed before the ear has time toreact fully.\” He understood that this was based on available scientificand medical evidence, but that his personal understanding of this wasthat it was intended to apply only to peak sound pressure (I, p.147-148). In contrast, at his deposition, Davis did not limit his answerto \”peak\”, stating that he understood that all impulse\/impact sound didnot reach the inner ear (I, p.148)In R11, a copy of The Physical Agents Committee’s document referring tothe values expressed in the ACGIH TLU, it states that \”[t]hese values… [do] not apply to impact or impulse type of noises.\” Davisunderstood this to mean \”peak\” measurements of impact or impulse noise(I, p.183).Davis was not involved in any Department of Labor meetings concerningthe development of federal OSHA standards (I, p.117-118). He neverdiscussed the noise standard or impulse noise with Van Atta (I, p.119).He did not participate or have personal knowledge of what went in to thepromulgation 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 to1970 that discussed the interpretation of the noise standard and whetherimpact\/impulse noise was or was not required to be included forenforcement purposes, nor did he discuss the subject with OSHA personnel(I, p.137). However, his office received \”CPL’s\” (documents intended toprovide interpretations of Federal OSHA standards) throughout the 1970’s(I, p.173-174).[[2]] _George Kamperman_Kamperman, a consulting engineer in noise control and sound levelmeters, was a member of several American National Standards Institute(ANSI) committees, one of which studied the performance characteristicsand capabilities of sound level meters (I, p.194; II, p.223).The focal point of Kamperman’s testimony involved a June 11 and 12, 1969symposium on industrial noise, which was held to discuss theimplications of the Walsh-Healey Act which had been promulgated in May,1969. (II, p.244).Dr. Floyd Van Atta, from the Department of Labor, was invited to speak,as he was considered the \”architect\” of the noise regulation standard inthe Walsh- Healey Act (II, p.245-246). He discussed the background ofthe new noise standard and how it was to be enforced by the Departmentof Labor (II, p.247). Panel discussions were held and Kamperman engagedin informal discussions with Van Atta at the time (II, p. 247, 263).Kamperman’s basis for testifying to Van Atta’s position with respect toimpulse\/impact noise was founded on four such informal meetings, twotaking place at dinners on the evenings before each day’s symposiummeeting (II, p.248), and two other seminar meetings, the date andlocation of which Kamperman could not recall (II, p.324-325).Throughout his testimony, Kamperman stated what he remembered to be VanAtta’s position (thus, the Department of Labor’s) with respect to theWalsh-Healey noise standard, which he gleaned from informal meetings andVan Atta’s symposium presentation. He recalled that Van Atta believedthat all noise in an industrial environment, including impact\/impulsenoise, was to be in the Table G-16 computation, and that there was anadditional requirement that impact\/impulse noise not exceed 140 dB peaksound pressure (II. p.249,253,262,268,275,278).However, Kamperman had never seen a document or official agencyinterpretation, including OSHA CPL’s for noise standards or noisemeasurement, nor any other written interpretation for the Department ofLabor, or OSHA, instructing employers to include impulse noises in TableG-16 when making noise measurements (II, p.305,354,360,361). Thehandouts at the symposium did not cover impact\/impulse noise or itscomputation under Table G-16 (II, p.295-296). Kamperman could not recallVan Atta’s opening or closing remarks of his speech and could not quoteanything that Van Atta said during the two-day symposium (II, p.318).Kamperman stated that he was not a \”careful note taker\”; he took nonotes 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 Attaabout the source of the Walsh-Healey noise standard (II, p.328), nor washe aware of any of Dr. Van Atta’s writings (II, p.346).Kamperman stated at his deposition that he was \”not capable of recallingthings \” (II, p. 335). He had never worked with Van Atta on a day-to-daybasis (II, p.360).[3] _W. Dixon Ward_Ward, a professor at the University of Minnesota, teaches, consults anddoes research in the field of noise and its effects on humans andanimals (II, p.365). In the 1950’s and 60’s, his research dealt with theeffects of impulse noise (II, p.368). Ward was chairman of the workinggroup of the Committee on Hearing Environmental Acoustics which put outa proposed damage risk criteria for impulse noise in 1968.Ward’s testimony indicated that, as of 1969, there is no sound,scientific basis for excluding the impulse noise component from thetotal worker noise exposure calculation used to protect hearing; bothsteady-state and impact noise are potentially hazardous in an industrialenvironment (II, p. 380, 381, 384, 396),. However, he also noted thatbefore 1971, there were scientific studies that indicated impact\/impulsenoise situations should be treated separately from continuous or steady-state noise (III, p.62). His understanding of the original OSHA noisestandard was that its permissible exposure level for non-impulse noiseat 90 for an eight hour duration is less than or equal to 140 dB peakfor impulse noise regardless of its duration (II, p.448-449). Ward wasnot aware of any documents that interpreted how impact noise was to betreated under the OSHA noise standard (III, p.158-160)Ward had no personal participation or knowledge of the promulgationprocesses, events or discussions that resulted in both the Walsh-Healeyor OSHA noise standards (II, p.370, 448; III, p. 31-33). He was notfamiliar with Dr. Van Atta’s writings until this hearing (II, p.449).Ward had never had discussions with Van Atta concerning impact\/impulsenoise or its measurement under Table G-16 (III, p.46). He was unfamiliarwith the identities of any of the draftsmen for the Walsh-Healey or OSHAnoise standards (III, p.33).[4]_Victor Hildyard_Hildyard, a physician and surgeon and specialist in otology, hadencountered the effects of impact\/impulse noise in clinical practice. Hewas appointed by Undersecretary of Labor Guenther to be chairman of theOSHA Standards Advisory committee in 1972 (III, p.196). Thefifteen-person committee, which met in 1973, in meetings open to thepublic, reviewed and evaluated noise standards relating to permissiblelevels of exposure, reviewed the history of the criteria documents thatled up to the original noise standard of OSHA and Walsh-Healey,collected information on new research and development performed sincethe original standard and made recommendations to the Secretary of Laborfor a revised noise standard (III, p.196, 218, 219). Dr. Van Atta, as arepresentative of the Department of Labor, was an advisor to thecommittee (III, p. 196), and as such, outlined the course and objectivesof the group, and assisted in tracing the history of the standards (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). Van Atta was present, as advisor, at every committeemeeting (III, p.230).Hildyard had numerous private discussions with Dr. Van Atta in 1973concerning the inclusion or exclusion of impulse noise from Table G-16(IV, p.232, 280). At the time, Dr. Van Atta expressed the Department ofLabor’s position with respect to permissible noise level exposure forcontinuous 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 noise could not be included in Table G-16, asimpact\/impulse noise and continuous noise were to be measured separatelyand had distinct damage risk criteria; impulse noise could not beintegrated into the Table, or the threshold limit values, or thepermissible noise values for continuous noise (IV, p.235-236, 280, 281,283). In addition, the departmental position, according to Van Atta, andbased on ACGIH conclusions and studies, was that the human ear treatsthese two types of noises differently (IV, p. 235, 237-239). Dr. VanAtta stated that the Department of Labor’s position was that if a workerstayed within the permissible limits of 140 dB peak for impulse noise,for a working day over a working lifetime, his hearing would not be inany danger (IV, p.239- 240). Hildyard testified that Van Atta statedthat, in 1969, the Department of Labor intended to treat impulse noisedifferently from continuous noise, as he used the Walsh- Healey standardas a starting point for the Committee to continue its work(IV, p. 237, 255, 282). Van Atta’s position in 1973 was the same as itwas in 1969 (IV, p. 282)._The Secretary of Labor’s representative_All the facts, and the inferences to be drawn from them, indicated quiteclearly that the Secretary of Labor was represented by Van Atta, a LaborDepartment employee who participated in proceedings pertaining to thenoise standard in question. In fact, the Complainant stipulated that VanAtta was (in 1973):\”…. an employee of the Department of Labor and hewas at this committee meeting in his official capacity…\” … Tr. IV251. And both sides, at one time or another, took the position that VanAtta represented the Secretary of Labor in matters pertaining to thenoise standard._Discussion_An analysis of the testimony of each of the four witnesses who testifiedon remand [Davis, Kamperman, Ward, and Hildyard] makes it clear that thedecision on remand must be largely based on a choice of relying oneither the memory of Kamperman or that of Hildyard. That is because thebest evidence of the intent of the Secretary of Labor–the stated aim ofthe hearing on remand–would be best disclosed by the conduct andstatements of the Secretary’s representative (van Atta). Of the four,only Kamperman and Hildyard gave specific instances of such conduct andstatements by van Atta. Should one be relied on more than the other?I find that both Kamperman and Hildyard were extremely well qualified intheir fields of expertise; and I find that both were equally candid andhonest in their testimony.I find that both have tried equally hard to recall events that happenedmany years before the hearing. However, I find that the memory ofHildyard was more likely to recall specific details of conduct andstatements by van Atta because, as Chairman of the Committee to whichvan Atta was advisor, Hildyard would in all probability have had morecommunications with van Atta, and more reason to pay attention to vanAtta’s statements and conduct, than Kamperman or other committeemembers. For primarily that circumstance, I find that the memory ofHildyard is to be relied on more than anyone else’s when [as here] it isa question of great concern to the committee he chaired.I find that, when the standard in question was adopted in 1969, it wasthe Secretary of Labor’s intent that impact\/impulse noise should not beincluded in table G-16.Accordingly, as the Review Commission said in its decision of April 6,1987, which is followed and affirmed by the undersigned: \”….. wevacate citations item 1a (B) and (D), and ib (b) and (D) …… Wevacate 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 concernedwith justice and due process of law should tolerate a potentialsituation where neither the Complainant nor the Respondent can bereasonably certain of exactly what a standard mandates. The meaning ofits words should not have to be determined by implication orinterpretation or speculation or guesswork.And certainly a standard should not be so worded that it possibly couldcall for the use of tools or implements or testing methods thatnecessarily result in erroneous measurements or conclusions.Unfortunately, the standard here is subject to such flaws.The Labor Department is strongly urged to take the necessary steps tohave the standard be amended or re-worded so that its meaning is crystalclear to all who may be concerned in its enforcement.FOSTER FURCOLOJudge, OSHRCDated: August 24, 1988Boston, Massachusetts————————————————————————SECRETARY OF LABOR,Complainant,v.COLLIER-KEYWORTH COMPANY,Respondent.OSHRC Docket No. 80- 2848_ORDER OF REMAND_On April 6, 1987, the Commission issued a decision holding that TableG-16 of the occupational noise standard at 29 C. F. R. ? 1910.95 (a)-(b)did not cover impulse noise. The Commission based its holding on thelanguage of the standard, its legislative history and the Secretary’sinterpretation of the standard shortly after its adoption. In weighingthe legislative history of the standard and the Secretary’sinterpretation of the standard shortly after its adoption, we referredto documents that we officially noticed under section 7 (d) of theAdministrative Procedure Act, 5 U. S. C. ? 556 (e). We also stated thatwe would afford the Secretary the opportunity to rebut theofficially-noticed documents with documents and other evidence of hisintent when he adopted the standard in 1969. The Commission thereforeordered that certain citation items be vacated unless the Secretaryrequested an opportunity within 15 days to rebut officially-noticeddocuments.The Secretary has filed a motion for an extension of time to gather,review and possibly submit documents relevant to the intent of thestandard’s drafters with respect to the coverage of impulse noise. TheSecretary asks for extension of three weeks, through May 11, 1987.Ordinarily, we would simply grant this motion, for it is supported bygood cause. In this case, however, the Secretary’s motion would, ifgranted, cause the period of time to extend beyond the term of one ofthe Commission’s two current members. The Commission might for some timetherefore be unable to directly act on further motions in the case andmight be unable to remand the matter to the administrative law judge toreceive further documents and supporting testimony. Inasmuch as thisissue is an important one and should be expeditiously resolved, we willgrant the motion and remand this case to the administrative law judgenow with instructions to afford the Secretary an opportunity to rebutofficially-noticed documents with evidence of the Secretary’s intentwhen he adopted the standard in 1969. The judge shall expeditiouslyprepare supplemental decision affirming, modifying or vacating thosecitation items relevant to the impulse noise issue in light of anyadditional evidence that the parties submit. If the Secretary does notdesire that the record be re-opened, the judge shall issue a decisionvacating the citation items in accordance with our decision of April 6,1987.Accordingly, this case is remanded to the administrative law judge forfurther proceedings.FOR THE COMMISSIONRay H. Darling, Jr.Executive SecretaryDATED: April 22, 1987————————————————————————SECRETARY OF LABOR,Complainant,v.COLLIER-KEYWORTH COMPANY,Respondent.OSHRC Docket No. 80-2848_DECISION_Before: BUCKLEY, Chairman; WALL, Commissioner.BY THE COMMISSION:This case is before the Occupational Safety and Health Review Commissionunder 29 U. S. C. ? 661 (j), section 12 (j) of the Occupational Safetyand Health Act of 1970, 29 U. S. C. ?? 651- 678 (\”the Act\” or \”the OSHAct\”). The Commission is an adjudicatory agency, independent of theDepartment of Labor and the Occupational Safety and HealthAdministration (\”OSHA\”) It was established to resolve disputes arisingout of enforcement actions brought by the Secretary of Labor under theAct and has no regulatory functions. _See _section 10 (c) of the Act, 29U. S. C. ? 659 (c).I _Introduction_Collier-Keyworth Company manufacturers swivel and tilt mechanisms foroffice chairs in a plant in Gardner, Massachusetts. In April 1980, OSHAindustrial hygienists inspected Collier- Keyworth’s plant to determinewhether the company was in compliance with the occupational noisestandard at 29 C. F. R. ? 1910.95 (a)-(b). From measurements made duringthe inspection, OSHA concluded that employees who operated power pressesand lathes at the plant were exposed to noise in excess of the limitsestablished by the standard. It therefore cited Collier-Keyworth forvarious violations of section 1910.95. At the time of the allegedviolations, the standard provided:[[1]]? 1910.95 _Occupational noise exposure._(a) Protection against the effects of noise exposure shall be providedwhen the sound levels exceed those shown in Table G-16 when measured onthe A scale of a standard sound level meter at slow response.(b) (1) When employees are subjected to sound exceeding those listed inTable G-16, feasible administrative or engineering controls shall beutilized. If such controls fail to reduce sound levels within the levelsof Table G-16, personal protective equipment shall be provided and usedto reduce sound levels within the levels of the table.(2) If the variations in noise level involve maxima at intervals of 1second 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 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 periodsof noise exposure of different levels, their combined effect should beconsidered, rather than the individual effect of each. If the sum of thefollowing fractions: C1\/T1 + C2\/T2) [+………] Cn\/Tn exceeds unity,then, the mixed exposure should be considered to exceed the 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 peaksound pressure level.The principal dispute in this case is whether Table G-16 regulates akind of noise called \”impulse noise.\” The dispute arises in this casebecause, in determining whether Collier-Keyworth’s employees wereexposed to more noise than Table G-16 permits, OSHA employed measuringdevices-sound level meters and personal noise dosimeters–thatregistered impulse noises in Collier- Keyworth’s plant. Collier-Keyworthargues that Table G-16 was not intended to regulate impulse noise andtherefore that OSHA’s measurements were unreliable.A. _Measuring Noise Exposure Under Table G-16_Before we set out and discuss these arguments, we shall discussgenerally the two methods of proving that an employer has violated thelimits for noise exposure in Table G-16 of section 1910.95 (a)-(b).First, the Secretary may show that an employee is subjected to a soundlevel equal to or greater than a level listed in Table G-16 for a longerperiod of time than the table permits. For example, the Secretary couldmeet his burden of proof by showing that an employee is exposed to 92dBA or higher for more than six hours, or to 105 dBA higher for morethan one hour. If this method is used, however, sound levels that lastfor less than their permissible periods would have to be disregarded.Yet, sound levels in industrial plants often fluctuate and continue forless than their permissible periods; some last for only a few minutes orseconds. This method therefore can result in a substantial underestimateof an employee’s total noise exposure.[[2]]The second way in which the Secretary can show overexposure overcomesthis difficulty but introduces others. The second method uses thecumulation formula in the footnote to Table G-16. This formula explainshow one may calculate an employee’s noise dosage when sound levels varythroughout the workday. Under the cumulation formula, a fraction, Cn\/Tn(Cn being the time the employee is exposed to that level and Tn beingthe exposure time permitted at that level), is calculated for eachdifferent noise level to which an employee is exposed during theworkday. At the end of the day, all the fractions thus calculated areadded together. If the total is more than one (\”unity\”), the employeehas been exposed to noise exceeding permitted limits.The cumulation formula yields a more accurave determination of anemployee’s total noise exposure, for it counts as part of the employee’snoise exposure sound levels that continued for less than the permissibleperiod. This permits each variation in noise level to be given itsproper weight and to be cumulated. However, the cumulation formula isconsiderably more difficult to apply. An OSHA compliance officer musthold the microphone of a sound-level meter in an employee’s hearingzone; read each different sound level registered on the meter; with awatch, determine the duration of that level; and record on a notepadeach sound level and its duration. Where the noise level is constantlyvarying, however, it is extremely difficult to manually make the manymeasurements and calculations necessary to apply the formula. And,because the task is so difficult to perform accurately, complianceofficers cannot survey the exposure of more than a few employees in a day.To overcome these problems, the personal noise dosimeter was developed.The dosimeter is an electronic instrument that contains the circuitry ofa standard sound level meter along with other circuitry. A dosimeter issmall enough to be worn by an employee throughout the workday as he goesabout his duties. The dosimeter microphone, which is part of thedosimeter’s sound level meter, is placed in the employee’s hearing zone,where it continually detects the noise to which the employee is subject.The sound level meter circuitry within the dosimeter measures thevarying sound levels and sends that information to the other dosimetercircuitry, which automatically calculates and sums the fraction asrequired by the cumulation formula.[[3]] At the end of the workday, thedosimeter gives a reading in terms of the percentage of the permitteddaily dosage a dosimeter reading of 100 percent means that the sum ofthe fractions is one. A dosimeter reading exceeding 100 percent thusmeans that the permitted daily noise dosage has been exceeded. _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’semployees using dosimeters. Because the dosimeters indicated thatCollier-Keyworth’s power press and lathe operators were exposed to morethan 100 percent of the permitted daily dosage. The Secretary allegesthat the employees were exposed to noise exceeding the limits permittedby the standard. Collier-Keyworth contends that the dosimeter readingscannot be relied upon to find overexposure. The company raises a numberof potential inaccuracies with dosimeters, but its principal argument isthat the dosimeter readings obtained by the Secretary were unreliablebecause some of the noise they measured was impulse noise, a type ofnoise the company argues is not intended to be included in dosagecalculations under Table G-16.B._Impulse Noise_Impulse noise is noise of brief duration produced by a short-livedphysical phenomenon, such as a gunshot, a clap of thunder, or a powerpress stroke. When such noise arises from the impact of two objects, itis called impact noise. The distinction between impact noise and otherimpulse noise is not important to the issues before us. A provision ofthe standard, however, requires that we distinguish between impulsenoises based on the time between their peaks or maxima. Subsection1910.95 (b) (2) states that \”[i]f the variations in noise level involvemaxima at intervals of 1 second or less, it is to be consideredcontinuous\”. This provision reflects that much industrial noise consistsof level of repetitive impulses and that the impulses are often spacedso closely together as to sound continuous. One witness gave the exampleof a gearbox, in which noise originates as the impact of gear teeth ongear teeth but the impacts occur so frequently that the ear does nothear the individual impacts. Subsection (b) (2) provides a criterion forclassifying closely-spaced impulse noise as continuous noise.Concomitantly, expert witnesses for both parties testified that noise isconsidered to be \”impulse noise\” if it involves maxima that are lessthan one second in duration and more than one second apart.Collier-Keyworth’s arguments focus both on the words of the standard andits background. Collier-Keyworth points to a provision that is nowprinted as the second paragraph of the footnote to Table G-16. Thatprovision states that \”[e]xposure to impulsive or impact noise shouldnot exceed 140 dB peak sound pressure level.\” Collier-Keyworth arguesthat this provision demonstrates that the standard treats impulse noisedifferently from other noise. It also points to subsection (b) (2) ofthe standard. Because the one second interval mentioned in thatsubsection corresponds to the interval that is universally recognized asthe dividing line between impulse noise and continuous noise. Thecompany contends that this represents the standard’s intent to draw aline between impulse noise and continuous noise, with the latterregulated by Table G-16 calculation and the former excluded. It alsorelies on various documents and testimony to support its argument that,when the noise standard was adopted, the Secretary did not intend toregulate impulse noise under Table G-16.Administrative Law Judge Foster Furcolo agreed with Collier-Keyworth’sargument that Table G-16 was not intended to cover impulse noise. Onthat basis, the judge vacated the citations in their entirety. We agreewith the judge’s conclusion that impulse noise must be excluded whendetermining whether Table G-16 limits have been exceeded. We furtherfind that the employees covered by items 1a(B) and 1b(B) and (D), of thecitation were exposed to considerable amounts of impulse noise, and asto those employees the Secretary did not prove overexposure tocontinuous noise. Employees covered by citation items 1a (A) and (C),and 1b (A) and (C), however, were exposed to noise defined as continuousby subsection (b) (2) of the standard, i.e., to noise with impulsesoccurring more frequently than once per second. Although we find thatthe Secretary proved that those employees were exposed to noiseexceeding permitted limits, we also find that the Secretary did not showthat Collier-Keyworth failed to take the steps required by the standardto protect the employees. We therefore affirm the judge’s dispositionvacating all citation items.II. _Does Table G-16 Cover Impulse Noise?_The record establishes, as we shall discuss more fully later, that atleast some of the noise measured during OSHA’s inspection ofCollier-Keyworth’s plant was impulse noise, that is, noise with sharpenergy peaks lasting less than one second and spaced more than onesecond apart. If Table G-16 does not regulate impulse noise-or, stateddifferently, if impulse noise must be excluded from the calculation ofdosage when one uses the cumulation formula in Table G-16–thendosimeter readings that include impulse noises produce readings that aretoo high. Therefore, in determining whether the readings obtained byOSHA show that Collier-Keyworth’s employees were exposed to excessivenoise, we must first address Collier-Keyworth’s argument that section1910.95 (a)-(b) does not intend for impulse noise to be included indosage calculations employing Table G-16 limits. [[4]]A. _The Scope of Our Inquiry_The Secretary contends that Collier-Keyworth’s argument should berejected because the record compiled in this litigation \”containssubstantial expert testimony that impulsive …….. noise is no lessdamaging to hearing than continuous noise.\” The Secretary cites thetestimony of several witnesses, including that of a physicianspecializing in otolaryngology, and argues that the degree of permanenthearing loss is directly proportional to the amount of acoustic energytransferred to the ear.[[5]] The Secretary reasons that because theenergy associated with prolonged exposure to impulse noise can causeirreversible hearing loss, it should be regulated by Table G-16.We do not dispute that there is now reason to believe that impulse noisecan cause hearing loss. But in the absence of an OSHA standard, we donot have the authority to regulate exposure to impulse noise. Newmedical and scientific. evidence is not relevant if, as Collier-Keyworthclaims, the Secretary did not intend Table G-16 to cover impulse noisewhen he adopted it. As an adjudicative body, the Commission must takethe standard as it finds it and apply the standard in accordance withthe Secretary’s intent at the time of promulgation. See Oscar Mayer &Co. v. Evan, 441 U. S. 750, 758 (1979) (intent of Congress that enactedstatute is controlling). The Commission has no authority to \”update\” anystandard through interpretation according to the latest scientificfindings. Such legislative authority resides in the Secretary, who, inrulemaking, may consider whether new findings about physical agents makeregulation necessary and what new duties should therefore be imposed onemployers. For the Commission to interpret a standard to produce what itbelieves will be greater protection for employees than the Secretaryoriginally intended both usurps the Secretary’s rulemaking authority anddetracts from the statutory right of those affected by a rule toparticipate in the rulemaking process.B. _The Language of Section 1910.95 (a)-(b)_The Secretary argues that the plain language of the standard indicatesthat he intended to regulate impulse noise under Table G-16. He notesthat section 1910.95 (a) requires protection whenever \”sound levels\”exceed Table G-16 values, and argues that the all-inclusive phrase\”sound levels\” draws no distinction between impulse noise andnon-impulse noise.Standards must, however, be read as a coherent whole, andCollier-Keyworth points to two provisions it contends indicate an intentto exclude impulse noise from Table G-16.Collie-Keyworth points to the statement, now printed as the secondparagraph of the footnote to Table G-16, stating that exposure to peaksound pressure levels of impulse noise should be limited to 140 dB. Itargues that this special provision for impulse noise shows an intent totreat impulse noise differently from other noise. The Secretary, on theother hand, contends that this provision demonstrates that where thestandard intended to distinguish impulse noise from other noise, it didso explicitly.We think that there is force in Collier-Keyworth’s argument. AlthoughTable G-16 sets a ceiling of 115 dBA on sound pressure levels regardlessof the duration of exposure, Wheeling-Pittsburgh Steel Corp., 83 OSAHRC16\/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 warns againstimpulse noise that exceeds 140 dB. This provision would be superfluousif, as the Secretary argues, the all-inclusive phrase \”sound levels\” insection 1910.95 (a) means that all sound, both impulse and non-impulse,must stay within the limits in Table G-16. Thus, the impulse noiseprovision suggests that the \”sound levels\” regulated by Table G-16 donot include all sound levels and that impulse noise must be excludedfrom calculations under Table G-16.[[6]]It might seem somewhat odd that an answer to this important questionmight be suggested by a brief second paragraph of a footnote to a table.However, the drafters of the standard did not intend the impulse noiseprovision to be relegated to such an obscure position. The provision wasoriginally placed in the next of the standard but later became locatedin the footnote as the result of a printer’s error.[[7]] We thereforeascribe no importance to the placement of the impulse noise provision.The second provision on which Collier-Keyworth relies is subsection(b)(2), which defines noise as continuous if the peaks are closer thanone second apart. Collier-Keyworth contends that the Secretary’sclassification of closely-spaced impulses as continuous noise must beviewed as evidence of an intent to distinguish impulse noise fromcontinuous noise and to exclude impulse noise from the criteriaestablished for continuous noise. The Secretary’s brief does not addresssubsection (b)(2) or suggest how it could be reconciled with hisposition that impulse noise is subject to the limits of Table G-16.We agree with Collier-Keyworth that subsection (b)(2) appears torepresent an attempt to distinguish impulse noise from continuous noise.Both parties agree that continuous noise, i.e., noise of constantintensity, is included in Table G-16 calculations. By defining noisewith peaks closer than one second apart as continuous, subsection (b)(2)obviously means that such noise is to be included in dosagecalculations. A provision that says something is included, however,implies that something else is excluded, for there would otherwise be noreason for the provision. As the one-second criterion in subsection(b)(2) represents the distinction between impulse noise and non-impulsenoise, the section suggests that the drafters of the standard intendedto exclude impulse noise from Table G-16.On balance, both the 140 dB peak limit for impulse noise and subsection(b)(2) suggest that impulse noise is excluded from dosage calculationsunder Table G-16. Nevertheless, the standard is not entirely clear onits face. It does not expressly exclude impulse noise from Table G- 16.As the Secretary points out, the standard uses the broad term \”soundlevels.\” In light of the ambiguity, we look to evidence extrinsic to thestandard to determine whether the drafters intended to exclude impulsenoise from such calculations.C. _Legislative History of the Standard_Section 1910.95 is derived from 41 C.F.R. ? 50-204.10, a standard thatwas originally promulgated in 1969 by the Labor Department’s Bureau ofLabor Standards to regulate work by government contractors under theWalsh-Healey Government Contracts Act, 41 U.S.C. ? 35-45. Section1910.99 (listing sources of standards); see generally American Can Co.,82 OSAHRC 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 ofstandard). Because 41 C.F.R. ? 50.204.10 qualified an \”establishedfederal standard\” under section 3(10) of the Occupational Safety andHealth Act of 1970 (\”the OSH Act\”), the Secretary of Labor wasauthorized to adopt it as an OSHA standard without further rulemakingproceedings. Section 6(a) of the OSH Act, 29 U.S.C. ? 655(a). TheSecretary did so on May 29, 1971, adopting 41 C.F.R. ? 50-204.10verbatim as an OSHA standard and codifying it at 29 C.F.R.? 1910.95. 36Fed. Reg. 10466, 10513. Because the Secretary did not, and–withexceptions not pertinent here–could not substantively amend thestandard when he summarily adopted it as an OSHA standard, we must givethe standard the same meaning it had under the Walsh-Healey Act. SeeAmerican Can, 10 BNA OSHC at 1310-11, 1982 CCH OSHD at pp. 32,413-14;Sherwin-Williams Co., 84 OSAHRC 28\/A2, 11 BNA OSHC 2105, 2109-10,1984-85 CCH OSHD (P) 26,986, pp. 34,701-02 (No. 14131, 1984).The promulgation of 41 C.F.R.? 50-204.10 represented the culmination ofa long effort by the Labor Department and other organizations to developexposure limits for noise that would protect workers againstnoise-induced hearing loss. Although the preamble that accompanied thestandard when it was adopted under the Walsh-Healey Act sheds no lighton the impulse noise question, the record in this case contains evidenceof events leading up to the adoption of the Walsh- Healey standard, aswell as evidence of the Secretary’s interpretation of the standardshortly after its promulgation. The parties presented witnesses, JamesH. Botsford and Herbert H. Jones, who were personally familiar with manyof the events leading up to the standard’s adoption. Their testimony issupplemented by documentary exhibits introduced by the parties and otherdocuments that we officially notice under section 7(d) of theAdministrative Procedure Act, 5 U.S.C. ? 556(e).[[8]] Our examination ofthe record and the material that we officially notice, together with thewords of the standard, lead us to conclude that the Secretary did notintend for Table G-16 to regulate impulse noise when the standard waspromulgated.The documents we officially notice include only Labor Departmentpublications and scientific papers cited in documents that wereintroduced into evidence. Our purpose in taking official notice is notto determine whether impulse noise is harmful or whether thepreponderance of scientific thinking in 1969 would have favored theregulation of impulse noise under Table G-16. As we have said, weighingsuch evidence is not our function but the Secretary’s. Our purpose isinstead to determine the intent of the Secretary in 1969 by examiningthe body of knowledge on impulse noise that influenced the adoption ofthe standard. Because our decision rests in part on theseofficially-noted documents, we shall afford the Secretary an opportunityto rebut them with documents and other evidence of his intent when headopted the standard.In 1960, the Walsh-Healey standard for noise stated in its entirety:\”Noise shall be reasonably reduced or eliminated as a means ofpreventing fatigue or accidents.\” 25 Fed. Reg. 13809, 13825 (1960). Inearly 1964, the department proposed numerical guidelines that wouldestablish weekly exposure limits for \”continuous steady noise\” and alsoestablish a peak limit of 135 dB for \”any exposure….however short induration other than impact noises. . . . \” U.S Dept. of Labor, Bureau ofLabor Standards, \”Suggested Language for a Noise Control Program,\” asprinted in \”Noise: Guidelines for control issued by Bureau of LaborStandards,\” Safety Standards 18, 20-21, 24 (U.S. Dept. of Labor,March-April 1964 ; see also U.S. Dept. of Labor, Bureau of LaborStandards, Suggest Language for a Noise Control Program (1965).The Technical Committee on Noise of the American Industrial HygieneAssociation (\”AIHA\”) met in May 1964 with Jones (then of the U.S.Department of Health, Education and Welfare) and Botsford (then employedby Bethlehem Steel, its senior noise control engineer). The committeemembers believed that the newly-published guidelines had technicalerrors in them and that better guidelines could be developed. The AIHAtherefore decided to offer to the Labor Department the formation of acommittee of noise experts to recommend different guidelines. The LaborDepartment agreed to the formation of such a committee, which was calledthe Inter-Society Committee on Guidelines for Noise Exposure Control(\”Inter-Society Committee\”). The committee consisted of two members fromeach of five technical societies: the AIHA, the American Conference ofGovernmental Industrial Hygienists (\”ACGIH\”), the American Academy ofOphthalmology and Otolaryngology, the American Academy of OccupationalMedicine, and the Industrial Medical Association. One of the ACGIHrepresentatives was Dr. Floyd Van Atta of the Labor Department, who,according to Jones, \”had primary responsibility in the noise area as faras the Department of Labor was concerned.\”The Inter-Society Committee issued a report in 1967, which itcharacterized as the \”first attempt to extract and condense pertinentdata from various scientific literature into a meaningful andauthoritative guide.\” Inter-Society Committee, \”Guidelines for NoiseExposure Control,\” 28 Am. Indus. Hygiene J. 418, 419-22 (Sept.-Oct.1967)(I-S). For this inquiry, it is noteworthy that the committee’sguidelines were directed at developing exposure criteria for only\”steady\” noise. [[9]] The following are excerpts from the guidelines:I. _Foreward_Noise-induced hearing loss increases with both the intensity of thenoise and the duration of exposure. Generally, many years of exposure tohigh noise levels are required to produce significant permanentimpairment in the exposed group; however, there will be markeddifferences in the hearing of individuals and in their response tonoise. . . . These Guidelines will be directed toward the prevention ofthat portion of the permanent hearing loss resulting from exposure tosteady noise.III. _Occupational Hearing Loss Control Program_A. _Evaluation of the Noise Hazard_1. _Noise Measurement._Continuous or intermittent steady noise is readily measured by standardinstruments; impulsive noise requires special procedures not consideredhere. [Footnote omitted.]2._Hazard Rating._(a) Continuous Exposure. . . . The first two columns of Table 1.[omitted] indicate the steady noise levels to which the various groups[of persons with hearing loss] were exposed . . . .(b) Intermittent and Part-time Exposure. The studies on which Table Iand Figure I [omitted] are based, dealt with men exposed to noise duringa normal workday, of eight hours’ duration. . .The report went on to explain that, although there were no long-termstudies of the effects of intermittent exposures, the results of somestudies implied the \”simple rule\”that for each halving of daily exposure time, the noise levels may beincreased by 5 db up to a maximum of 115 dB . . . without increasing thehazard of hearing impairment.The application of this rule is illustrated in the following table:Permissible Increase in dbfor Less than Eight Hours ExposureDaily Exposure Time(Hours) \tPermissible IncreaseAbove Eight-HourCriterion(Decibels)8 \t04 \t52 \t101 \t151 1\/2 \t201\/4 \t25Notably, the Inter-Society Committee’s report did not propose anyparticular permissible exposure level; for this reason, the AIHA Boardfound the report unacceptable and suggested that the Inter-SocietyCommittee be disbanded. Shortly thereafter, the ACGIH established itsown committee to develop a permissible exposure limit for noise as wellas other physical agents. Jones was chairman of this committee. TheACGIH Committee drafted a proposed standard that was published forpublic comment and accompanied by an explanatory article written byJones, \”ACGIH’s Proposed Threshold Limit Value for Noise,\” 29 Am. Indus.Hygiene J. 537-40 (Nov.-Dec. 1968)(ACGIH). See generally Appendix A.1 tothis decision.The most noteworthy aspect of the ACGIH Committee’s proposal is that ittwice stated that its proposed limits would \”not apply to impulse orimpact type of noise.\” ACGIH at 540 (proposed standard). Instead, theproposed standard stated, \”[i]t is recommended that exposure to thistype of noise should not exceed 140 dB peak sound pressure 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 thepresent time it appears desirable to establish a limit of 92 dBA for 4to 8 hours of exposure per day to broad band continuous noise . . .Laboratory data . . . and . . . field data indicate that, when exposureis for less than a full 8-hour period or is intermittent in nature, theear can tolerate more acoustical energy per day than for a singleexposure to continuous noise. Considering these two factors, the limitis increased 5 decibels for each halving of exposure time. The exposuretime is the summation of the exposure periods for the work dayregardless of whether this is a single exposure or an exposure which isintermittent in nature.Very little data is available upon which to base exposure to impact orimpulsive noise. It is known that exposure to a small number of 140 dBimpulsive noises of short duration will produce a temporary thresholdshift. Until additional data is available, a limit of 140 dB is beingset for impact or impulsive noise.ACGIH at 538 (article)(references omitted).Thus, the criteria proposed by both the Inter-Society Committee and theACGIH Committee excluded impulse noise, with the exception of the ACGIHproposal for a peak limit of 140 dB for impulse noise. The reason theyotherwise excluded impulse noise was apparently because, as stated inJones’ article, \”[v]ery little data is available upon which to baseexposure to impact or impulsive noise.\” Both the Inter-Society Committeeand the ACGIH Committee had cited a number of scientific studiescompleted by the late 1960’s that attempted to measure the effect ofnoise on human hearing. These studies, which are excerpted in theappendix to this decision, had measured hearing loss caused by variousdegrees of noise exposure. Because most of them involved purelysteady-state noise, they formed a substantial body of evidence fromwhich permissible exposure limits and an exchange rate–the number ofdecibels by which sound levels could rise if exposure time washalved–could be derived. However, there was considerably less evidenceon which to base permissible exposure limits to impulse noise. Thescientists who attempted to develop hearing protection criteriacautioned against applying them to impulse noise, and tended to regardimpulse noise and continuous noise as two distinct problems. The studiescited by the Inter-Society Committee and the ACGIH Committee dealingwith \”steady\” noise primarily attempted to determine a safe eight-hourexposure level and an exchange rate that represented an appropriatetrade-off of higher intensity for a shorter time. Studies of the harmfuleffects of impulse noise, by contrast looked for hearing protectioncriteria in terms of factors such as the peak intensity, total number ofimpulses, and duration of impulses. Thus, the criteria proposed for\”steady\” noise cautioned against application to impulse while criteriafor impulse noise would not, by their very nature, apply to steadynoise. See generally Appendix A.2 – A.7.[[10]]On September 20, 1968, the Labor Department published a proposedstandard to regulate workplace noise exposure. 33 Fed. Reg. 12458,14259-60. This proposed standard bore very little resemblance to thepresent standard. It basically established a weekly average exposurelimit of 85 dB for \”steady (or equivalent) noise\” and included impulsenoise in its exposure calculations. It spoke of noise with \”intervals .. . more than one second and . . . maxima less than 1 second each,\”which fits the definition of impulse noise. The proposed standardprovided that such noise maxima are to be included in the exposurecalculations as if they had durations of 1 second each. See generallyAppendix A.B.The proposal was unfavorably received in the industrial hygienecommunity. Despite this, on January 17, 1969, a few days beforePresident Johnson’s term expired, the Labor Department issued a packageof Walsh-Healey standards, including a noise standard very similar tothat which had been proposed. 34 Fed. Reg. 788, 790-91. The promulgatedstandard retained the exposure limit of the proposed standard and theprovision that dealt with impulse noise.Before the promulgated standard became effective, it was stayed by thenew Secretary of Labor. 34 Fed. Reg. 2207 (1969). On May 20, 1969, theLabor Department issued a new noise standard that differed radicallyfrom the earlier one. 34 Fed. Reg. 7946, 7948-49. Except for somesubsequent corrections (35 Fed. Reg. 1015 (1970)) , the new standard isidentical to the one at issue in this case . Major differences betweenthe earlier standard and the later standard include provisions relevantto the impulse noise issue. The earlier standard explicitly stated thatnoise with maxima less than one second in duration and greater than onesecond apart, i.e., impulse noise, was to be included in weekly exposurecalculations. However, the final standard contained no similar provisionand included a provision with no counterpart in the earlier standard– arecommended limit of 140 dB for impulse noise.The final standard strongly resembled that adopted by the ACGIH on May12, 1969, eight days before the final version of the Walsh-Healeystandard was adopted.[[11]] Jones was still the chairman of the ACGIHCommittee; he stated that Dr. Van Atta of the Labor Department had beenaware of the workings of the Committee and of its proposed standard, andthat he had received advance copies of the final ACGIH standard.Relevant excerpts from the ACGIH standard follow:_Threshold Limit Values Noise__Continuous or intermittent_The sound level shall be determined by a sound level meter . . .operating on the A-weighting network with slow meter response. Exposureshall not exceed that shown in Table 1Table 1Permissible ExposuresDuration per DayHours \tSound leveldB(A)8 \t9066 \t92t4 \t953 \t972 \t1001 1\/2 \t1021 \t1053\/4 \t1071\/2 \t1101\/4 \t115-C**11ACGIH, \”Threshold Limit Values of Physical Agents\” (1969), reprintedin Fundamentals of Industrial Hygiene, Appendix A*Sound level in decibels as measured on a standard level meter operatingon the A-weighting network with slow meter response.**Ceiling Value___________________________These values apply to total time of exposure per working day regardlessof whether this is one continuous exposure or a number of short-termexposures but do not apply to impact or impulse type of noises.When the daily noise exposure is composed of two or more periods ofnoise exposure of different levels, their combined effect should beconsidered, rather than the individual effect of each. If the sum of thefollowing fractions:C1\/T1 + C2\/T2 + ……. Cn\/Tnexceeds unity, then, the mixed exposure should be considered to exceedthe threshold limit value, C1 indicates the total time of exposure at aspecified noise level, and T1 indicates the total time of exposurepermitted at that level . . ._Impulsive or impact noise_It is recommended that exposure to impulsive or impact noise should notexceed 140 decibels peak sound pressure level-CThis ACGIH standard is very similar to the Walsh-Healey standardultimately promulgated by the Secretary of Labor. Indeed, the finalWalsh-Healey standard was much closer to the ACGIH standard than it wasto the earlier Walsh-Healey standard that is supplanted. In particular,the most important part of the final Walsh-Healey standard, the tablelisting the permissible exposure limits, almost identical to thecorresponding table in the ACGIH standard. The passages on impulse noiseand the cumulation formula are also nearly identical to those in theACGIH standard. In light of the similarities between the two finalstandards, and of Jones’ testimony that Dr. Van Atta of the LaborDepartment was familiar with the proceedings of the ACGIH Committee andhad advance copies of its work products, we infer–as do both theSecretary and Collier-Keyworth–that the final ACGIH standard heavilyinfluenced the final Walsh-Healey standard.[[12]]The Walsh-Healey standard does not state explicitly that impulse noiseis excluded, as does the ACGIH standard, and the absence of such astatement in the Walsh-Healey standard might be taken to mean that theSecretary rejected this aspect of the ACGIH standard, deciding toinclude impulse noise in Table G-16 calculations. However, the finalWalsh-Healey standard also does not state explicitly that impulse noiseis included in such calculations. In this critical respect, it departedfrom the earlier Walsh- Healey standard, which expressly includedimpulse noise. Moreover, the final Walsh-Healey standard contained theimpulse noise provision and subsection (b)(2), both of which suggestthat impulse noise was to be excluded from Table G-10.Although we cannot determine solely from the standard’s legislativehistory to this point whether the Secretary intended impulse noise to beincluded in Table G-16 calculations, it does reveal several highlysignificant facts: Many of the scientists and organizations whoseattempts to develop criteria for noise were cited by the ACGIH Committeeand the Inter-Society Committee did not believe it either necessary orappropriate for the criteria they developed for steady or continuousnoise to apply to impulse noise. Indeed, it appears that thepreponderant thinking in the scientific community that was cited by theACGIH Committee and the Inter-Society Committee was to exclude impulsenoise from criteria for steady noise. The Labor Department was evidentlyaware of this, for its technical expert on noise served on theInter-Society Committee and was aware of the views of and the limitsdeveloped by the ACGIH Committee. The standard it adopted drew heavilyon the work of the ACGIH Committee and, indirectly, that of theInter-Society Committee. There is also strong evidence that theDepartment of Labor agreed with the body of scientific opinion cited bythe ACGIH Committee and the Inter-Society Committee.On December 4, 1970, after the noise standard was adopted under theWalsh-Healey Act, the Labor Department’s Bureau of Labor Standardspublished Bulletin334 , Guidelines to the Department of Labor’s Occupational NoiseStandards for Federal Supply Contracts (Dec. 4, 1970), a detailed manualexplaining to government contractors what their duties were. The 1970version [[13]] of Bulletin 334 states in part:Table 1 [equivalent to Table G-16] indicates [excessive noise] …….Employees must not be exposed to steady sound levels above 115 dBA,regardless of the duration………The \”slow\” response [on the sound level meter] is anothersetting …….. . which causes it to average out high level noise ofbrief duration (such as hammering), rather than responding to theindividual impact noises._Impulse or Impact Noise_The last sentence in paragraph (d) of section 50-204.10 states:\”Exposure to impulsive or impact noise should not exceed 140 dB peaksound pressure level.\”This sets the upper limit of sound level to which a person should beexposed, regardless of the brevity of the exposure.In contrast with the 115 dBA upper limit for steady noise, the higherintensity for impact noise is permissible because the noise impulseresulting from impacts, like hammer blows or explosive processes, ispast before the ear has time to react fully. Impact noise levels are tobe measured only with an impact meter or an oscilloscope._Variable Noises_Paragraph (c) of section 50-204.10 states the final consideration indetermining whether or not a permissible sound level is being exceeded:\”(c) If the variations in noise level involve maxima at intervals of 1second or less, it is to be considered continuous.\”This means that where the sound level meter on the A scale at slowresponse moves up from a generally steady reading, say from 88 to 92 dB,at intervals of one second or less, the high reading shall be taken asthat to be used in Table 1 [equivalent to Table G-16].As a corollary to this, intermittent sounds of brief duration atintervals greater than one second should, as far as practical, bemeasured as to intensity and duration and the total duration over a daybe ascertained. This total should be entered in the equation given infootnote 1, Table 1, to determine the permissible limit. Theseintermittent sounds, which can be measured with a sound level meter,should not be confused with impulse sounds of very short durationresulting from impacts or explosions.Id. at 2, 6-7 (emphasis added).Bulletin 334 went on to state that noise levels were to be measured witha sound level meter, set for A scale and slow response, meeting thespecifications for sound level meters established by the AmericanNational Standards Institute (ANSI) in ANSI S1.4-1961, \”Specificationfor General- Purpose Sound Level Meters.\” Bulletin 334 at 14. This ANSIstandard contains the following provisions:_Introduction_It should also be recognized that the ballistics and othercharacteristics of the indicating instrument are adapted mainly formeasuring ordinary machinery noises and other sounds of a reasonablyconstant character. For intermittent sounds, and more particularly forrepetitious sounds involving high peak-to-average ratios in soundpressure, and for impact noises, other specialized equipment will berequired in place of the ordinary indicating instrument.ANSI S1.4-1961 at p. 6 (emphasis added).Several significant points emerge from Bulletin 334. The explanation ofwhy a higher peak level. is permitted for impulse noise than for steadynoise-that the ear does not react fully to impulse noise–supplies areason why impulse noise would be excluded from Table G-16. Thestatement indicates that the Secretary was aware of the scientificreasons why the investigators who had developed criteria by 1969 forsteady noise did not apply their criteria to impulse noise. Theinstruction in Bulletin 334 about including \”intermittent sounds ofbrief duration\” in dosage calculations, coupled with the caveat againstconfusing such sounds with impulse noise, is tantamount to an explicitstatement that impulse noise is to be excluded from such calculations.Finally, the provision in ANSI S1.4-1961 that standard sound levelmeters cannot be used to measure impulse noise, together with thestatement in Bulletin 334 that sound level meters used for noise surveysmust conform to ANSI S1.4-1961, is a further indication that impulsenoise is excluded from the standard except for the 140 dB peak levelprovision.[[14]]C. OSHA’s Enforcement and Later InterpretationsThe record also shows that it was OSHA’s practice to exclude impulsenoise from Table G-16 calculations when enforcing the standard. AnneHart, the OSHAindustrial hygienist who inspected Collier-Keyworth’s plant, answered\”no\” when asked, \”[y]ou are not supposed to include impulse noise inyour dosimeter or sound level meter measurements, are you?\” ThomasRockwell, an expert in noise measurement and control and a consultant tonumerous corporations, testified that he wrote a letter to the ClevelandArea Office of OSHA asking if he was correct in understanding that thestandard excluded impulse noise, and received in response a phone callfrom Fred Boelter, an industrial hygienist in the Chicago office,confirming that understanding. We also note that Dr. John Barry, a noiseexpert employed by OSHA since 1976, wrote in a paper presented at PurdueUniversity in 1979: \”This standard [29 C. F. R. ? 1910.95 (a)-(b)] setsthe 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 soundpressure level for impulse noise irrespective of its duration.\”[[15]]Dr. Barry also was the principal author of a document instructing OSHAindustrial hygienists in the proper techniques for determiningcompliance with the standard. This document was first published on April2, 1979, as OSHA Instruction CPL 2-2.20 and was later incorporated inOSHA’s Industrial Hygiene Field Operations Manual (\”IHFOM\”) as ChapterIV.[[16]] Section C.1.e provided:Where both continuous and impulse noise are present, measure thebackground on the dBA fast mode to determine if the continuous noise isabove the levels found in Table G- 16, 29 C. F. R. ?1910.95.Thus, OSHA instructed its inspectors to determine whether the continuouscomponent alone in a mixture of continuous and impulse noise exceededthe limits of Table G-16. Hart’s acknowledgment that she was notsupposed to include impulse noise in dosage measurements thereforereflected an official, agency-wide practice [[17]]Our understanding of OSHA’s early enforcement practices is further aidedby OSHA’s comprehensive proposal in 1974 to completely replace section1910.95 with a more precise standard. The standard that OSHA thenproposed and the explanation accompanying it indicate that OSHA did notview the existing standard as including impulse noise in dosagecalculations. The proposed standard would have retained the 90 dBA limitin the existing standard but would have coupled that limit withrequirements for a stringent hearing conservation program when theeight-hour time weighted average noise level exceeded 85 dBA. 39 Fed.Reg. 37773, 37774 (Oct. 24, 1974). Although OSHA proposed to retain the90 dBA limit at which engineering controls, administrative controls, andpersonal protective equipment were required, it proposed to draw a sharpdistinction between steady-state noise and impulse noise, explicitlyexcluding the latter from dosage calculations. The proposed standardprovided in part:? 1910.95 Occupational noise exposure.(c) Permissible exposure limits.(1) Steady state noise—single level. (i) The permissible exposure tocontinuous noise shall not exceed an eight-hour time-weighted average of90 dBA with a doubling rate of 5 dBA. For discrete permissible ……limits, refer to Table G-16a [omitted, similar to Table G-16].(ii) Where Table G-16a does not reflect actual exposure times andlevels, the permissible exposure to continuous noise at a single levelshall not exceed [an amount determined by a given formula] where \”L\” isthe workplace sound level measured in dBA on the slow scale of astandard sound level meter….(2) Steady state noise–two or more levels. Exposures to continuousnoise at two or more levels may not exceed [a dose computed by thecumulation formula] where C is the actual duration of …… a givensteady state noise level ……(3) Maximum steady state noise level. Exposure to continuous noise shallnot exceed 115 dBA ……(4) impulse or impact noise. (i) Exposures to impulse or impact noiseshall not exceed a peak sound pressure level of 140 dB.(ii) Exposure to impulses of 140 dB shall not exceed 100 such impulsesper day. ……. For each decrease of 10 dB in the peak sound pressurelevel of the impulse, the number of impulses to which employees areexposed may be increased by a factor of 10.39 Fed. Reg. at 37775. The preamble to the proposed standard explainedwhy OSHA proposed to treat impulse noise in this way:The present OSHA standard recommends that impact or impulse sounds notexceed a peak sound pressure level of 140 dB. The Advisory Committeesuggested that this limit be made mandatory. OSHA. has made an additionto the Advisory Committee’s recommendation with respect to impulse noiseexposure, because the actual exposure is a summation of the peak soundlevels of the impulses and the number of impulses. OSHA proposes tolimit exposure to impulses at 140 dB to 100 per day and to permit atenfold increase in the number of impulses for each 10 dB decrease inthe peak pressure of the impulse. For example, the number of impulsesallowed 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 specifiedseparate exposure limits for steady-state noise and impulse noise, itspreamble gave no indication that OSHA considered the proposed standard adeparture from the existing standard. Indeed, its explanation of theproposed standard indicates that OSHA viewed the 140 dB peak limit asbeing the only provision in the existing standard addressed to impulsenoise. While this falls somewhat short of being a formal interpretationof the existing standard, it supplements the other evidence tending toshow that OSHA had interpreted the existing standard to exclude impulsenoise from Table G- 16.The Secretary asserts that it was not his customary practice to excludeimpulse noise from Table G-16. He cites Turner Co., 76 OSAHRC 108\/A2, 4BNA OSHC 1554, 1976-77 CCH OSHD (P) 21,023 (No. 3635, 1976). rev’d onother grounds, 561 F.2d 82 (7th Cir. 1977), as an example of a casewhere a citation based on impulse noise from power presses was issuedand affirmed. Turner does not support the Secretary’s argument. Theimpulse noise issue was not raised in Turner and the parties stipulatedthat the noise levels exceeded those permitted by Table G-16. 4 BNA OSHCat 1556, 1976-77 CCH OSHD at p. 25,274. Moreover, power press noise isnot inevitably impulse noise. If the noise maxima occur more frequentlythan once per second, a situation that may well have been the case inTurner,[[18]] the noise is defined as continuous by subsection (b)(2) ofthe standard. In any event, even if Turner did involve impulse noise, asingle citation does not show an enforcement policy and does not rebutthe otherwise overwhelming evidence that OSHA interpreted the standardto exclude impulse noise from Table G-16.Bulletin 334 is nearly contemporaneous with the adoption of thestandard, consistent with OSHA’s early enforcement policy, and thereforelikely to reflect the understanding of those in OSHA who drafted thestandard. We cannot, however, say the same of the arguments in theSecretary’s brief. The Commission has generally not consideredinterpretations of standards in the Secretary’s briefs to beauthoritative. E.g., C. F. & I. Steel Corp., 86 OSAHRC _____, 12 BNAOSHC 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 thatinterpretations advanced before the Commission in the Secretary’s briefsoften are interpretations made to support litigation positions. They arenot necessarily interpretations traceable to the intent of thestandard’s drafters. Id.; see Investment Company Institute v. Camp, 401U.S. 617, 626-28 (1971)(counsel’s efforts in litigation are \”hardlytantamount to an administrative interpretation\” of a statute). This is avital distinction, for it is the drafters of a standard who incorporateinto it the policies and compromises that the rulemaking recorddemonstrates are appropriate. To give weight to an administrativeinterpretation not traceable to the standard’s drafters wouldeffectively permit the Secretary to amend the standard without thesafeguards mandated by Congress to afford persons affected by thestandard an opportunity to participate in the rulemaking process.The brief the Secretary filed in this case gives us no reason to believethat the interpretation it advances is traceable to the intent of thedrafters. The brief does not address subsection (b)(2) of the standardand its use of the word \”continuous.\” It does not mention Bulletin 334,or the 1974 proposed standard and its preamble. It does not purport tohave been written or reviewed by lawyers who consulted with the draftersof the standard or who participated in the drafting of the standard. Thebrief does address the 140 dB impulse noise provision but misapprehendsthe events that lay behind its adoption. See note 12 above. It alsorelies on the testimony adduced in this litigation on the harmfulness ofimpulse noise and alludes to the findings OSHA made in 1981 to supportthe hearing conservation amendment, though neither is evidence of whatthe Secretary intended when he adopted section 1910.95(a)-(b). In sum,the Secretary’s brief reflects OSHA’s current appreciation of impulsenoise but provides no insight into what the Secretary of Labor intendedin 1969. It is therefore entitled to no weight here.Bulletin 334 and the Secretary’s early enforcement policy are entitledto considerable weight, however. Bulletin 334 is \”a nearlycontemporaneous interpretation of the standard by its drafter.\”Wheeling-Pittsburgh Steel, 11 BNA OSHC at 1294, 1983-84 CCH OSHD 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 andthe understanding of OSHA officials in the 1970’s, such as Dr. Barry,who were responsible for the standard’s enforcement. And it isconsistent with the rationale behind the 1974 proposed standard, adocument that explicitly established separate limits for impulse noiseand steady-state noise and gave no hint that OSHA viewed this as adeparture from the current standard.The Secretary argues that exclusion of impulse noise \”is fundamentallyinconsistent with [the standard’s] goal of safeguarding human hearing.\”That a standard addresses a problem does not mean that it was intendedto safeguard employees from it entirely. Drafters may lack enoughinformation to justify a comprehensive treatment or to know even how towrite a comprehensive standard. They may therefore decide to regulate astep at a time, going as far as their knowledge carries them and leavingthe rest for another day. That happened here. From its text andlegislative history, from Bulletin 334 and OSHA’s early enforcementpolicy, we find that the drafters of section 1910.95(a)-(b) intended toexclude from Table G-16 impulse noise–that is, noise with sharp energypeaks lasting less than one second and spaced more than one secondapart. We therefore vacate citation items 1a(B) and (D), and 1b(B) and(D), which are based on exposure readings of employees exposed toimpulse noise.III. _Noise Exposure of Employees_The Secretary alleges that Collier-Keyworth employees were exposed tonoise in excess of the standard’s limits and that the company did nottake the precautions required by the standard to protect the employees.The record shows that the noise to which Collier-Keyworth’s employeeswere exposed consisted of a mixture of noise from the machines on whichthey were working and background noise that was present even when theirmachines were not operating. The background noise was purely continuousnoise, i.e., noise of unvarying or slowly varying intensity. The machinenoise basically falls into two categories:(1) purely impulse noise,i.e., noise with sharp energy peaks spaced at intervals greater than onesecond; and (2) noise resulting from impulses spaced less than onesecond apart, which is defined as continuous by the standard and which,for the sake of convenience, we shall call \”quasi-continuous\” noise. Toprove over-exposure, the Secretary introduced into evidence dosimeterreadings that measure an accumulated dosage from all noise present inthe work environment, including impulse noise. We have concluded,however, that pure impulse noise must be excluded from measurements todetermine compliance with Table G-16. Thus, in evaluating the dosimeterreadings introduced by the Secretary, we must determine whether theywere contaminated by sufficient impulse noise to render them unreliablemeasures of compliance with Table G-16 levels. We find, for the reasonsdiscussed in below, that some samples were so contaminated but thatothers were not, for they registered quasi-continuous noise.Collier-Keyworth also argues, however, that dosimeters do not reliablymeasure quasi-continuous noise.A. _The Use of Dosimeters to Measure Quasi-Continuous Noise_Collier-Keyworth argues, and Judge Furcolo agreed, that in impulsivenoise environments, the dosimeters used by OSHA may not be relied on toprove violations of Table G-16 exposure limits because they indicatenoise levels significantly higher than the \”true noise levels.\” Inmaking this argument, the company does not distinguish between pureimpulse noise and quasi-continuous noise.Such a distinction must be made, however, Although pure impulse noisemust be excluded in determining compliance with table G-16,quasi-continuous noise is included. Dosimeter readings in environmentscontaining significant amounts of pure impulse noise are inherentlyunreliable regardless of the accuracy with which they measure impulsenoise, for they should not be measuring such noise at all. They should,however, be measuring quasi-continuous noise, and the accuracy withwhich they measure this type of noise is critical. Thus, we mustconsider Collier- Keyworth’s argument to the extent it questions theaccuracy with which OSHA’s dosimeters measure quasi-continuous noise.We will assume in this discussion that ColIier-Keyworth is correct inits assertion that dosimeters in impulsive noise environments registerdosages as if noise level’s were significantly higher than the \”truenoise levels.\”[[19]] However, Collier-Keyworth’s argument cannotlogically be seen as merely an objection to dosimeters but to thestandard’s prescription of the slow response mode of measurement. As wehave said, a noise dosimeter is in effect a sound level meter withadditional circuitry that automatically records dosages in the mannerset out in the cumulation formula of Table G-16. And, as we shalldiscuss below, the circuitry of a dosimeter that arguably causes it toovercount \”true noise\” levels is not its additional dosage- calculatingcircuitry but the slow response circuitry it shares with conventionalsound level meters. Thus, despite the emphasis in Collier-Keyworth’sbrief on the inability of dosimeters to reliably detect \”true noiselevels,\” its argument could apply with equal force to conventional soundlevel meters. Indeed, Collier-Keyworth’s acoustical engineering expert.Thomas Rockwell, admitted that he would obtain the same results using aslow response sound level meter as a slow response dosimeter.Dosimeters and sound level meters employing slow response seem toovercount the \”true noise level\” because slow response instruments havean integration time of one second, that is, they register an impulse asif it were spread out over a second. A burst of sound lasting one-halfsecond would therefore be displayed as if it were one second long.Because the slow response integration time is longer than the durationof such a noise impulse, the slow response mode distorts the \”true\”noise pattern, making impulses appear longer in duration but lower inpeak intensity.[[20]]Collier-Keyworth argues that the net effect of the slow response mode isto cause dosimeters to read higher than the \”true noise level.\” Theproblem with CoIlier-Keyworth’s argument is that section 1910.95(a)-(b)does not regulate \”true noise levels.\” The standard regulates soundlevels (1) as measured by a standard sound level meter, (2) as detectedby slow response, (3) as weighted by frequency according to theA-weighting network (which weights each sound frequency according to theear’s response to it), (4) excluding impulses more than a second apart,and (5) treating impulses less than a second apart as continuous.Indeed, it is rather pointless to speak of \”true noise levels\” becausethey can never be measured. To measure \”true noise levels\” would requirean ideal instrument having, among other things, an instantaneousresponse time, that is, an integration time of zero. One could build asound level detector with a short response time, perhaps an eighth of asecond, as fast response instruments have. But such an instrument wouldstill not be measuring \”true noise levels.\”Inasmuch as section 1910.95(a)-(b) does not regulate \”true noise levels\”but levels as detected by slow response instruments, Collier-Keyworth’sargument is really a complaint about the standard’s prescription of slowresponse. Collier-Keyworth seems to desire that sound level meters anddosimeters be employed at fast response so as to more closelyapproximate the \”true level\” of impulse noise.[[21]] However, thestandard specifies the use of slow response and whatever deviations fromtrue noise levels that mode introduces were within the contemplation ofits drafters. That slow response instruments give greater weight toimpulse noise than fast response instruments must be regarded as one ofthe many compromises that the Secretary struck when he adopted thestandard. Just as the Secretary could provide that impulses recurring atgreater than one-second intervals not be counted at all, he couldprovide for a measurement technique that gives additional weight toimpulses closer than one second together. Collier-Keyworth does notpoint to any illegality in the Secretary’s choice of slowresponse.[[22]] We therefore reject Collier-Keyworth’s arguments thatslow response dosimeters may not be used to detect exposures greaterthan those permitted by Table G-16. [[23]]B. _Evidence of Exposure_We now consider whether OSHA proved that any Collier-Keyworth employeewas over-exposed to quasi-continuous noise. On April 14, 1980, OSHAindustrial hygienist Anne Hart began an inspection of Collier-Keyworth’splant aimed at determining whether the company was in compliance withthe noise standard. Hart attached General Radio Model 1954 dosimeters tofive Collier-Keyworth employees, who wore the dosimeters throughouttheir work day. One of the dosimeters malfunctioned, and Hart returnedon April 18 to obtain a dosimeter reading for that employee. Hart alsomeasured the noise levels in the employees’ hearing zones at varioustimes throughout the inspection by using a sound level meter. Theemployees who were sampled operated power presses and lathes in fourdifferent areas of the plant.Presses 2208, 2209, and 2210 (citation items 1a(A)) and 1b(A)) are60-ton Bliss open-back inclinable power presses used by Collier-Keyworthto fabricate metal parts. The presses operate automatically. Sheet steelis fed into the press bed by a feeder mechanism. A die attached to a ramabove 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 threepresses were located within ten feet of each other.The presses were operated by Paul LeBlanc and Norman Melanson. Theoperators’ duties including changing dies, making necessary adjustments,installing coils of sheet steel stock, threading the stock into the diearea, and monitoring the operation of the presses. An operator had to bein the general area of the machines while they were operating, but theoperation of each machine did not have to be monitored closely.Using a sound level meter, Hart measured noise levels in the vicinity ofthe presses ranging from 85 to 104 dBA, with readings below 90 dBAoccurring only when none of the presses were operating. The dosimeterworn by LeBlanc read 305% it the end of the day, and that worn byMelanson read 286%. These readings indicate that both employees wereexposed to approximately three times the permissible dose, or, viewed adifferent way, that they were exposed to time-weighted average soundlevels of about 97.6 dBA and 98.0 dBA. See 29 C.F.R. ? 1910.95, AppendixA, Table A-1 (hearing conservation standard). Hart testified that shetimed the presses using a watch with a second hand and found that theimpacts for each machine were less than one second apart. She alsostated that the strokes of the three machines were not synchronized, sothat when all three presses were running, the noise peaks were less thanone-third second apart.Collier-Keyworth’s chief engineer, Robert Cochran, testified that thepresses had a maximum stroke rate of 80 per minute. The actual strokerate was controlled automatically by the feeder mechanism and wasdifferent for each part being produced. Each machine was used to produceabout 30 different parts. Cochran did not know the stroke rates thatcorresponded to the various parts.Following the inspection, noise measurements were made inCollier-Keyworth’s plant by experts for both parties: Thomas Rockwellfor Collier-Keyworth and John Barry for the Secretary. Both experts fedthe output from sound level meters into strip-chart recorders, whichdraw tracings showing how the noise level’s fluctuate with time.Tracings made by Rockwell on June 17, 1980, show press 2208 operating at57.5 strokes per minute, press 2209 at 48 strokes per minute, and press2210 at 56 strokes per minute. Rockwell testified that Cochran told himthat 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 seriesof impulses less than one second apart is treated as continuous. Thisquasi continuous noise will be produced by a press operating at a strokerate of more than one per second, or sixty per minute. A press strokingslower than once per second will, however, generate impulse noise.Collier-Keyworth’s presses can stroke as fast as eighty per minute, butthe actual rate depends on the part being produced and for some parts isslower than sixty per minute. Collier-Keywortn’s presses thereforegenerate quasi-continuous noise at certain times and impulse noise atother timesThe evidence shows that LeBlanc and Melanson were exposed only toquasi-continuous noise on the day of the inspection. Hart testified thatshe timed the presses and that the time between strokes was less thanone second for each press. There is no evidence directly contradictingHart’s testimony.[[24]] Collier-Keyworth production records showing theparts produced on the day of the inspection were introduced intoevidence, but the company presented no evidence on the stroke rates thatcorresponded to those parts.Collier-Keyworth did show that on a later date, when Rockwell measuredthe noise from its presses, the presses were stroking slower than onceper second, indicating that the noise at that time was impulse noise.Moreover, Rockwell testified that Cochran had told him that the presseswere producing some of the same parts when he was in the plant as whenHart made her inspection. However, Rockwell spent parts of three days inthe plant, and the production records introduced into evidence show thatthe presses typically produced different parts on different days.Therefore, during the three days Rockwell was in the plant, the pressesprobably produced several different parts each, including some that weremade during Hart’s inspection and others that were not. In the absenceof evidence that the parts produced when Rockwell made the strip chartrecordings showing the presses operating slower than once per secondwere the same as those manufactured during Hart’s inspection, Rockwell’stestimony 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 thenoise heard by an employee, that the standard regulates. During mostLeBlanc’s and Melanson’s workday, two or three presses were operatingand generating noise. As the presses were not synchronized, the noisemaxima that they heard would have occurred about twice per second withtwo presses running and about three times per second with three pressesoperating. In any event, because each press individually producedquasi-continuous noise, two or three presses operating at individuallyproduced quasi- continuous noise, two or three presses operating at thesame time would also produce quasi- continuous noise.Because LeBlanc and Melanson were exposed only to quasi-continuousnoise, their dosimeter readings did not include any measurements ofimpulse noise. Those dosimeter readings–305% for LeBlanc and 286% forMelanson–facility indicate exposure that exceeds permissible limits.Collier- Keyworth asserts that a number of factors can affect dosimeterreadings, including electromagnetic fields or radio waves, wind,orientation of the microphone, chemicals, temperature effects, moisture,and noise made by the employee wearing the dosimeter. There is noevidence, however, that any of these factors significantly distorted thedosimeter readings made during the OSHA inspection of Collier-Keyworth’splant. The dosimeter readings obtained by industrial hygienist Hart areconsistent with sound level meter readings she made on the day of theinspection as well as with measurements made on later days by Rockwelland Barry. Hart measured the noise level in LeBlanc’s hearing zone to be99-102 dBA when LeBlanc was standing by press 2208 with presses 2208 and2209, 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 bothLeBlanc and Melanson with none of the presses running. Hart noted,however, that all three presses were usually running during herinspection. Also, chief engineer Cochran testified that Collier-Keyworthhad no excess press capacity, indicating that the presses operatedfull-time except when dies were changed or adjustments made.As noted above, the dosimeter readings Hart obtained for both LeBlancand Melanson were approximately 300% of the permitted daily dose. Anemployee exposed to a constant noise level of 100 dbA for 6 hours wouldreceive a dosage of 300%. The sound level meter readings made by Hartshow that LeBlanc and Melanson were sometimes exposed to noise levelsless than 90 dBA, out were exposed to noise levels around 100 dBA formost of their 8-hour shifts. Thus, the sound level meter readings tendto show that the dosimeters were accurately measuring and recording thenoise levels to which LeBlanc and Melanson were exposed.In summary, we conclude that on April 14, 1980, LeBlanc and Melanson,the operators of presses 2208, 2209, & 2210, were exposed to noise inexcess of the limits permitted by Table G- 16.Press 2216 (items 1a(C) and 1b(C)) is a 60-ton Bliss press similar tothe three presses discussed in the previous section but located somedistance from them. In April 18, 1980, industrial hygienist Hartattached a dosimeter to press operator Alan Sund. After 202 minutes, orabout 3.3 hours, the dosimeter read 167%. Sound level meter readingsmade by Hart in Sund’s hearing zone at four different times over theperiod the dosimeter was operating were 103-107 dBA while the press wasrunning. Sund was then observing the machine from a distance of one totwo feet. As with the other presses, Hart testified that she timed thestroke rate and that the time between strokes was less than one second.On June 17, 1980, Rockwell measured the stroke rate of the press to be45 strokes per minute, but there is no evidence that the press wasproducing the same part, and thereby running at the same speed, asduring Hart’s inspection.For much the same reasons as previously discussed, we find that theevidence shows Sund was exposed to noise exceeding the standard’spermitted limits. Hart’s testimony that the time between strokes wasless than one second on the day the inspection establishes that thenoise was continuous within the meaning of the standard. The dosimeterreading facially indicates that Sund was exposed to excessive noise. Thesound level meter readings indicated that Sund was exposed to 103-107dBA for about 3.3 hours. At 103 dBA, the lowest sound level or thisrange, only about 1.3 hours of exposure is permitted. Thus, the soundlevel meter readings corroborate the measurement of excessive exposuremade by the dosimeter.Press 352 (items 1a(D) and 1b(D)) is a manually-fed machine used forsmall bending jobs. On April 14, 1980, Hart obtained a reading of 256%from a dosimeter attached to press operator Ernest Couture. According toHart, the press strokes once every two or three seconds. With themachine not operating, Hart measured the noise in Couture’s hearing zoneto be from 84 to 88 dBA. With the machine operating, she measured noiselevels as high as 95 dBA.We conclude that the Secretary did not prove Couture was exposed toexcessive noise. Because the press stroked only once every two to threeseconds, the noise that resulted from the press’s operation was impulsenoise, which is not regulated by Table G-16. The only continuous noiseto which Couture was exposed was background noise measured to be 84 to88 dBA, levels within the standard’s limits for any exposure time. Wetherefore find that Couture was not exposed to noise exceeding thestandard’s limits and we will vacate Items 1a(D) and 1(b)(D)).Lathes 6040 and 3018 (items 1a(B) and 1b(B)) are used to cut metaltubing and chamfer the ends. Both lathes were operated by a singleemployee, Ken Thompson. Lathe 6040 was operated manually, while lathe3018 was automatic. Therefore, when both lathes were operating, Thompsonwould be standing beside lathe 6040. On April 14, 1980, a dosimeterattached to Thompson during his shift yielded a reading of 158.5%.According to sound level meter readings made by industrial hygienistHart, the noise level in Thompson’s hearing zone ranged from 85 to 107 dBA.Lathe 6040 was relatively quiet and, when operated alone, produced noiselevels below 90 dBA. Thus, the noise that caused the standard’s limitsto be exceeded was generated by lathe 3018. That lathe sometimes emitteda very loud high-pitched squeal, but at other times the squeal wasmissing. Hart recorded noise levels of 107 dBA when the squeal wasevident, but only 92 dBA with both lathes running but no high-pitchedsqueal present. When Dr. Barry later visited Collier- Keyworth’s plant,he measured 118 dBA in the hearing zone of the operator of lathe 3018.Upon analyzing the frequencies contained in the noise, Barry found thatthe 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 recordings show very pronounced short bursts of noise, much likethe strip chart recordings for the power presses. The charts are notlabeled with time scales that would enable the time between bursts to bemeasured, but Rockwell testified that the charts show a peak-to-peakseparation greater than one second, indicating that at least some of thenoise is impulse noise.We conclude that the Secretary failed to prove Thompson was exposed toexcessive noise. Some of the noise to which Thompson was exposed, andwhich was detected by the dosimeter, was impulse noise that must beexcluded under the standard. There is no basis to conclude thatThompson’s dosimeter reading would have shown overexposure if theimpulse noise had been excluded. Indeed, it is doubtful that theSecretary proved overexposure even assuming that impulse noise were tobe included. Industrial hygienist Hart testified that Type 2 sound levelmeters and dosimeters, the type she used in her inspection, generallyhave an inherent error factor of two dBA; when that error is cumulatedover time, it creates a potential error of 32% in the dosimeterreading.[[26]] Thus, a dosimeter reading of 158.5%, as was obtained forThompson, would generally be outside the instrument’s range of error andwould show overexposure. However, the record shows that the noise towhich Thompson was exposed was of very high frequency, predominantly8000 hertz. At 8000 hertz, type 2 sound level meters and dosimeters havean inherent error factor of 6.5 dBA.[[27]] This means that a dosimetercontaining a Type 2 sound level meter would have to read over 240% toshow overexposure once the inherent error of the instrument at 8,000hertz is taken into account. Cf. 29 C.F.R. ? 1910.95, Appendix A, TableA-1 (hearing conservation standard) (entry for 96.3 dBA corresponds todose of 240 percent). Thus, where the noise is predominantly at 8,000hertz, a dosimeter reading of 158.5%, the reading obtained for Thompson,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 that OSHA proved over-exposure to quasi-continuous noise bypress operators LeBlanc, Melanson and Sund–the employees involved initems 1a(A) and (C), and 1b(A) and (B)–we must now determine whetherthe Secretary showed that Collier-Keyworth violated the standard byfailing to take required precautions against excessive noise exposure.IV. _Precautions Against Noise Exposure_The Secretary alleges in citation item 1a that Collier-Keyworth violatedsection 1910.95(a) by failing to enforce the use of hearing protectionequipment. In item 1b, he alleges that the company violated section1910.95(b)(1) by failing to implement feasible administrative orengineering 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 threeemployees to wear personal hearing protectors. Industrial hygienist Hartobserved LeBlanc and Melanson wearing earmuffs and Sund wearing Swedishwool earplugs during her inspection. Hart testified, however, that shealso observed the employees \”at one time or another\” not wearing hearingprotection. The Secretary relies on Hart’s testimony that she observedthe 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 the standard, employees may be exposed to noise levels lessthan 115 dBA for some period of time without using protective equipment.Also, at various times the three employees were subjected to noiselevels less than 90 dBA, where no protection is required regardless ofthe length of exposure. Thus, Hart’s testimony that she observed theemployees at times without protection does not prove a violation of thestandard. If anything, the evidence that the employees were sometimesobserved wearing hearing protection tends to show that Collier-Keyworthcomplied 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) thatCollier-Keyworth violated section 1910.95(b)(1) by failing to implementfeasible engineering controls on presses 2208, 2210, and 2216.[[29]] Hisexpert witness on engineering controls, Dr. Barry, proposed two basicnoise reduction techniques he believed were feasible: enclosing the dieareas on the presses; and replacing the existing air ejection nozzleswith quieter ones.Each press forms metal parts by the force exerted by a rapidlydescending die on sheet steel in the bed of the press. Barry testifiedthat there were two primary sources of noise associated with theoperation of a press: (1) noise from the impact of the die on the sheetmetal stock; and (2) noise from the air ejection nozzles used to expelthe parts from the press bed. Barry recommended isolating the pressoperators from these noise sources by installing acoustical enclosuresaround the die areas of the presses.[[30]] He testified that theenclosures would have to be designed \”to minimize any operatorencumbrances and allow for ease of die change.\” The enclosures, inBarry’s opinion, should be made of sheet metal, with transparent plasticpanels to permit visual observation of the die area. Doors and openingsshould be tightly sealed, and the inside of the enclosure should belined with acoustically absorptive material to prevent sound buildup.Barry believed that each press enclosure would cost $3,500 to $4,000 todesign, fabricate, and install, and that a reduction in noise level of10 dBA could be achieved. Barry had seen similar enclosures in use atanother company’s plant and believed those enclosures achieved a 10 dBAreduction without inhibiting production.The enclosures Barry recommended would enclose the air ejection nozzlesas well as the die impact area, and would therefore reduce noise fromboth sources. Barry also testified that the air noise could be reducedeven if the die areas were not enclosed. Either quieter nozzles thatwere commercially available could replace the existing nozzles, or thevelocity of air from the existing nozzles could be reduced to lessen thenoise. Barry stated that the commercial nozzles would cost $5 to $20each and would, in his opinion, produce a significant reduction in thenoise level.Curtis Holmer, a noise control engineer who testified forCollier-Keyworth, did not believe that enclosing the die areas of thepresses would significantly reduce the impact noise emanating from thepresses. Holmer testified that enclosing the die area can significantlyreduce the noise from a press only when the force the press exerts isconsiderably below its capacity. However, when a press is used at ornear its capacity, as the presses were at Collier-Keyworth, then most ofthe energy of the impact is transferred from the die area to the frameof the press, and most of the noise the press produces radiates from itsframe instead of from the point of impact. Holmer therefore believedthat enclosing the die area alone, as recommended by Barry, would notreduce the noise resulting from the impact of the die on the stock. Theenclosures would reduce only the air ejection noise, and Holmer thoughtthis noise reduction would be on the order of 3 dBA or less.Chief Engineer Cochran testifed that die enclosures would severelyrestrict the productivity of the presses by increasing the timenecessary for the operators to perform any duty requiring access to thedie area. Cochran reviewed the production reports prepared by theoperators for a four-week period to determine how often they neededaccess to the die area. Estimating that each instance of access wouldrequire 30 extra minutes if the dies were enclosed, he calculated thatthe company would have lost 72 hours of production over the four-weekperiod, or about 950 hours for a year.[[31]] Since the company had noexcess press capacity, it would have to purchase a new press to maintainits current level of production. According to Cochran, a new press wouldcost $55,000. A plant addition to house the machine would cost anadditional $18,000, and a new operator would have to be hired to run themachine at a cost of $24,000 per year. Cochran also noted that the dataon which he based these estimates might under-state the number of timesthe operators needed access to the dies because the operators might notrecord situations that were now very easy to resolve, such as clearingout a piece of scrap from the die area.Regarding Barry’s suggestion that the existing air ejection nozzles bereplaced with quieter ones, plant engineer English testified that thecompany had tried using quieter nozzles in 1977 but that those nozzlesreduced the air velocity below what was needed to eject the parts fromthe press bed. Curtis Holmer explained that quiet nozzles obtain theirnoise reduction by reducing the air velocity and by spreading out theair stream over a larger area. However, for small parts such asCollier-Keyworth made, much of the air from such nozzles would blow pastthe part and be ineffective in moving it.In Sherwin-Williams, 11 BNA OSHC at 2110, 1984-85 CCH OSHD at p. 34,702,the Commission stated what the Secretary must prove to show a violationof section 1910.95(b)(1):To prove a violation, therefore, the Secretary must prove that proposedengineering and administrative controls are both technologically andeconomically feasible. As the Ninth Circuit recognized in Castle &Cooke, \”realism and common sense should dictate how the Secretary maymeet his burden of providing substantial evidence of feasibility.\” 692F.2d at 650. After the Secretary proves that controls aretechnologically feasible, the burden of producing evidence shifts to theemployer, who may raise the issue of economic feasibility and go forwardwith evidence of the cost of controls and personal protective equipment.The burden of producing evidence then returns to the Secretary, \”whomust establish that the benefit of the proposed engineering controlsjustifies their relative cost in comparison to other abatement methods.\”Id. The ultimate burden of persuasion on the feasibility issuenevertheless remains with the Secretary.The Secretary clearly did not prove the feasibility of reducing the airejection noise by installing quieter nozzles. Although quieter nozzlesare commercially available, Collier-Keyworth had tried such nozzlesseveral years before the alleged violation and found that the reducedvelocity of air they produced provided insufficient force to eject theparts from the die area. Thus, such nozzles would not accomplish theirintended purpose and would be technologically infeasible.We also find that the Secretary failed to prove the feasibility of dieenclosures. The enclosures would produce a minimal benefit insufficientto justify their substantial cost.The enclosures Barry recommended would surround the die areas of thepresses and isolate the operators from the noise produced by the impactof the die on the stock and the noise from the air ejection nozzles.Barry believed that such enclosures could reduce noise levels about 10dBA. Collier-Keyworth’s expert, Holmer, testified that the enclosureswould produce only about a 3 dBA reduction. In Holmer’s view, the dieenclosures would only reduce the air ejection noise reaching theoperators, and not the noise from the die striking the stock.We give considerable weight to Holmer’s opinion. Holmer had lengthyexperience in the measurement and control of industrial noise and was amember of the lnstitute of Noise Control Engineering, a nationalorganization of competent noise control professionals. He provided areasoned explanation for his conclusion that die enclosures on Collier-Keyworth’s presses would not substantially reduce impact noise and wefind his testimony persuasive. Barry’s opinion that enclosures couldachieve a 10 dBA reduction is entitled to much less weight thanHolmer’s. Barry’s training was primarily in measuring the effects ofnoise on the human ear rather than the analysis and reduction ofindustrial noise by engineering means. Barry had not designed orimplemented industrial noise controls and was not a member of theInstitute of Noise Control Engineering. Moreover, Barry’s opinion wasbased only on his belief that die enclosures at another company hadachieved a 10 dBA reduction. Holmer’s testimony indicates, however, thatthe noise reduction produced by a die enclosure depends on the degree ofcapacity at which the press is used. Thus, achievement of a 10 dBAreduction at another company, in the absence of evidence of similarconditions, is a tenuous basis for believing that Collier-Keyworth couldobtain a comparable reduction. We find that the die enclosuresrecommended by Barry would achieve a reduction of about 3 dBA in thenoise levels to which Collier-Keyworth’s press operators were subjected.A reduction of 3 dBA is significant (see Continental Can Co., 76 OSAHRC109\/A2, 4 BNA OSHC 1541, 1543 n. 8, 1976-77 CCH OSHD (P) 21,009, p.25,253 n. 8 (No. 3973, 1976)), but it must be balanced against the costsof engineering controls and considered in light of other protectivemethods. See Sherwin-WiIliams, 11 BNA OSHC at 2110, 1984-85 CCH OSHD atp. 34,702. The other method that we consider here is the personalprotective equipment that Collier-Keyworth’s employees now wear. Dr.Victor Hildyard, a medical doctor specializing in diagnosis andtreatment of diseases of the ear, testified that earplugs and earmuffsof the type used by Collier-Keyworth’s employees could reduce the noisereaching the employee’s inner ear by 30 dBA if worn properly. Even ifloosely fitted, the equipment would reduce noise levels by 10-15 dBA.Thus according to Dr. Hildyard, a noise reduction of 10 dBA is readilyachievable even if the performance of the equipment is far less thanideal. The highest time- weighted average sound level to whichCollier-Keyworth’s press operators was exposed was about 98 dBA.[[32]]Thus, if engineering controls were not required at all, the personalprotective equipment would very likely meet Collier-Keyworth’sobligation under section 1910.95(b) to \”reduce sound levels within thelevels of the table.\” Yet, even if engineering controls were installed,the employees would still have to wear the personal hearing protectorsbecause a 3 dBA reduction would not reduce noise to within Table G-16limits. They would simply not have to wear it for as long as they nowmust. Thus, installing die enclosures would not eliminate the need forpersonal protective equipment but would only decrease the amount of timeemployees must wear it.The cost of the controls is, however, substantial. According to Barry,each enclosure would cost $3,500 to $4,000 to design, fabricate, andinstall. Moreover, to maintain its current level of production,Collier-Keyworth would have to purchase a new press for $55,000, andwould incur additional costs associated with the new press, including adie enclosure for that press as well. The new press would add a noisesource to Collier-Keyworth’s plant and could result in additional noiseexposure for some employees. On balance, we are not convinced that thebenefits to be gained from the enclosures justify these costs. Wetherefore find that the die enclosures recommended by Barry were notshown 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 involve employee exposure to impulse noise, unless the Secretaryrequests an opportunity within 15 days of this decision to rebutofficially-noted documents with evidence of the Secretary’s intent in1969. We vacate items 1a(A) and (C) because the Secretary failed to showthat employees were not wearing personal hearing protectors for theperiods required. And we vacate items 1b(A) and (C) because theSecretary failed to show that proposed engineering controls werefeasible. The judge’s decision is therefore affirmed.FOR THE COMMISSIONRay H. Darling, Jr.Executive SecretaryDATED: April 6, 1987_Appendix_1. The noise standard proposed by the ACGIH committee in 1968 stated in1968 stated in part:Average Sound Pressure A-Weighting Duration ofLevels Of Octave Bands Network of Exposure perwith Center Frequencies Sound Level Dayof 500, 1000, and 2000 Hz Meter_______________________________________________________dB dBA Hours85 92 4 – 890 97 2 – 495 102 1 – 2100 107 less than 1 hour_______________________________________________________These values apply to total time of exposure per working day regardlessof whether this is one continuous exposures but dies [sic] not apply toimpact or impulsive type of noises.When the daily noise exposure is composed of two or more periods ofnoise exposure of different levels, their combined effect should beconsidered, rather than the individual effect of each. If the sum ofthe following fractions:C1\\T1 + C2\\T2 + ……..Cn\\Tnexceed unity, then, the mixed exposure should be considered to exceedthe threshold limit values[.] C1 indicates the total time of exposure ata specified noise level, and T1 indicates the total time of exposurepermitted at that level.The above limits do not apply to impulse or impact type pf noise. It isrecommended that exposure to this type of noise should not exceed 140 dBpeak sound pressure level.Appendix 1 of Herbert H. Jones, \”ACGIH’s Proposed Threshold Limit Valuefor Noise,\” 29 AM. Indus. Hygiene J. 537-40 (Nov. – Dec. 1968)(_ACGIH_).2. A paper cited by both the Inter-Society Committee and the ACGIHCommittee and that proposed criteria for steady noise concluded with thefollowing observation :We have purposely omitted any discussion of impulse noise up to now, forvery sound reasons. We know very little about the effects of impulsenoise on the ear. We have just started an intensive study of therelations between impulse noise and TTS (temporary threshold shifts, aform of hearing loss).The problem does not lend itself to easy solution, for several reasons.Measuring impulse noise is difficult to begin with, but not nearly asdifficult to resolve as determining the effect the middle ear muscleshave on the transmission of impulsive noise across the middle ear.Limited laboratory research indicates that the laws governing TTS fromexposure to steady noise (non-impulse) do not operate for impulsivenoise exposure. Actually, this should not be surprising, since theresponse of the basilar membrane to steady noise and to impulse noiseshould be completely different.For the present, we can only say that no one should be habituallyexposed to impulse noise of any considerable magnitude without the useof hearing conservation measures.Our very limited knowledge of the effects of impulse noise prevents anymeaningfui discussion of impulsive-type noise exposure.A. Glorig, W.D. Ward, & J. Nixon, \”Damage Risk Criteria andNoise-Induced Hearing Loss,\” 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 proposedcriteria for hearing conservation with the following caveat:Our knowledge of the relations of hearing loss to noise-exposure permitsus to propose guidelines for establishing standards for preventingsignificant noise- induced hearing loss in the majority of exposedpersons. These recommended standards have been proposed by theInternational Organization for Standardization. They are presented belowin brief modified form. They do not apply to exposure to impulsive noisebut only to steady noise.Subcommittee on Noise, Committee on Conservation of Hearing, Am. Acad.of Ophthalmology and Otolaryngology, Guide for Conservation of Hearingin Noise 13 (1964) (emphasis in original), cited in I-S at 424 ref. 9.4. A 1966 publication of the American Industrial Hygiene Associationreviewed the criteria for recommended noise limits that had beenproposed by various investigators up to that time. While noting thatthere was little disagreement as to the levels of continuous noise thatwere harmful, the publication went on to say:Much more difficult will be the selection of mandatory protection levelsfor intermittent, short duration, and impact noises . . . . Becausethere is still much to be learned about the relationships betweentemporary and permanent threshold shifts the criteria for briefexposures cannot be expected to have the same reliability as those forcontinuous exposures. Until more is known about short-time exposures,the criteria should be treated as temporary benchmarks and be used withconsiderable judgment.Am. Indus. Hygiene Ass’n., Industrial Noise Manual, ch. 7, at 59-60 (2ded. 1966), cited in 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 toassess damage risk from impulse noise exposure. R. Coles, G. Garinther,D. Hodge, & C Rice, Criteria for Assessing Hearing Damage Risk FromImpulse-Noise Exposure, U.S. Army Tech. Memo.13-67 (Aug. 1967), cited inACGIH at 539 ref. 12 (article).[[33]] These studies tended to seekpermissible exposure criteria in terms of factors unique to impulsenoise. Several of the studies demonstrated that exposure to 25-100impulses in the 140-170 dB range at 6-30 impulses per minute couldproduce temporary threshold shifts (\”TTS\”)[[34]] in a significant numberof exposed persons. The variations in the TTS’s of people exposed tosuch impulse noise was greater than among subjects exposed tosteady-state noise, indicating that some people may be particularlysusceptible to impulse noise. Responses were observed to vary dependingon whether the noise reached the ear at normal or grazing incidence; insome 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 harmful than noise from a gun fired by a subject himself,which would reach his ear at grazing incidence. TTS’s were greater forlonger duration impulses of similar peak intensity, a result probablyattributable to the greater energy associated with the longer impulses.The paper drew from the studies criteria for peak pressure level andduration limits that would not produce an excessive risk of hearingloss. It concluded that impulses in the 155-160 dB peak intensity rangewere safe for a duration of about 10 milliseconds, with higher intensityimpulses 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 wascustomary in proposing damage risk criteria for steady-state noise toexclude impulse noise by implication rather than by direct statement. R.Coles, G. Garinther, D. Hodge. and C. Rice, \”Hazardous Exposure toImpulse Noise,\” 43 J. Acous. Soc. 336 (1968), cited in ACGIH at 539 ref.11 (article). After discussing risk factors associated with commonamounts of exposure to gunfire, the paper said, \”the more industrialtypes of impulse-noise exposure as in riveting, pile driving, dropforging, etc., may require a separate criterion or may be treatable bysteady-state noise criteria.\” Id. at 339. However, the authors concluded:[w]hether a more general continuity between impulse and steady-statenoise criteria can ever be achieved seems very uncertain in view of theevident differences in their ranges of TTS and of opinion such as thatof Kryter and Garinther that PTS from impulse noise may follow adifferent pattern from PTS due to steady-state noise._Id_. at 343 (reference omitted).7. Investigators attempted to determine the combined effect of impulsenoise and steady-state noise in only one cited study. A. Cohen, B.Kylin, and P. LaBenz, Temporary Threshold Shifts in Hearing FromExposure to Combined Impact\/Steady-State Noise Conditions, 40 J. Acous.Soc. 1371 (1966), cited in ACGIH at 539 ref. 10 (article). An experimentwas conducted on 15 subjects, who were exposed to a variety ofcombinations of impulse and steady-state noise. The study found that,under some circumstances, impulse noise in the presence of continuousnoise was less harmful to hearing than the impulse noise alone. Theauthors concluded that this was due to the \”acoustic reflex,\” which is acontraction of the middle ear muscles that attenuates the amount ofsound transmitted to the inner ear. If the acoustic reflex is activatedbefore exposure to a loud impulse, the inner ear receives protectionfrom the impulse. Therefore, when the subjects were exposed to steadynoise that was loud enough to activate the acoustic reflex, the impulsenoise was not as damaging as it otherwise would have been.8. The standard proposed by the Department of Labor under theWalsh-Healey Act on September 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 theworking environment shall not exceed 85 decibels. Every employer shallutilize every feasible engineering method to control noise levels. Suchmethods of control include reducing the amount of noise produced at thesource, reducing the amount transmitted through the air, andsubstituting quieter procedures or machinery.(b) Where the noise is not steady the equivalent steady noise level isdetermined by the following procedure: The duration over 1 week of eachclearly distinguishable sound level is located in column 1 of Table 1following this paragraph (b) and the partial noise exposure is read atthe intersection of this row with the appropriate sound level column.The partial noise exposures thus obtained are added arithmetically. Thesum is the composite noise exposure. The continuous noise exposureequivalent to the composite noise exposure is then read from Table IInext following Table 1. If the variations in noise level involve maximaat intervals of 1 second or less it is to be considered steady. If theintervals are more than one second and the duration of the maxima areless than 1 second each, maximum is to be considered as 1 second.TABLE I.. Duration \/WeekThe table referred to above is not available in this format.Please telephone the Review Commission Public Information Office,202-5398, to request a paper copy:; TTY: 202-606-5386; FAX:202-606-5050; e-mail: [email protected] Table IIThe table referred to above is not available in this format.Please telephone the Review Commission Public Information Office,202-5398, to request a paper copy:; TTY: 202-606-5386; FAX:202-606-5050; e-mail: [email protected] SECRETARY OF LABOR,Complainantv.COLLIER-KEYWORTH CO.,RespondentOSHRC DOCKET NO. 80-2848APPEARANCES:Robert Yetman, Esq., for Complainant Douglas B. M. Ehlke, Esq., forRespondent_DECISION AND ORDER_This is a proceeding pursuant to the Occupational Safety & Health Act of1970, as amended (29 USC, sec. 651 et seq.) hereinafter called the Act.The Complainant alleges that the Respondent has violated sec. 5(a)(2) ofthe Act (sec. 654) by not complying with the Occupational Safety &Health standards.The Respondent is a corporation engaged in the business of manufacturingchair mechanisms and its business affects the commerce of the UnitedStates.The Respondent’s worksite at Gardner, Massachusetts, was inspected bythe Occupational Safety & Health Administration (hereinafter calledOSHA) on or about April 9 – 18, 1980.On or about April 28, 1980, the following Citation, together with Noticeof Proposed Penalty, was issued against the Respondent: Citation #1,Items 1a – c, the serious violation of the standards at 29 CFR1910.95(a), .95(b)(1), and .95(b)(3); respectively Items 1a, b and c ofCitation #1.On May 16, 1980, the Respondent filed Notice of Contest to Items #1a-cof Citation #1 and the 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 thisdecision under appropriate titles. The basic issue is whether or not theRespondent’s employees were exposed to noise exceeding the limits ofTable 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] AND MARCH 23 and 24, 1982, THE 1981 TRANSCRIPT WILL BEREFERRED TO BY MONTH AND PAGE NUMBER [E.G., MARCH 225] AND THE 1982TRANSCRIPT BY YEAR, MONTH, AND PAGE NUMBER BECAUSE SOME OF THETRANSCRIPT PAGES ARE NUMBERED THE SAME EVEN THOUGH THEY COVER DIFFERENTDATES.It was a very long and hard-fought case, involving many scientifictreatises and expert testimony. Both attorneys are to be commended fortheir excellent preparation and the zeal with which they tried the case._PRELIMINARY_Unless otherwise indicated, the word \”dosimeter\” [as used herein] refersto the Gen Rad 1954 type 2 instrument used in the April inspection ofthe Respondent’s jobsite. The dosimeter has an integrator that \”counts\”the sound waves that constitute noise; and it has a 5dB rate of exchangeas distinguished from a 3dB one. A \”decibel\” is roughly understood as aunit for expressing the relative intensity of sound. The integrator maybe \”slow\” [a time constant of 1 second] or \”fast\” [a time constant of1\/8th of a second]. The slow integrator is considered to be lessaccurate than the fast in following the quick noise…Tr. June 1147-1150.The jobsite was inspected in April of 1980. The machines cited punchpresses [#’s 2208, 2209, 2210 on the second floor annex, #0352 on the4th floor, and #2216 on the 2nd floor of the steel warehouse] and twolathes [#6040 and #3E 3018, both in the torsion department]. The soundlevels were obtained through the use of a dosimeter operated by or underthe supervision of OSHA Industrial Hygienist Anne Hart.In measuring sound for the purposes of Table G-16 of the standard at 29CFR 1910.95(a) – (b)(3), a dosimeter at slow response with a 5dB rate ofexchange is used because the standard mandates a \”slow\” response. Theevidence indicated that a different rate of exchange [e.g., 3dB] wouldnot qualify as a \”slow\” response; but, on the other hand, a differentrate of exchange might be more accurate for certain types of sound. Oneof the issues in the case was whether the 5dB rate of exchange woulddisclose the true level of sound if fluctuating or impulse [impact]noise were also present. \”Exchange rate\” is the relationship betweennoise level and duration. To illustrate: a 5dB exchange rate means thatthe sound level can be increased by 5dB with every halving of exposureduration.There are two sets of dates on which sound measurements were taken bythe Complainant: those in April, to which OSHC Compliance Officers Goydaand Hart testified; and those in September, to which sound expert Barrytestified. The witness Rockwell took sound measurements in February of1981; and the witnesses Jones, Kamperman, Holmer, Kundert, and Botsfordapparently did not participate in actual measurements of the citedmachines but testified as sound experts._IMPULSE NOISE_The case required considerable evidence of a highly technical natureinvolving sound level meters, dosimeters, 3dB and 5dB rates of exchange,various kinds of noise, etc. A basic issue 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 accuratelymeasured by the dosimeters used in the inspection? Should it have beenincluded or excluded in the dosimeter readout to determine compliancewith Table G-16?_TESTIMONYGoyda_The witness Goyda, who is an experienced and competent ComplianceOfficer, was a member of the OSHA inspection party. He monitored thedosimeter testing in April of the employee, Couture … Exh. C-1. I wasimpressed with his competence and honesty. I find that he accuratelyreported the readout registered by the dosimeter, as recorded in Exh. C-1.HartThe witness Hart, who is an experienced and competent IndustrialHygienist, was in charge of the April inspection of the jobsite. Shecalibrated the dosimeters used, directed the placing of dosimeters onemployees, and recorded or supervised the recording of their readouts… Tr. June 672 – 685. I was impressed with her competence and honesty.I find that she followed proper procedures in testing and that sheaccurately reported the readouts registered by the dosimeters, asrecorded in Exh. C1 – 5.She testified that the testing instrument was a Gen Rad 1954 Type 2dosimeter, slow response, A weighted…Tr. June 730, 733. She said thatimpulse noise is not supposed to be included in the dosimetermeasurement because the reading will be distorted and will inaccuratelyregister 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 Aprilinspection ranged from 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 ofimpulse noise are not supposed to be excluded; and that Table G-16 hasno relation to impulse noise and does not exclude it…Tr. March 512,513, June 913, 914, December 902. He emphatically stated that thefindings of Compliance Officer Hart were reliable with correctionfactors that would not change her conclusions; and that the typedosimeter used in her inspection was a suitable instrument for measuringnoise levels to determine OSHA compliance…Tr. June 952-958. Heconcluded that, even applying error factors, employees were stillexposed to excessive noise…Tr. December 984.However, Barry also testified that the dosimeter has been acontroversial instrument in recent years…Tr. March 517, 518. He saidthat dosimeters tend to register higher readings than actual noiselevels; and that, for the sounds typical here, the reading could behigher by 4 or 8 decibels…Tr. June 953, December 939, Exh. R-60. Healso said that the more impulse and the higher, the greater is thedosimeter’s error…Tr. June 1008. He testified that a dosimeter’sreadout might be inaccurate due to the slow response setting required bythe standard because, where there are both steady and impulse noises,the dosimeter distorts on the high side; and that the use of both fastand slow modes of response would be better testing procedure…Tr. June925-928, 933, December 909, 910, 917, 948. He suggested that, \”tomeasure it really properly, the standard would have to berewritten.\”…Tr. June 927. It had been his opinion [as he wrote in theOSHA Field Officer’s Manual] that, where both continuous and impulsenoise are present, the proper way to determine compliance with TableG-16 is to use the fast mode setting and record the reading between theimpulses…Tr. June 922, 923, 1015-1019. He had also authored an articlein which he stated that the standard at 29 CFR 1910.95 \”sets thepermissible exposure level for non-impulse noise.\”…Tr. June 920. Heacknowledged that he had said that Table G- 16 was intended primarilyfor non-impulse noise … Tr. December 904, 906, Exh. R-59, R-62.As concerns the 3dB and 5dB rates of exchange, he agreed that thereadout would differ depending on which was used, resulting in apossible dosimeter overstatement inaccuracy of 100 – 200 percent…Tr.June 934 – 937. He had also recommended a change in the dosimeter from a5dB exchange rate to the use of a 3dB one \”and making no differentiationbetween the type of noises. In other words, integrate all noise asnoise. And, use that for determining compliance or non-compliance.\”…Tr. June 943. While that suggestion could be explained asreferring to possible ambiguities in the standard, it could also beinterpreted as a belief that the standard does exclude some noise;otherwise, why the need to specify that all noise is included?Barry’s testimony also indicated that there was a discrepancy of severaldecibels between the slow and fast modes when he measured the machinesin question in his September visit at the Respondent’s jobsite…Tr.June 975 – 999, Exh. C-22. [On this point, the testimony is germane tothe difference between the slow and fast modes, if not on the merits ofthe citation itself.] He also testified that, in that same visit, hefound impulsive components of noise in all the cited machines except onelathe … Tr. June 913, 955._Rockwell_The expert Rockwell, who was called by the Respondent, waswell-qualified … Tr. June 1027 – 1031, 1131 – 1146, Exh. R-22. Hetestified that impulse noise [which is less than 1 per second and fewerthan 60 per minute] should be handled separately; and that it has beenOSHA policy since 1972 to exclude or edit out such noise in testing. Healso quoted an OSHA regional office and Chapter 4 of the OSHA FieldManual to the same effect…Tr. June 1150 – 1154, 1291. He said that thetype of dosimeter used in the April inspection erroneously read outseveral decibels higher because of impulse noise that should have beenexcluded…Tr. June 1159, 1160. He pointed out that recognizedauthorities took the same position… Tr. June 1161 – 1169, Exh. R-23.He also testified about tests he had conducted in the Respondent’s plantin February, 1981, using both slow and fast response dosimeters. Theslow 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 that the dosimeter overestimates exposure in \”this\” type ofenvironment [the Respondent’s jobsite] by 10 – 12 decibels over theactual exposure level… Tr. June 1195 – 1202. He said that the use of a5dB rate of exchange dosimeter resulted in inflated exposure readings,grossly overestimated the true noise, and was an inaccurate instrumentfor impulsive or rapidly fluctuating noise… Tr. June 1200 – 1202,1209, 1234, 1236. He specified errors of 10 – 15 decibels at eachlocation that he tested… Tr. June 1287, Exh. R-33. It was his opinionthat the instrument used could not substantiate the allegations, andthat impact noise levels should be measured only with an impact meter oran oscilloscope… Tr. June 1252, 1296, Exh. R- 35._Holmer_The expert Holmer, who was called by the Respondent, was well-qualified… Tr. June 1298 – 1310, 1479 – 1481, Exh. R-36. He testified thatimpulse noise should be eliminated in determining compliance with theG-16 table… Tr. June 1456, 1457. 1515. He said that, because of thedifference between the 3dB and the 5dB exchange rates, the Gen Rad 1954dosimeter used in the inspection would read higher than the actual noiselevel … Tr. June 1447, 1455, 1466, 1467. He said that such dosimetersinvariably overestimate signals fluctuating at the rate of 1 second orless; and that no dosimeter accurately records impulse noise in theTable G-16 sense because the standard requires a 5dB exchange rate…Tr. June 1441 – 1443, 1456. He also said that, although dosimeters readlower than theory would project, and a Gen Rad 1954 dosimer does notoverestimate as badly as an \”ideal\” dosimeter would, it stilloverestimates by a factor of 10 whereas an \”ideal.\” one wouldoverestimate by 12…Tr. June 1467, 1471._Kundert_The expert, Kundert, who was called by the Complainant, waswell-qualified. . . Tr. December 778 – 780, Exh. C-27, C-28. Hetestified that the Gen Rad 1954 dosimeter was designed specifically fortesting against the OSHA standard, is excellent for that purpose, andcan process short signals even though most dosimeters cannot. Althoughhe said it was designed to measure both continuous and impulse noise, heacknowledged that it cannot accurately measure very short impulses buttends to produce low readings. . . Tr. December 795 – 797, 871 – 874.Concerning the 3dB and 5dB rates of exchange, he testified that thedosimeter responds to impulsive sound as a 5dB instrument. . .Tr.December 863, 864. Concerning the question of whether Table G-16 isinterpreted to include or exclude impulse sound, he testified that theOSHA field guide says to exclude it as did ANSI S-1.25. He concludedthat, if impulse noise is to be excluded, the way to do it is by readingbetween the pulses, as the witness Rockwell did.. Tr. December 888 -890. He also said that the authorities cited in Exh. R-23 did notsupport Rockwell’s position but, on the contrary, disagreed with it. . .Tr. December 798 – 803. Recalled by the Complainant in rebuttal he saidthat, for the type of impulsive noise here, the sound level meter anddosimeter give almost identical results; and that his in-courtdemonstration with the dosimeter and sound level meter (measuring acontinuous sequence of impulses) produced the same results. . . Tr. 1982March 1728 – 1730, 1871 – 1876._Botsford_The well-qualified expert, Botsford, who was called by the Respondent,testified that the Department of Labor had recommended the exclusion ofimpact noise from Table G-16, and impact noise was not included in TableG-16. . . Tr. December 1038 – 1040, Exh. R-66.His testimony tended to establish that impact noise could not beaccurately measured by a sound level meter but should be measured by animpact meter againsta limit of 140 decibels; while continuous noise should be measuredagainst Table G-16, using a time- weighted instrument with a 5 decibelexchange rate and then reading between the impact peaks … Tr. December1076 – 1080. He said that the OSHA field manual recommends thisprocedure … Tr. December 1077, Exh. R-76._Hildyard_The Respondent seemed to place great reliance on the testimony of Dr.Hildyard to the effect that, although the advisory committee on OSHAstandards made a final recommendation of priority for administrative andengineering controls over personal protective devices, the committeemembers had actually voted not to accord priority to administrative andengineering controls over personal protective devices [such as earplugs] … Tr. March 565, 583. However, even if there had been noobjection to such testimony [and the Complainant did object to it], itwould be given no weight because it violates the parol evidence 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]. Theofficial record of the advisory committee on OSHA standards –which saidadministrative and engineering controls must be tried before personalprotective equipment — governs and not evidence tending to contradictit. Accordingly, I am limiting Dr. Hildyard’s testimony about thecommittee vote to whatever bearing it may have on the Respondent’s goodfaith._Jones_The expert Jones, who was called in rebuttal by the Complainant, was a awell-qualified industrial noise consultant. He testified that the soundlevel meter measures noise in the slow response better than the fast andthat there is no basis for editing out impulse noise…Tr. 1982 March1629 – 1639. However, he also stated that he agreed with the statementthat only steady noise is to be measured against Table G- 16 … Tr.1982 March 1695. Although his name also appeared on a documentapparently stating that Table G-16 values do not apply to impulse noise,he testified that such use was unauthorized and did not represent hisopinion. . . Tr. 1982 March 1651 – 1658, 1668 – 1670. Because of hissworn testimony to that effect, I do not place any reliability on thatdocument as far as it concerns any opinion by him.Jones also testified that Botsford had written an article in which hesaid impulse noise should be included in measurements of industrialnoise. . . Tr. 1982 March 1637, 1638._Kamperman_The expert Kamperman, who was called in rebuttal by the Complainant, wasa well-qualified industrial noise expert. He testified that thedosimeter is a very accurate instrument for measuring noise in anindustrial setting; that it always underestimates noise, and he hadfound no dosimeter that read high. . . Tr. 1982 March 1902, 1947, 1984.He also said that impulse noise should not be excluded from measurementsand that industry custom is to include it in computing noise forpurposes of Table G-16. . . Tr. 1982 March 1913 – 1917. He pointed outthat if impulse noises are edited out of a punching operation, therewould be no noise left because they are all impulsive signals. . . Tr.1982 March 1898, 1911. He said that his field testing of the 1954 GenRad dosimeter and a sound level meter produced approximately the sameresults, whether with or without impulse noise. . . Tr. 1982 March 1900,1901. He also said that the fast response is not as good as the slow indetermining noise per Table G-16. . . Tr. 1982 March 1902. He concludedthat he had never said that impulse noise should only be measured inaccordance with the 140dB peak, and had never said that impulse noiseshould be excluded from measurements. . . Tr. 1982 March 1984, 1985.However, when he was asked if he had said that \”it is not possible for asimple dosimeter to correctly compute the noise dose using a 5dBexchange rate for noises that vary in levels of less than 10 seconds,\”his answer included statements that \”problems come because of the OSHA5dB exchange rate. . . because the 5dB exchange rate violates basic lawsof physics\”. . . Tr. 1982 March 1960 – 1966. He also testified that thedosimeter \”has a hard time correctly measuring anything other thansteady random noise\” and that he is \”on the committee to revise thisstandard now to make dosimeters capable of correctly measuring impulsivesound.\”. . . Tr. 1982 March 1945. He also conceded that there is\”confusion\” over the measurement of impulsive noise in the industrialenvironment and that he had written an article stating that the standardonly addresses the measurement of continuous noise. . . Tr. 1982 March1948, 1949, Ex. R-110. He also testified that he had made a writtenstatement that, for impulsive noise, \”the dosimeter will always indicatea much higher dose that the sound level meter\” and that the disparitywould 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 aseminar that \”dosimeters used in the noise environment typically foundin metal fabricating facilities would read between 5 and 13dB too high,two to six times the expected noise dose relative to the OSHA 5 decibelexchange rate.\”. . . Tr. 1982 March 1953 – 1957, 1968-1970._DISCUSSION_With very minor differences, the experts all seemed to be in generalagreement that impulse noise is a sound of brief duration that occursless frequently than one a second and less than 60 a minute; andincludes such examples as hand clapping, dropping a book, firing arifle, the ram of a punch press, etc. It is also clear that all thecited machines [with the possible exception of the lathes] had impulsivecomponents in the noise. . . Tr. March 311, June 913, 921, 955, 956,1150, 1251.As indicated above in this decision, the experts differed in theiropinions on the accuracy of the measurements by the dosimeter. Rockwell,Holmer, and Botsford were firm in their conclusions that the dosimeterhad to be inaccurate because of the standard’s requirements that onlythe slow response may be used.Although Barry, Kundert, Jones and Kamperman concluded that thedosimeter readouts were accurate, they did make many concessions[specified above] that tended to establish there were distortions by thedosimeters used in the April inspection.In my opinion, the weight of the evidence clearly establishes that thedosimeters used were certain to overstate the employees’ exposure tonoise. I so find.The most troublesome question is whether impulse noise should beincluded or excluded from the dosimeter readout. The standard itselfmerely uses the words \”noise\” or \”sound\” except for the word\”continuous\” in paragraph (b)(2). Table G-16, with figures going only ashigh as 115, has a footnote: \”Exposure to impulsive or impact noiseshould not exceed 140dB peak sound pressure level\”. The standard at.95(b) 1 – 3 clearly mandates that sound levels be \”measured on the Ascale…at slow response\”. Table G-16 also specifies: \”Sound level dBAslow response\”. The Compliance Officer has no choice: the standard mustbe obeyed. The dilemma is that the standard mandates the use of the slowresponse mode of testing, but the evidence establishes beyond doubtthat, when impulsive noise is present, the slow response mode results inan inaccurate readout in excess of the true noise level.Even if the use of the slow response dosimeter results in distortedreadings, is the question of compliance to be based on such figures? Itis hard to believe that any branch of government would intend such aresult. Certainly a judicial forum could not condone any decision basedon inaccurate facts.The Complainant has the burden of proving that the Respondent’semployees were exposed to noise that exceeded the amounts specified inTable G-16. In my opinion, that calls for the Complainant to prove thatthere were actual and true noise levels in the amounts stated in TableG-16, and not merely readout figures provided by the mandated slowresponse dosimeter. I find that that is the Complainants burden of proofeven if it means that the Compliance Officer has to use two sets ofinstruments: one to comply with the mandate of the OSHA standard and asecond 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 technologyavailable [a need recognized by the Complainant’s very experiencedexpert, Barry… Tr. -June 927]. I strongly recommend such modificationbecause it is a scandalous situation when the various entities concernedwith safe working conditions — OSHA, the employer and employees, theComplainant and the Respondent, the attorneys, and the judicial forumitself — are all at the mercy of a system that practically guaranteescontroversy and uncertainty — because even the experts themselves arein almost total disagreement.If the present state of the law requires the use of instruments inaddition to any that are mandated by the standard, or calls for measuresto correct the readout figures, or makes the Complainant’s task moredifficult in any way, that is unfortunate; but the Complainant has theburden of proving its allegation.On the question of the accuracy of the slow response dosimeter whenimpulse or impact noise is present at the jobsite, there may be aconflict of testimony between the experts for the Complainant and theexperts for the Respondent. Assuming that all are equally honest andequally well-qualified [and I find them so to be] has the Complainantcarried his burden of proof?I find that the dosimeter’s accuracy has not been established; in fact,quite to the contrary, its inaccuracy was proven. The testimony of theRespondent’s experts to that effect was not shaken: and theComplainant’s experts [Barry, Jones, Kundert. and Kamperman] also madeseveral statements tending to the same conclusion. The inspectionofficer herself (Hart) also agreed that the dosimeter readout would beinaccurate when impulse noise was included. In that state of theevidence, I find that the dosimeter’s accuracy was not proven.On the question of whether to include or exclude impulse noise indetermining compliance with Table C-16: 1 find it should be excluded. Inthe first place, its inclusion was the basic cause of the dosimeter’sinaccuracy in the instant case. Secondly, I find that it was thecustomary practice for OSHA to exclude impulse noise in determining thepossibility of noise exceeding the figures in Table G-16. Theuncontradicted testimony of the expert Rockwell was that it has beenOSHA policy since 1972 to exclude such noise; and that Chapter 4 of theOSHA Field Manual is to the same effect…Tr. June 1150 – 1154, 1291.Hart’s testimony that impulse noise was not supposed to be includedcorroborates that conclusion.The Respondent has a constitutional right to be treated the same as anyother employer cited under the same standard. If the customary practiceof OSHA was to exclude such impulse noise, it should have been excludedin the instant case.Lastly, I find that any reasonable interpretation of Table G-16 leads tothe conclusion that impulse noise must be excluded. An analysis of thestandard can lead to no other conclusion. We begin with the assumptionthat it was intended to have a workable standard with accurate figuresin Table G-16 — and the standard should be interpreted to achieve thoseends. The standard clearly and explicitly states that the slow responsemode must be used — but that mode cannot accurately measure impulsenoise. The standard is so ambiguous about impulse noise that (in myopinion) reasonable persons would agree that two interpretations arepossible: (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 to exclude impulse noisesince that is the only interpretation that gives accurate figures in thereadout while still complying with the slow response mode, as mandatedby the standard. That is the only interpretation that gives a workablestandard with accurate figures in Table G-16.In the final analysis, the Complainant has not proven its case whetherimpulse noise is supposed to be included or excluded. If it should havebeen excluded, that was not done here; and if it should have beenincluded, it results in an inaccurate readout. In either event, thedosimeter used was not a reliable instrument on which to base the citation.The difference between the true sound level and the dosimeter’sinaccurate readout was not minor but amounted to at least severaldecibels. When the dosimeter’s readout ranged from 94 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 decibelsmight not be of any significance if the dosimeter readout were greatlyin excess of the figures in Table G-16, it becomes of paramountimportance when [as here] the readout ranges from 94 to 101.3 decibels.Where the noise is so excessive that an error of several decibels in thedosimeter is comparatively trivial, the inaccuracy becomes immaterial.For example, in the Frank Nutty case [5 OSHC 1727], where the recordednoise was 8 times more than that permitted in Table G-16, the ReviewCommission affirmed without review the decision of the AdministrativeLaw Judge that the Respondent had not complied with the noise standardconcerned. [Although the dosimeter was held to be adequate in that case,I find it easily distinguishable from the instant case]. Here, where thealleged excessive noise is comparatively slight and the dosimeter errorcomparatively great, it must be found that the Complainant has notproven excessive noise._Offers of Proof by the Complainant_Even assuming the admissibility of the evidence in the Complainant’svarious offers of proof, the quantity and quality of evidence castingdoubt on the reliability of the dosimeter is not diminished. If theproffered evidence had been admitted, it would not change my findings._Barry’s testimony of September inspection_In seeking to establish the admissibility of Barry’s testimonyconcerning his September, 1980, visit to the jobsite, the Complainantoffered the testimony of Compliance Officer Goyda that the conditionsprevailing at that time were similar to those of the official inspectionin April, 1980. The substance of Goyda’s direct examination was that themachines and the parts produced appeared to be the same on both datesand he observed no difference in them … Tr. March 29 – 31, 299 – 302.He took no measurements but described the parts in fairly general terms.He testified that he heard the noise emitted by the machines and it was\”the same\” on both dates … Tr. March 303.Cochran, the Respondent’s chief engineer, testified that the punchpresses used some 20 – 30 difference dies of varying weights, shapes,and thickness in producing 30 different components or parts. The weightsvary from 200 to one thousand pounds in sizes ranging from 8 x 10 inchesto 22 x 16 inches…Tr. March 103 – 108, 122. He said the manner inwhich the machines are operated changes every day; and the number ofparts and the length of the run vary with the particular job…Tr. March112 – 114, 171. That is also true of the machine’s number of strokes perminute…Tr. March 130, 149 – 151. He testified that the parts made bymachines 2208 – 2210 \”are all different\” and that the two parts made onApril 14th [the inspection date] were not like the two parts made onSeptember 15th [the date of Barry’s visit] but were \”4 absolutelydifferent parts\” . . . Tr. March 287. He explained that, although themachines themselves were identical, the operation was not \”because ithad a different tool in it and every tool runs differently. . . not thesame steel strip. . . a different width and fed a different length.\”. .. Tr. March 289. He also pointed out that there would be \”a widevariation\” in the noise because the gauge of the material is \”one factorthat is involved in producing noise when that die hits the stock\”. . .Tr. March 291, 292. He also testified that there were different soundson the lathe on some days. . . Tr. March 128.Bergeron, the Respondent’s assistant director of manufacturing,testified that dies may or may not be changed frequently because it is ajob shop. . . Tr. March 226 – 229.There was no contradiction of the testimony of Cochran and Bergeron onthe differences in dies, parts, strokes, and length of run. Moreover, Iwas favorably impressed by the candor and honesty of both witnesses; andboth certainly were in positions to know about the operations theydescribed.It was ruled that, on the basis of Goyda’s testimony that conditionsduring the April and September visits were similar, Barry’s testimonyabout his September visit was technically admissible; but both partieswere alerted to the fact that it would be given very little weight. . .Tr. March 303 – 307. My opinion was [and is] that in a matter assensitive and delicate as the determination of decibels of noise, moreis required than Goyda’s mere eye and ear observation of the appearanceand sound of machines and parts. The testimony of Barry about hisSeptember visit was admitted because, technically, Goyda’s testimonyfurnished a foundation of similarity. I have given it very little weightbecause, substantively, Cochran’s uncontradicted testimony establishedthat the difference in dies, parts, strokes, and lengths of run may wellhave resulted in different noise levels._REVIEW COMMISSION_In view of my findings concerning the inaccuracy of the dosimeter, Ihave not reached items 1(b) and 1(c) of Citation #1. I purposely havenot made alternative findings because it seems to me to be ofover-riding importance for the Review Commission to clear up theuncertainties arising out of the possible interpretations to which thestandard at 29 CFR 1910.95 is susceptible. I respectfully request thatmy decision be reviewed to that end.[As cited above, I am aware of the Frank Nutty case interpreting avirtually identical noise standard. However, I think that decision isnot only distinguishable in several aspects from the instant case but,of great importance, the point raised here was not discussed there.]_FINDINGS OF FACT_Having heard the testimony, observed the witnesses, and examined theexhibits, the following Findings of Fact are made:1. At all times concerned, the Respondent regularly received, handled orworked with goods which had moved across state lines.2. As concerns Items #1(a) of Citation #1, the dosimeter used in theinspection did not accurately 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 onthe A scale of a standard sound level meter at slow response._CONCLUSIONS OF LAW_1. At all times concerned, the Respondent was an employer engaged in abusiness affecting commerce within the meaning of the Act; and theOccupational Safety & Health Review Commission has jurisdiction over thesubject matter and the parties.2. The Complainant has not sustained the burden of proving theRespondent violated the standard at 29 CFR 1910.95(a)._ORDER_The whole record having been considered, it is ordered that Citation #1,and the penalty proposed therefor, be vacated.SO ORDERED.FOSTER FURCOLOJUDGE, OSHRCDated:June 28, 1982Boston, Massachusetts_APPENDIX __THE ACT__Section 654_ [section 5(a)(2)] Employer \”…shall comply withoccupational safety and health standards…\”_Section 666_ [section 17(b)] \”…employer who has received acitation for a serious violation … of this Act…shall be assessed acivil penalty of up to $1,000 for each suchviolation.\”_Section 666_ [section 17(k)] \”…a serious violation shall bedeemed to exist…if there is a substantial probability that death orserious physical harm could result … unlessthe employer did not, and could not…know of the presence of theviolation.\”THE STANDARDS29 CFR 1910.95(a) – (b)(3);? 1910.95 Occupational noise exposure.(a) Protection against the effects of noise exposure shall be providedwhen the sound levels exceed those shown in Table G-16 when measured onthe A scale of a standard sound level meter at slow response.(b)(1) When employees are subjected to sound exceeding those listed inTable G-16, feasible administrative or engineering controls shall beutilized. If such controls fail to reduce sound levels within the levelsof Table G-16, personal protective equipment shall be provided and usedto reduce sound levels within the levels of the table.(2) If the variations in noise level involve maxima at intervals of 1second 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 EXPUSURES[[1]]Duration per day, hours Sound level dBA slow response8………………………………………………………………………. 906…………………………………………………………………….. 924…………………………………………………………………….. 953…………………………………………………………………….. 972…………………………………………………………………… 1001-1\/2……………………………………………………………. 1021………………………………………………………………….. 1051\/2………………………………………………………………… 1101\/4 or less……………………………………………………… 115[[1]] When the daily noise exposure is composed of two or more periodsof noise exposure of different levels, their combined effect should beconsidered, rather than the individual effect of each. If the sum of thefollowing fractions: C1\/T + C2\/T2 Cn\/Tn exceeds unity, then, the mixedexposure should be considered to exceed the limit value. Cn indicatesthe total time of exposure at a specified noise level, and Tn indicatesthe total time of exposure permitted at that level.Exposure to impulsive or impact noise should not exceed 140 dB peaksound pressure level.FOOTNOTES:However, Ward noted that there was evidence in 1969 that impact noiseshould produce hearing loss, but that the addition of impulse noise to asteady noise reduced the effect of noise on hearing, and in other cases,enhanced the effect; in other cases there was no effect (II, p.379).[[1]] The standard is quoted in its entirety except for provisionsdealing with determining noise levels by octave band analysis, ameasurement technique not involved in this case.[[2]] This problem was noted early in the Commission’s experience withthe noise standard. See Weyerhaeuser Co., 74 OSAHRC 57\/F4, 2 BNA OSHC1152, 1153-54, 1974-75 CCH OSHD (P) 18,468, pp. 22,485-86 (No. 2116,1974) (lead opinion); Sun Shipbuilding & Drydock Co., 74 OSAHRC 61\/A2, 2BNA, OSHC 1181, 1182-83, CCH OSHD (P) 18,537 (No. 268, 1974) (lead andconcurring 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 pertinent part, 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 inherentlyinconsistent with the standard, which specifies that noise levels are tobe measured with a standard sound level meter. As we have explained, thedosimeter itself contains the circuitry of a standard sound level meter.It also contains other circuitry, but the other circuitry only performsautomatically calculations that would otherwise have to be donemanually. Thus, the dosimeter does precisely what the standard requires:measures sound levels with a standard sound level meter and performs thecalculations required by the cumulation formula. Whether it performsthose functions with sufficient accuracy is another question, which wewill address later. For now, we note only that the use of a dosimeter isconsistent with the standard, and reflect Collier-Keyworth’s contraryarguement Love Box Co., 76 OSAHRC 45\/05 4 BNA OSHC 1138, 1140 & n.21975-76 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 conservationamendment, \”which lists in detail the requirements a hearingconservation program must have. 46 Fed.Reg 4078 (Jan. 16, 1981), nowcodified at 29 C. F. R. ? 1910.95 (c)-(p). The hearing conservationstandard requires an employer to implement a hearing conservationprogram wherever employee noise exposures equal or exceed an eight hourtime-weighted average level of 85 dBA. 29 C. F. R. ?1910.95 (c) (1). Italso provides that, in determining whether this limit is exceeded,\”[a]ll continuous,intermittent and impulsive sound levels from 80 decibels to 130 decibelsshould be integrated into the noise measurements.\” 29 C. F. R. ? 1910.95(d) (2) (i). Thus, impulse noise is explicitly included in the hearingconservation standard. However, in promulgating the hearing conservationstandard, the Secretary did not purport to amend any provision of theold standard except subsection.(b) (2) The hearing conservation standardtherefore does not affect whether impulse noise is included under thestandard involved in this case, section 1910.95 (a)-(b) (2), whichrequire administrative and engineering noise controls and personalprotective equipment.[[5]] The Secretary’s expert witness, Dr. Burton Jaffe, testified thatnoise is a \”mechanical transfer of energy that really shakes the haircells and damage them\”.The manner in which this testimony is summarizedin the Secretary’s brief echoes what has become known as the \”equalenergy rule,\” a theory that equal amounts of noise energy are equallyharmful regardless of their form or duration. This theory was discussedat length in the preamble to the Secretary’s new hearing conservationstandard and expressly applied to impulse noise. See 46 Fed. Reg. at4096. Its application to impulse noise seems to have been upheld on thebasis of the rulemaking record compiled by OSHA to support the hearingconservation standard. See .Forging Industry Ass’n V. Secretary ofLabor, 773 F.2d 1436, 1451 (4th Cir. 1985) (en blanc).[[6]] The Secretary attempts on the basis of a witness’s testimony toreconcile Table G-16 with the 140 dB provision. We shall consider thistestimony after have completed our review of the text of the standard.See note 12 below.[[7]] When the original version of the standard was published by theLabor Department’s Bureau of Labor Standards under the Walsh-HealeyGovernment Contracts Act, 41 U. S.C. ? 35-45, this provision was set inthe same size type as other text and placed after the footnote to thetable. See 34 Fed. Reg. 7949 (1969) and 35 Fed. Reg. 1015 (1970)(corrections to standard). When the standard was adopted and reprintedunder the OSH Act in 1971, the Secretary did not support to–and was inany event not. empowered to–make any substantive change in it. Yet, the140 dB provision was then printed in the same small type as the footnoteto 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 fourLabor Department documents. The Labor Department’s own edition of OSHAstandards, I General Industry Standards and Interpretations 144 (OSHANo. 2077, .1984), prints the 140 dB impulse noise provision in, and inthe same size type as, the text. The 140 db provision is still part ofthe text of the original Walsh-Healey standard, 41 C.F.R. ? 50- 204.10.A Labor Department bulletin interpreting the Walsh-Healey standardcharacterized the provision as \”[t]he last sentence in paragraph (d) ofsection 50-204.10 . . . . \” Bureau of Labor Standards, U.S. Dept. ofLabor, Bulletin 334, Guidelines to the Department of Labor’sOccupational Noise Standards for Federal Supply Contracts, 4 (Dec. 4,1970). Finally, the corresponding provision in OSHA’s noise standard forthe construction industry– which adopted at about the same time as theoriginal 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 decisionrests on official notice of a material fact not appearing in theevidence of the record, a party is entitled, on timely request, to anopportunity to show the contrary.\”[[9]] The record contains various terms used to describe non-impulsivenoise, such as steady noise, continuous noise, steady-state noise, andintermittent noise. Except for intermittent noise, these terms suggestnoise that is constant in intensity over a relatively long period oftime. Intermittent noise varies in intensity, but not as rapidly asimpulse noise. For example, noise from a machine that is alternately onand off for several seconds at a time would be classified asintermittent noise.[[10]] Even in 1981, when the Secretary promulgated the hearingconservation amendment to the noise standard, there was a relativedearth of information on impulse noise. The Secretary noted: \”Incontrast to the studies of continuous noise mentioned above,dose-response relationships for impulse noise are not so easilydefined.\” 46 Fed. Reg. at 4096.ACGIH, \”Threshold Limit Values of Physical Agents\” (1969), reprinted inNational Safety Council, Fundamentals of Industrial Hygiene, AppendixA, pp.739-41 (1971). Collier-Keyworth introduced as Exhibit R-101 the1971 version of the ACGIH standard, which appears to be identical..[[12]] See also a chapter by Jones, \”Standards and Threshold LimitValues for Noise,\” in National Safety Council, Industrial Noise andHearing Conservation ch. 11, p. 309 (Olishifski & Harford eds.1975)(ACGIH limits \”incorporated in\” Walsh-Healy standard). That theACGIH standard substantially influenced the drafters of the Walsh-Healystandard leads the Secretary to rely heavily on testimony by Jones, whowas chairman of the ACGIH committee, that the table in the ACGIHstandard corresponding to Table G-16 \”would include anything that thesound level meter would respond to, be it a continuous[,] impact [or]impulsive noise.\” Jones further testified that the 140 dB impulse noiseprovision was intended to be an additional restriction on impulse noise,included because of the possibility that high intensity impulses couldbe harmful even if the limits in the table were not exceeded. TheSecretary states that Jones \”was, in effect, the author of the [140 dBimpulse noise] provision\” because the limits in the table adopted byJones’s ACGIH Committee were \”issued in virtually identical form by theDepartment of Labor as a standard under the Walsh- Healey Act. . . . .\”We are unable to credit this part of Jones’s testimony because the ACGIHstandard expressly stated that the exposure limits in its table do notapply to impulse noise. We therefore disagree with the argument in theSecretary’s brief that this part of Jones’s testimony is a reliableguide to the intent of the drafters of the Walsh-Healey standard.[[13]] The bulletin was revised on June 8, 1971, after the Walsh-Healeystandard was adopted under the OSH Act. The 1971 version was introducedinto evidence.[[14]] A passage written by Dr. Van Atta in Industrial Noise and HearingConservation, 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 continuousnoise exposure with a tradeoff of 5 dBA for each halving of the noiseexposure time. This includes a rough allowance for interruptions ofnoise exposure. Impact noises must be limited to less than 140 dB peaksound pressure level.It is important to note that this is a double requirement. For example,in a power-press department, it is necessary that both the instantaneouspeaks of the impact noises arising out of the operation of large pressesbe below 140 dB and that the continuous ambient background noise bebelow 90 dBA. [Emphasis added.][[15]] J Barry, \”Problems in Enforcement of the Occupational NoiseStandard,\” in Proceedings of Noise-Con 79, Machinery Noise Control, 11(Sullivan & Crocker eds. 1979). At the hearing in this case, Dr. Barryfirst testified that Table G-16 \”has no relation in impulse noise.\” Helater stated, however, that the standard did intend for impulse noise tobe included in dosage calculations.[[16]] The chapter is printed in Occup. Safety and Health Admin., U. S.Dep’t of Labor, VI OSHA No. 3058, Industrial HygieneField OperationsManual (1980), and in CCH Employ, S. & H. Guide, Edition No. 419 (May24, 1979).[[17]] At the hearing in this case, Dr. Barry stated that he recommendedthe use of fast response in this instruction to enable the inspector toanalyze the components of the noise to assist in evaluating thefeasibility 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 ismore accurate than slow response in displaying the true background noiselevel.) When the Secretary promulgated the hearing conservationamendment in 1981, he said that this IHFOM provision \”is clearly atvariance with the present standard and is being deleted.\” 46 Fed. Reg.4078, 4137 & n. 11 (Jan. 16, 1981). If, as Dr. Barry stated, the purposeof the provision was to assist inspectors to evaluate the feasibility ofengineering controls, there would have been no need for the Secretary todisavow it in this manner. In sum, we read the instruction as OSHAdid-to signify that impulse noise was not to be included in determiningwhether employee exposure exceeds Table G-16 levels.The Secretary also claims that the prescription of slow response in thestandard is inconsistent with any intent to exclude impulse noise fromTable G- 16. We are unconvinced of any logical inconsistency here. TheACGIH standard–from which the Secretary acknowledges the drafters ofthe Walsh- Healey standard drew heavily–both prescribed slow responseand excluded impulse noise. The same is true of the noise standardproposed by the Secretary in 1974. See 89 Fed. Red 37773, 37775 (Oct.24, 1974), proposing new section 1910.95 (c) (1) (ii).[[18]] Turner involved three presses in the same room. One stroked at arate of 27 per minute, and a second at 33 to 38 strokes per minute. 4BNA OSHC at 1556,1976-77 CCH OSHD at pp. 25,273-4. Thus, these twopresses alone would produce 60 or more noise impulses per minute, i.e.,continuous noise.[[19]] Collier-Keyworth occasionally alludes to this point in aconfusing fashion, speaking of dosimeters having an \”effective exchangerate of 3 decibels. Adosimeter set to employ a 3 decibel exchange rate would register thesame sound levels as would one set to employ a 5 decibel exchange rate.It would record a higher dosage, however, because the lower exchangerate shortens permissible duration’s. Yet, Collier-Keyworth does notargue that OSHA set its dosimeters here to employ a 3 decibel exchangerate. Instead, it maintains, based on the testimony of expert witnesses,that in impulsive noise environments dosimeters set to use a 5 decibelexchange rate and slow response will so overcount \”true noise levels\” asto approximate the results of employing a 3 decibel exchange rate withfast response. Collier-Keyworth’s argument rests on the assumption thatunder Table G-16 sound levels must be measured with a fast responseinstrument. We will discuss the validity of this assumption in the textbelow.[[20]] This effect is illustrated by Ex. R-26, which contains severalstrip chart recordings made by Rockwell, and by C-22L, a strip chartrecording made by Barry. One recording in Ex. R-26 shows noise patternsfor a power press operating at 100 strokes per minute. Because the peaksare less than one second apart, the noise is quasi-continuous. With thesound level meter set for fast response, which corresponds to inintegration time of an eighth of a second, the individual impulses arereadily visible and have peak intensities of 108-109 dBA superimposed ona background of about 99 dBA. On slow response, however, the noiseappears relatively continuous at a level of 104-105 dBA. Thus, comparedto fast response, the sound level meter at slow response reads highertroughs but lower peaks, that is, the individual impulses appear to beof longer duration but lower peak intensity.The reason for the difference is best explained by discussing thebehavior of the needle of a sound level meter: At slow response, theneedle does not have time to return to the continuous, background noiselevel before the next impulse comes along and caused it to swing backup. For example, in Ex. C-22L,the sound peaks are about two to threeseconds apart, and hence much farther apart than in Ex R-26. The noiselevels indicated by slow response are still different from that of fastresponse but not as different as in Ex. R-26, where noise peaks onlysix-tenths of a second apart gave the needle little time to swing backbefore the next impulse arrives.[[21]] Its argument is echoed in the observation of one dosimetermanufacturer that \”[i]t is the requirement of a slow response timeconstant in a dosimeter that causes a 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 minehealth regulation is arbitrary, capricious, or an abuse of discretion\”within the meaning of the Administrative Procedure Act).[[23]] The brief of the Chocolate Manufacturers Association, which theCommission permitted to appear on review as an amicus curiae, arguesthat dosimeters generally are unreliable. Attached to its brief arestudies by Dr. Paul Hess of Hershey Foods that argue in support of thisthesis and that criticize OSHA’s evaluation of Dr. Hess’s studies inOSHA’s preamble to revisions in 1983 of the hearing conservationstandard. The Chocolate Manufacturers Association also asks theCommission to take official notice of statements in OSHA’s IndustrialHygiene Technical Manual, p. B-47 (March 30, 1984)(\”the IHTM\”),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 Secretary of labor objects to the Chocolate ManufacturersAssociation’s brief, arguing that it improperly introduces evidence. Wedeferred ruling on this motion and on the taking of official notice ofthe IHTM material.We take official notice of the IHTM but we are not persuaded thataccepting its statements as true mandates a result here. The portion ofthe IHTM relied on by the Chocolate Manufacturers Association warns OSHAfield personnel that \”[s]hort-duration pulses with a low repetition ratemay be completely eliminated from the dosimeter readings simply becausethe averaging circuits in the instruments cannot respond fast enough tothe change in level.\” However, we understand this passage to mean thatdosimeters sometimes undercount the noise level when certain impulsesare present; moreover, if \”low repetition rate\” refers to impulses morethan one second apart, then the supposed inaccuracy is irrelevantbecause we hold that such impulses may not be counted at all. Anotherpassage relied on by the amicus states that \”[c]onversely, pulses with ahigher repetition rate may be overestimated by the dosimeter because theaveraging circuits will build up to the high level but will not havetime to drop back down between the pulses.\” We are puzzled by thispassage, for it could be read to complain of the slow response modemandated by OSHA’s own standard. In any event,if it refers to impulsesmore than one second apart, it is irrelevant for the reasons we havealready stated. And if it refers to impulses less than one second apart,then it is also irrelevant because under subsection (b)(2), thedosimeter does not have to drop back down between impulses at all. Thus,we are not persuaded that the IHTM requires rejection of the dosimeterreadings here.On the other hand, we grant the Secretary’s motion to strike thoseportions of the Chocolate Manufacturers Association brief thatintroduces the studies of Dr. Hess. We decline to take official noticeof this material. The material attached by the amicus to its reviewbrief is largely evidentiary, consisting of papers and studies by Dr.Hess challenging the accuracy of dosimeters generally. As the Secretaryargues, however, the author of this material has not been subjectedcross- examination and the Secretary’s counsel has had no opportunity toevaluate, impeach or rebut his studies. Thus, if this new material wereto 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. In these circumstances, we adhere to our rule against theadmission of evidentiary materials in review briefs. E.g., AnoplateCorp., 86 OSAHRC , 12 BNA OSHC 1628, 1683, n.6, 1986 CCH OSHD (P)27,519, pp. 35,681-2 n. 6 (No. 80-4109, 1986).[[24]] Collier-Keyworth points out that in cross-examination Harttestified she did not know the \”strokes per minute\” for the presses andsuggests that this casts a doubt on her testimony that she measured thespeed of the presses. However, Hart’s testimony that she did not knowthe \”strokes per minute\” does not contradict her unequivocal testimonythat she timed the presses and found that the time between strokes wasless than one second. Under the standard, the noise is deemed continuousif the time between strokes is less than one second and, once this isknown, it is not necessary to determine the exact time between strokesor the exact stroke rate.[[25]] The strip chart recordings of noise levels made by Barry andRockwell show noise levels in the vicinity of the presses ranging from95 to 105 dBA. Although these measurements were made on different daysthan Hart’s, they lend credence to Hart’s measurements indicating thatthe sound levels near the presses were typically in this range.[[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 conservation amendment)(entry for 91.9 dBAcorresponds to dose of 130 percent).[[27]] The error factors for Type 2 sound level meters are found in ANSIS1.4-1971, \”Specification for Sound Level Meters,\” at 11, Table 3. Someof the information in that table, including the error factor at 8000hertz, was included in the papers Dr. Barry presented at PurdueUniversity, which appears in the record as Exhibit R-62. OSHA appliedthat information to Type 2 dosimeters in its IHTM. See Table 1 of FieldService Memorandum 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 thestandard excluded impulse noise, Judge Furcolo did not make findings onthe merits. Normally, we would remand to him for 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 administrativecontrols for these machines were feasible.[[30]] Barry believed that erecting acoustical enclosures entirelyaround the presses would be impractical due to space limitations andproduction demands.[[31]] The dies for each press were changed an average of about once perday. Some of Collier- Keyworth’s dies weighed as much as 1,000 poundsand had to be changed using a chain hoist. When the chain hoist wasused, the die could swing into the enclosure and damage it. Barrytestified that this could be avoided if the operator was careful. Holmertestified, however, that another company experienced severe damage tosimilar enclosures after 14 to 20 die changes. Holmer also estimatedthat enclosures would add 20 to 40 minutes to the time required for adie change.[[32]] The highest dosimeter reading the Secretary obtained for any ofthe press operators was 305%. This is equivalent to an eight-hourtime-weighted average exposure of 98 dBA. See section 1910.95, AppendixA, Table A-1.[[33]] Most of the studies relied on in the paper were performed withgunshot noise, but the authors considered the information sufficientlygeneral to be extended to other types of impulse noise.[[34]] Threshold shift is a measure of hearing loss. A person’s hearingthreshold is the lowest sound level in decibels that person can detect.If the person suffers hearing loss, his threshold increases, i.e., hecan no longer hear decibel levels as low as he previously could. Thenumber of decibels by which his threshold increases is his thresholdshift. A permanent hearing loss is referred to as a permanent thresholdshift or PTS. Short exposures to high noise levels can cause a temporaryhearing loss, or temporary threshold shift. When a person suffers atemporary threshold shift, his hearing recovers after the exposure tohigh noise levels ceases. However, repeated exposures sufficient tocause temporary threshold shifts can lead to a permanent thresholdshift. Therefore, to test whether noise exposures give rise to thepossibility of permanent hearing loss, scientists measure temporarythreshold shifts in exposed individuals. If an exposure producesmeasurable temporary threshold shifts, repetitive exposures of the samemagnitude will eventually cause permanent threshold shifts. See 46 Fed.Reg. 4078, 4080 (1981) (preamble to hearing conservation amendment).”