“SECRETARY OF LABOR.Complainant.v.PRIDE OIL WELL SERVICE,Respondent.OSHRC Docket No. 87-0692\/DECISION \/Before:FOULKE, Chairman: WISEMAN and MONTOYA, Commissioners.BY THE COMMISSION:As a result of an accident investigation and inspection by theOccupational Safety and Health Administration (\”OSHA\”), Pride Oil WellService (\”Pride\”) was charged with serious violations of standardspromulgated under the Occupational Safety and Health Act of 1970, 29U.S.C. ?? 651-678 (\”the Act\”), because it failed to provide: (1)respiratory protection to employees involved in monitoring the contentsof a mobile storage tank from an opening in its top; or (2) a signwarning of potential hazards or unsafe practices involving the tank. Atissue is whether Review Commission Administrative Law Judge E. CarterBotkin erred in concluding that Pride committed these alleged violations.I. \/Background\/Pride is an oil well service company with its principal office locatedin Houston, Texas. Pride and several other subcontractors had crewsworking to restore a well in Angleton, Texas, to be operational again. Tommy Mostyn, a drilling consultant, had been hired by the owner of thewell to oversee the entire project. Mostyn, in turn, gave directions toGeorge Cantu, Pride’s rig supervisor, or \”tool pusher,\” who wasresponsible for supervising Pride’s crew.As part of the process to \”recomplete\” the well, another subcontractorused tubing to insert liquid nitrogen, under pressure, into the well toforce diesel oil, water, and other materials from the well bore and intoa 500-gallon \”frac tank,\” or mobile storage tank (\”the tank\”). Duringthis process, liquid nitrogen changed into nitrogen vapor or gas, anodorless asphyxiant, that combines with the vapors or gases from thediesel oil and other hydrocarbons present in the tank to form a gaseousmixture that is heavier than air. This mixture then displaces the oxygenin the tank, forcing it out through the tank’s vent holes.In order to determine how deeply to drill, Mostyn needed to know thelevel of the \”returns,\” or the fluid that was coming out of the well andinto the tank. He ordered Cantu to have an employee go up onto the topof the tank to monitor the flow of the \”returns\” from an opening there,but Cantu protested. Cantu testified that he told Mostyn that it wasunnecessary to have employees on top of the tank because he \”had alreadyrigged up a way to get a sample off the needle valve\” which wasobservable from the ground. When Mostyn persisted, Cantu relented andassigned Mario Perez, a Pride floor hand, to go up on the tank toobserve the level of the \”returns.\”The opening in the top of the tank through which the level of the\”returns\” could be observed measured 18-1\/2 inches square, with ahatchway cover that had been left open for monitoring purposes. Nearby,there was a small, circular hole that measured three inches in diameter.There was a ladder on the exterior of the Tank leading to its top, butno ladder leading down into the interior of the tank. Perez testifiedthat he had to kneel and look down into the hatchway opening, sometimessticking his head through the opening, in order to perform hisassignment to check the flow of the liquid. [[1]]To relieve Perez for lunch, Cantu assigned Rodrigo Reyes, another Pridefloor hand, to go up on the tank. When Perez came down, Cantu wastalking with another Pride employee, Arnoldo Zamora. Cantu testifiedthat Perez asked him what was coming out of the well because it was\”making [him] real dizzy\” and \”making [his] head hurt.\” Cantu respondedthat, as far as he knew, diesel, nitrogen, and some gas were coming outof the well. When Perez told Cantu that he was not going back up, Cantusaid that was \”[f]ine\” and went for a coffee break. Cantu testified thatwhen he left for that break, he saw Reyes sitting within one to two feetof the hatchway opening. [[2]]About five minutes after Cantu had gone on his break, Mostyn went intothe trailer house and told Cantu that one of his men had fallen into thetank. Cantu climbed on top of the tank, after having learned that one ofthe older Pride employees had already responded to the accident byclosing the wing valve at the well head. When he called for Zamora, whomhe had spoken to before taking the break, another employee told Cantuthat Zamora also had gone into the tank, apparently for a rescueattempt. When Cantu observed through the opening a body floating thatstill had hand movement, he took a deep breath and entered the tank.However, this rescue attempt was unsuccessful. Cantu himself becamedizzy and weak in his knees and then collapsed. Not until an air hosewas thrown down to him was Cantu able to breathe sufficiently to climbout of the tank.The autopsy reports stated that both Reyes and Zamora had died as aresult of: \”Asphyxia due to drowning (diesel and H2O).\” Also noted inReyes’ autopsy report was the presence of \”[m]ultiple abrasions andcontusions\” on the upper front of the head. The judge found that these\”abrasions and contusions\” were consistent with Reyes having lostconsciousness and then falling into the tank. The opinion of theforensic pathologist, who performed the autopsies, was that eachemployee died \”as a result of asphyxia due to drowning, accidental,while at work.\”It is undisputed that Pride did not provide any respiratory protectionto these employees, nor was there any sign posted to caution employeesregarding potential hazards or unsafe practices involving the contentsof the tank. When asked if the employees had been \”trained in any wayabout oxygen-deficient atmospheres,\” Pride’s supervisor Cantu testifiedthat he personally had not been. He further testified that there was noequipment at the worksite for testing the oxygen level in the tank.Moreover, the OSHA compliance officer who conducted the investigationand the inspection testified that she concluded that Pride employees hadnot been given any training in oxygen deficiency, and that \”[s]ome ofthem didn’t even know what it was.\”Following the OSHA investigation and inspection, Pride was issued acitation alleging, as amended in the complaint, serious violations ofthe respiratory protection standard at 29 C.F.R. ? 1910.134(a)(2) andthe caution sign standard at 29 C.F.R. ? 1910.145(c)(2)(i). [[3]] OnApril 2, 1990, this case was directed for review on issues relating tothe judge’s affirmance of these two citation items.II. Respiratory ProtectionCitation no. 1, item 2, as amended, alleges that Pride committed aserious violation of 29 C.F.R. ? 1910.134(a)(2) [[4]] by failing toprovide respiratory protection to employees involved in monitoring the\”returns,\” as well as those employees who had attempted rescue. In orderto establish a violation of a specific standard, the Secretary mustprove by a preponderance of the evidence that: the standard applies tothe cited condition; the employer failed to meet the terms of thestandard; its employees had access to the violative condition; and theemployer either knew or could have known of the condition with theexercise of reasonable diligence. E.g., Astra Pharmaceutical Prods., 9BNA OSHC 2126, 2129, 1981 CCH OSHD 25,578, pp.31,899-900(No. 78-6247,1981), aff’d in pertinent part, 681 F.2d 69 (1st Cir.1982).Pride does not dispute that it failed to provide respirators to itsemployees, and that its employees had access to the cited condition.However, Pride contends that (1) to prove that respiratory protectionwas \”necessary to protect the health of the employee,\” as the citedstandard requires, the Secretary must show that the cited conditioninvolved \”contaminated\” air causing \”occupational diseases,\” as thepreceding subsection of the respiratory protection standard requires;(2) the standard is unenforceably vague in light of industry practice;(3) it had no knowledge of the violative condition; and (4) theviolation was the result of unpreventable employee misconduct.A. Whether the secretary Proved the Requisite Health Hazard1.What Health Hazard Must Be EstablishedSection 1910.134(a)(2) requires the provision of respirators \”when suchequipment is necessary to protect the health of the employee.\” Prideargues that, in order to prove a violation of section 1910.134(a)(2),the Secretary must show, as the preceding subsection at 29 C.F.R. ?1910.134(a)(1) [[5 ]] requires, that the cited condition involved\”occupational diseases\” caused by breathing \”contaminated\” air.According to Pride, she has not met that burden in this case. Prideargues that, because subsection (a)(1) ends by referring to \”thefollowing requirements,\” it is necessary to read it together withsubsection (a)(2) to learn what those requirements are. Pride contendsthat the Secretary failed to prove that Pride’s employees were exposedto an \”occupational disease\” caused by \”air contaminated withharmful,dusts, fogs, fumes, mists, gases, smokes, sprays, or vapors.\”The judge correctly ruled below that the requirements of subsection(a)(2) are to be read independently of subsection (a)(1).In Brock v CityOil Well Service Co. (\”City\”), 795 F.2d 507 (5th Cir. 1986), theemployer had been cited for violating both sections 1910.134(a)(1) and(2) for failing to provide respirators to protect the health ofemployees on top of a \”frac tank\” against exposure to hydrogen sulfidegas (\”H2S\”), \”a deadly byproduct of oil and gas production.\” 795 F.2d at508 & n.1. The Fifth Circuit, to which this case can be appealed, [[6]]rejected City’s argument that subsection (a)(1) required the Secretaryto prove that engineering controls were not feasible before arequirement for respiratory protection arose under subsection (a)(2).More specifically, the court also rejected the argument that thelanguage in subsection (a)(1) concerning the feasibility of engineeringcontrols must be read into (a)(2), declaring that \”the requirements of(a)(2) … are independent of and can form the basis of a violationdistinct from (a)(1).\” 795 F.2d at 510 n. 5. Cf.Snyder Well Servicing,Inc., 10 BNA OSHC 1371, 1375-76, 1982 CCH OSHD ? 25,943, pp. 32,510-11(No. 77-1334, 1982) (implicit rejection of employer’s argument based onsimilar facts).Therefore,based on the decisions noted above, we reject Pride’s argumentthat, before she can establish a violation of subsection (a)(2), theSecretary must show that Pride’s employees were exposed to an\”occupational disease\” caused by \”contaminated\” air, as discussed insubsection (a)(1).2. Whether the Secretary Has proven that Respirators Were \”Necessary toprotect the Health of the Employee\”The next issue for consideration is whether the judge erred in findingthat the Secretary established that respirators were \”necessary toprotect the health of the employee.\” In addressing the question of theneed for respirators, the judge particularly relied on the testimony ofthe Secretary’s Regional Industrial Hygienist Richard Wingo. Wingotestified that nitrogen displaces oxygen in a confined space and thatwhen the oxygen falls below 19.5% of the air’s content, the results canbe: impairment of vision and mental capabilities; dizziness andfainting; unconsciousness; and even death. The judge found Wingo to he a\”well-qualified individual\” and an \”impressive and highly crediblewitness.\” The judge stated that, when he viewed Wingo’s testimony as awhole, \”it is obvious that he considered the nitrogen, diesel and otherelements to be a contaminant of the air in this confined space, causingan oxygen deficient atmosphere. Without question, I hold that view.\”(emphasis added; transcript reference deleted). The judge’s finding thatthe atmosphere in the tank was oxygen-defficient is supported by hisdetermination, which is not challenged by Pride, that \”the credibleevidence establishes that he [Reyes] fell and did not voluntarily enterthe tank\”. The judge concluded that the employees assigned to monitorthe returns from atop the tank, as well as those attempting to rescue,were exposed to \”a hazard to the health (asphyxiation or drowning).\”Pride has not introduced any evidence to dispute Wingo’s testimonyconcerning the likelihood that the tank had an oxygen-deficientatmosphere on the day in question.[[7]] Based on that testimony by Wingoand the weight of the evidence establishing that Reyes did notvoluntarily go into the tank, we conclude that Pride’s employees wereexposed to the hazard of asphyxiation, which resulted in their drowning.We therefore conclude that the judge did not err in finding that, inthis case, respirators were \”necessary to protect the health of theemployee.\”B.Whether the standard is Unenforceably VaguePride argues, as it did below, that section 1910.134(a)(2) isunenforceably vague because the standard’s requirement for respiratoryprotective equipment is so broadly worded that it fails to providenotice sufficiently specific to satisfy due process concerns.When faced with such claims in relation to broadly-worded standards, thecourts and the Commission have considered whether a reasonably prudentemployer, familiar with the circumstances,would recognize a hazardwarranting the same protection in the cited standard. See Bratton Corp.,14 BNA OSHC 1893, 1898-98,1990 CCH OSHD 29,152, p. 38,993 (No. 83-132,1990) and cases cited therein. As Pride notes, for the generally-worded, personal protection standards at 29 C.F.R. ?? 1910.132(a) and1926.28(a), the Fifth Circuit has determined that \”industry custom andpractice will generally establish the conduct of the reasonably prudentemployer ……\” Cotter & Co. v. OSHRC, 598 F.2d 911, 913 (5th Cir.1979). Accord S & H Riggers & Erectors, Inc. v OSHRC, 659 F.2d 1273,1285 (5th Cir. 198 1); Power Plant Div., Brown & Root, Inc. v. OSHRC,590 F.2d 1363, 1365 (5th Cir. 1979); B & B Insulation, Inc. v. OSHRC,583 F.2d 1364, 1370-71 (5th Cir. 1978).Pride notes that its supervisor Cantu and safety coordinator JimmyHarville both testified that the common practice in the well-servicingindustry is not to provide respirators, but rather to depend on the welloperator or offer to provide respirators, as well as information aboutany dangerous condition concerning the well. This is because the wellowners and operators have records on the well that are not available towell- servicing companies. Pride contends that, as it was not industrycustom to provide respirators, section 1910.134(a)(2) is unenforceablyvague.In his decision, the judge rejected Pride’s argument, relying on theFifth Circuit’s decision in City, supra, where the court squarelyrejected City’s argument that the industry practice test that the FifthCircuit itself had applied with regard to other standards (such assections 1910.132(a) and 1926.28(a)) is appropriate for section1910.134(a). The court stated that the employer’s reliance on the sameline of cases that Pride cites was \”misplaced\” because:The regulation here [section 1910.134(a)] is precise. In City’s case, itconcerns only one hazard and two remedies. The hazard is hydrogensulfide . . . ; the two remedies are effective engineering controls andrespirators, the requirements for the selection, use, and maintenance ofwhich are set out in detail. See generaIly 29 C.F.R. ? 1910.134.795 F.2d at 511.The court noted that City’s emphasis on the well-servicing industry’sreliance on the well operator or owner to provide respirators was notonly inappropriate under the cited standard, but also an improperattempt to \”use industry custom to shift its statutory responsibilityfor the health and safety of its employees to third parties.\” Id.Based on the Fifth Circuit’s decision in City, we find that the judgedid not err in his ruling on this issue. Furthermore, we note that theCommission has issued a decision that relies on City and holds thatsection 1910.134(a)(2) is not vague, and therefore the reasonableemployer test is not needed to interpret and apply the standard. PowerFuels, Inc., 14 BNA OSHC 2209, 2213, 1991 CCH OSHD ? 29,304, p. 39,346(No. 85-166, 1991).We reject Pride’s argument that the Fifth Circuit and Commissiondecisions are factually distinguishable from this case because thosedecisions involve the \”well-known\” hazard of H2S, instead of nitrogen.Section 1910.134(a)(2) does not make any reference to how well-known anyspecific substance or condition must be in order to require respirators.It states only that respirators must be provided where they are\”necessary to protect the health of the employee.\” Nevertheless, we notethat, as shown by Table 1 in the American National Standard, ANSIZ88.2-1969, Practices for Respiratory Protection, section 4 (1969),[[8]]oxygen deficiency in tanks or other confined spaces resulting fromnitrogen or another simple asphyxiant diluting the oxygen in the air isa well-recognized respiratory hazard.Therefore, based on our own precedent and the decision in City by theFifth Circuit, to which this case can be appealed, we reject Pride’sarguments here and find, as the judge did, that section 1910.134(a)(2)is not unenforceably vague.C. Whether Pride Had Knowledge of the Violative Condition1. Whether the Secretary Proved KnowledgeAs noted above, to prove a violation the Secretary must show that thecited employer had knowledge of the violative condition. She can satisfythis burden by establishing that the employer either knew, or, with theexercise of reasonable diligence, could have known of the presence ofthe violative condition. E.g., Tampa Shipyards, Inc., 15 BNA OSHC 1533,1537, 1992 CCH OSHD ? 29,617, p. 40,100 (No. 86-360. 1992); GaryConcrete Prods., Inc., 15 BNA OSHC 1051, 1052, 1991 CCH OSHD ? 29,344,p. 39,449 (No. 86-1087, 1991). The actual or constructive knowledge ofthe employer’s foreman or supervisor can be imputed to the employer. Id.The judge concluded that the Secretary made a pirma facie showingPride’s supervisor Cantu actually knew, or could have known, with theexercise of reasonable diligence, of the cited condition. He furtherfound that Cantu’s actual or constructive knowledge that respiratoryequipment was necessary to protect the health of the employee wasimputable to Pride.We find no error in the judge’s ruling that a prima facie showing ofPride’s knowledge has been established based on the record. As the judgenoted, Cantu’s actual knowledge of the conditions at the worksite thatled to the violations cited here was established by Cantu’s testimonythat Perez complained to him that what was coming out of the tank wasmaking [him] real dizzy\” and \”making [his] head hurt,\” and that he wouldnot go back up on the tank. Cantu was given further notice of the hazardwhen he learned that Reyes and Zamora were in peril. Nevertheless, Cantuattempted to rescue them before almost being overcome himself.The Secretary also proved that Pride had constructive knowledge becauseits supervisor Cantu could have discovered and eliminated the hazardwith the exercise of reasonable diligence. Reasonable diligence involvesseveral factors, including an employer’s \”obligation to inspect the workarea, to anticipate hazards to which employees may be exposed, and totake measures to prevent the occurrence.\” Frank Swidzinski Co., 9 BNAOSHC 1230, 1233, 1981 CCH OSHD 25,129, p. 31,032 (No. 76-4627, 1981).Although Cantu personally objected to Mostyn’s instructions to put anemployee on the tank, in light of the on-ground sampling method thatCantu had put in place, Cantu did not raise the matter at that time withhis supervisors at Pride. However, he testified that he had previouslyraised with them other orders from Mostyn. Moreover, Cantu admittedthat, even though he could not have done anything that Mostyn had notapproved, the safety of Pride’s crew was his own responsibility.As a crew supervisor, Cantu had a general responsibility to acquainthimself with the contents of the tank and the hazards that they mightpose to Pride employees. This obligation was heightened when Perezcomplained to him that what was coming out of the well was \”making [him]real dizzy\” and \”making [his] head hurt.\” In light of Perez’s complaintand the considerable likelihood of serious injury, Cantu could have atleast told Mostyn or his supervisor at Pride about Perez’s complaint andmade inquiries. See Getty Oil Co. v. OSHRC, 530 F.2d 1143, 1146 (5thCir. 1976) (reasonable diligence includes \”simple expediency of …making inquiry\”).Evidence in the record indicates that Cantu knew that nitrogen was beingused to force the material out of the well, and that nitrogen and dieselwere present in the tank. He said as much to Perez in response toPerez’s question following his complaint of dizziness and a headache.Furthermore, Cantu had some understanding that the operations on the dayof the accident were not typical. He testified that, based on hisfifteen years of experience in the oil well business, the contents ofthe well were not ordinarily put into an enclosed \”frac tank\” whennitrogen was being used. Cantu stated that when the operation involvesjetting nitrogen, the returns from the well are usually directed into an\”open earth pit\” or an \”open 200 barrel, tank.\” Arguably, a reasonablydiligent employer who was aware of this departure from normal procedureswould have questioned Mostyn or the well operator after Perezcomplained, if not before.Other factors indicative of reasonable diligence include adequatesupervision of employees, and the formulation and implementation ofadequate training programs and work rules to ensure that work is safe.Gary Concrete, 15 BNA OSHC at 1054-55, 1991 CCH OSHD at p. 39,451-52;see Towne Constr Co., 12 BNA OSHC 2185, 2190- 91, 1986-87 CCH OSHD ?27,760. pp. 36,312-13 (No. 83-1262, 1986), aff’d, 847 F.2d 1187 (6thCir. 1988). Although the record here shows instances where Cantu’ssupervision of his crew was arguably not adequate, the real problem wasthat Pride had failed to formulate and implement adequate work rules andtraining programs to ensure that Cantu had been informed of theappropriate safety considerations. Cantu testified that he had not beentrained in what do in oxygen-deficient atmospheres, and, based on theevidence concerning the accident day, apparently neither had any of hiscrew. However, he and his crew had been made aware of the dangers of H2Sand trained in how to respond to it, including how to use masks andoxygen tanks. Cantu’s lack of understanding of the oxygen deficiency inthe tank was most dramatically demonstrated when he went in the tankhimself in the rescue attempt.Based on the considerations above, we conclude, as the judge did, thatthe Secretary has made her prima facie showing that Pride had knowledgeof the violative condition.2. Whether Pride Rebutted the Showing of KnowledgeTo rebut prima facie proof that the knowledge of a supervisor should beimputed to it, the cited employer must offer evidence that it had:established work rules designed to prevent the violation; adequatelycommunicated those work rules to its employees (including supervisors);taken reasonable steps to discover violations of those work rules; andeffectively enforced those work rules when they were violated. E.g.,Tampa Shipyards, Inc., 15 BNA OSHC at 1538,1992 CCH OSHD at p. 40,100;A.P. O’Horo Co., 14 BNA OSHC 2004, 2007-08, 1991 CCH OSHD ? 29,223, p.39,129 (No. 85-369, 1991).There is no evidence that Pride had a work rule specifically addressingthe hazards of oxygen-deficient atmospheres. Rather, Pride relies on itswork rule for confined space entry under the theory that an employeesticking his head through the opening in the top of the tank to observethe level of the \”returns\” would be violating that rule, as would anemployee who entered the tank for rescue purposes. Pride contends thatwhatever knowledge Cantu might have had of the violative conditioncannot be imputed to it because it had implemented, communicated, andenforced the following \”basic safety rule\” set forth in its \”EmployeeBenefit Summary and Safety Guide:\”Confined Spaces — Employees are not authorized to enter any confinedspaces for any reason. Confined spaces are defined as frac tanks,storage tanks, tank hatches or any other spaces not fully ventilated tofresh air.We note that supervisor Cantu’s voluntary entry into the tank in hisattempt to rescue his crew members was in clear violation of this workrule. Where a supervisor engages in misconduct and is exposed to thehazardous condition, that is strong evidence of lax enforcement of theemployer’s safety program. E.g., Brock v. L.E. Myers Co., 818 F.2d 1270,1277 (6th Cir. 1987), cert. denied, 484 U.S. 989 (1987); Baytown Constr.Co., 15 BNA OSHC 1705, 1710, 1992 CCH OSHD ? 29,741, p. 40,414 (No.88-2912-S, 1992).Pride could have prevented this conduct by sufficiently training Cantuin the hazards of, and procedures necessary for, oxygen-deficientatmospheres. However, Cantu testified that Pride failed to provide thistype of training, and Pride presented no evidence that it had given suchtraining. See Daniel Constr Co., 10 BNA OSHC 1549,1552, 1982 CCH OSHD ?26,027, p. 32,672 (No. 16265, 1982). As Cantu’s testimony indicated,nitrogen is not uncommonly used in the well-servicing industry, and itsdiluting effect on oxygen should have been made known to all employees,especially supervisors.The Act places final responsibility for compliance with its requirementson the employer. E.g., City, 795 F.2d at 511, quoting section 5(a)(2) ofthe Act, 29 U.S.C. ? 654(a)(2) (\”[e]ach employer …shall comply\” withOSHA standards) (court’s emphasis). An employer who has failed toaddress a hazard by implementing and enforcing an effective work rulecannot shift to its employees the responsibility for assuring safeworking procedures. See, e.g., Stuttgart Machine Works, Inc., 9 BNA OSHC1366, 1369, 1981 CCH OSHD ? 25,216, p. 31,142 (No. 77-3021, 1981). Anemployer \”cannot fail to properly train and supervise its employees andthen hide behind its lack of knowledge of their dangerous workingpractices.\” Danco Constr. Co. v. OSHRC, 586 F.2d 1243, 1247 (8th Cir.1978). Here, Pride failed to adequately train its supervisor in therespiratory hazard of, and the safety procedures for, oxygen deficiency,to which he and some of his crew were exposed. We therefore concludethat Pride has failed to rebut the Secretary’s showing, and we imputeCantu’s knowledge to Pride.D. Whether the Conduct of Pride’s Employees Was UnpreventablePride further asserts that it was not in violation of the standardbecause it did all that it could reasonably have done to prevent theviolation. To prove the affirmative defense of unpreventable employeemisconduct, the employer must show that it had established a work ruledesigned to prevent the violation, adequately communicated those workrules to its employees (including supervisors); taken reasonable stepsto discover violations of those work rules; and effectively enforcedthose work rules when they were violated. See, e.g., Marson Corp., 10BNA OSHC 1660, 1662, 1982 CCH OSHD ? 26,075, p. 32,804 (No. 78-3491, 1982).In the preceding section, we discussed whether Pride established thatthe conduct of its supervisory employee Cantu was unpreventable, whichis necessary to rebut the Secretary’s showing of knowledge imputed tofrom Cantu. We concluded that Pride did not prove that Cantu’s conductwas unpreventable and therefore did not rebut the Secretary’s proof ofknowledge.With regard to whether the conduct of its non-supervisory employeesReyes and Zamora was unpreventable, Pride introduced into evidence thepages that these two employees had signed acknowledging receipt of thesafety guide in August 1986, and \”agree[ing] to read all safetyinstructions pertinent to [their] jobs.\” With regard to Reyes, the workrule upon which Pride relies did not address the hazardous condition towhich he was exposed when he was working atop the tank. As the judgefound, based on the autopsy report and testimony, the multiple abrasionsand contusions on the upper front of Reyes’ head showed that he had notentered the tank voluntarily. The judge noted that under the work rule,employees \”could very well conclude\” that they did not violate the workrule by merely sticking their heads in the hole at the top of the tankto see the level of the returns inside the tank. Moreover, whenspecifically directed by a supervisor, as Reyes was by Cantu here, toperform work that could possibly cause the employee to break a safetyrule, the employee could reasonably consider the supervisor’sinstructions as overriding the safety rule. Cf. Regina Constr. Co., 15BNA OSHC 1044, 1048, 1991 CCH OSHD 29,354, p. 39,468 (No. 87-1309, 1991)(employee could not be in a hazardous location but for supervisor’s orders).With regard to Zamora, Cantu’s testimony as to what another employeetold him demonstrates that Zamora attempted to rescue Reyes andtherefore could also have entered the tank voluntarily. If this had beenthe case, Zamora also would have been in violation of the work rule.Nevertheless, the evidence also shows that Cantu, Zamora’s supervisor,was not only failing to enforce the rule, but he was breaking ithimself. Furthermore, it is arguable that the work rule does not reallyaddress the condition that Cantu and Zamora faced–the necessity for anemergency rescue. As the Secretary notes, rescue attempts are readilyforeseeable in the oil well servicing industry, yet Pride had no workrule addressing them.[[9]]Just as Pride failed to adequately train its supervisor Cantu and nowseeks to hide behind his lack of knowledge of the hazard, so does italso attempt to hide behind Reyes and Zamora’s lack of training andsupervision. As discussed above, this is not permission. See Danco, 586F.2d at 1247. Therefore, we reject Pride’s contentions that the conductof Reyes and Zamora was unpreventable.E. Summary and PenaltyBased on our findings above, we conclude that the judge did not err indetermining that Pride committed a violation of section 1910.134(a)(2).The judge found that the violation was serious under section 17(k) ofthe Act, 29 U.S.C. ? 666(k), as alleged. Pride does not challenge thatcharacterization on review. We therefore conclude that the violation wasserious.The judge assessed the proposed penalty of $560 for this violation. Inlight of the penalty factors in section 17(j) of the Act, 29 U.S.C. ?666(j), especially the gravity of the violation, and the immediate,direct relief from the hazardous atmosphere that respirators could haveprovided, we assess a penalty of $1,000.Ill. Caution SignThe judge affirmed citation no. 1, item 3, as amended, which alleges aserious violation of 29 C.F.R. ? 1910.145(c)(2)(i). [[10]] It wasundisputed that there was no caution sign warning employees against thepotential hazards involved in monitoring the returns from the opening inthe top of the tank or entering the tank for emergency rescue. Thecompliance officer testified that such signs could have caused employeesto exercise the necessary caution in light of the potential hazard.Pride’s supervisor Cantu testified that over the years he had seen \”fractanks\” with signs on them saying things like: .\”poisonous gas, do notenter.\”Pride contends that, because it did not own the tank, but rather onlyleased it, it was not responsible for providing a caution sign. As notedabove, the Fifth Circuit stated in City that an employer \”cannot shiftits statutory responsibility for the health and safety of its employeesto third parties.\” 795 F.2d at 511. Moreover, from a practicalstandpoint, there is no requirement that the sign be permanent. Nor doesthe sign need to be attached to the tank itself, but rather can be, asCantu testified he had seen, \”‘anywhere around it\” that would be visibleto employees.Pride also contends that it had taken sufficient measures to warnemployees by its safety manual. However, as discussed above, the workrule against entering confined spaces, even assuming it implements therequirements of the cited standard, was not enforced. Pride also arguesthat it did not know the contents of the atmosphere within the tank andtherefore would have had no way of knowing whether warning signs wereneeded. We reject that contention. As the discussions in the sectionsabove show, Pride did not take sufficient measures to either warn ortrain its employees, and it is now trying to hide behind the resultantlack of knowledge on its employees’ part regarding the possibility ofoxygen deficiency.Based on the considerations above, including the well-documented hazardsin the record, [[11]] and Pride’s knowledge of them, we conclude thatthe judge did not err in finding that Pride violated section1910.145(c)(2)(i). Pride does not challenge on review the seriouscharacterization of this violation. Accordingly, we affirm the violationas serious.The judge assessed the proposed penalty of $560. Based on the penaltyfactors in section 17(j) of the Act, 29 U.S.C. ? 666(j), we assess amore appropriate penalty of $200.IV. OrderFor the reasons stated above. we affirm the decision of Judge Botkin andfind no error in his conclusions that Pride committed serious violationsof sections 1910.134(a)(2) and 1910. 145(c)(2)(l). We assess respectivepenalties of $ 1,000 and $200 for these violations.Edwin G. Foulke, Jr.ChairmanDonald G. WisemanCommissionerVelma MontoyaCommissionerDated: August 17, 1992————————————————————————FOOTNOTES:[[1]] The judge characterized this testimony by Perez as \”direct andpersuasive.\” (Throughout his decision, he referred to this employee as\”Mario\” because he mistakenly stated that, instead of Perez (as theemployee spelled his own name at the hearing), his last name was Reyes,the last name of another Pride employee.) The judge specificallycredited Perez’s testimony over Cantu’s testimony that he saw Perez walkover and lean down near the opening, as if to listen. We defer to thejudge’s credibility determination. See, eg., C. Kaufman, Inc., 6 BNAOSHC 1295,1297, 1977- 78 CCH OSHD 22,481, p.27,099 (No.14249,1978).[[2]] Cantu testified that he told his crew to \”stand up\” whilemonitoring the returns. The judge specifically discredited thatstatement due to its inconsistency with Cantu’s earlier testimony thathe did not know what instructions Reyes had received,even though Cantuwas the one who had given him the order to relieve Perez. Based on ourreview of the record, we see no need to disturb the judge’s evaluationof these parts of Cantu’s testimony. Moreover, even if Cantu had giveninstructions to stand up, he was put on notice that they were not beingfollowed when, as he testified, he observed Reyes sitting near the opening.[[3]] The Secretary also alleged a serious violation of 29 C.F.R.1910.23(a)(6). which requires that a \”manhole floor opening\” shall beconstantly attended when the cover is not in place.The judge vacatedthis item. The Secretary does not challenge that ruling on review, andwe do not consider it here.[[4]] The standard Provides:? 1910-134 Respiratory protection.(a)Permissable practice.. . . .(2) Respirators shall he provided by the employer when such equipment isnecessary to protect the health of the employee. The employer shallprovide the respirators which are applicable and suitable for thepurpose intended. The employer shall be responsible for the\”establishment and maintenance of a respiratory protective program whichshall include the requirement outlined in paragraph (b) of this section.[[5]] Section1910.134(a)(1)providesIn the control of those occupational diseases caused by breathing aircontaminated with harmful dusts, fogs, fumes, mists, gases, smokes,sprays, or vapors, the primary objective shall be to prevent atmosphericcontamination. This shall be accomplished as far as feasible by acceptedengineering control measures …. When effective engineering controlsare not feasible,or while they are being instituted,appropriaterespirators shall be used pursuant to the following requirements.(Emphases added.)[[6]] This case can be appealed to the Fifth Circuit based on thelocations of the alleged violation and the principal office of theemployer. See sections 11(a) and (b) of the Act, 29 U.S.C. ? 660(a) and (b).[[7]] Pride has not acknowledged that the atmosphere in the tank wasoxygen- deficient. It suggests that the Secretary must show thepercentage oxygen in the atmosphere, which Pride notes she has failed todo. However,as the judge stated in his decision, it was not necessaryfor the Secretary to establish the percentage of oxygen in order toprove the hazard of oxygen deficiency existed. He additionally notedthat, despite Pride’s successful objection to the Secretary’sintroduction of atmospheric testing results into the record. Prideitself introduced a statement as to the results into evidence in one ofits own exhibits. We further note that the conditions at the well on theday before the accident, when nitrogen was not being inserted into thetank, are not relevant to the citation items before us.[[8]] This ANSI standard was the source of OSHA’s respiratory protectionstandard at section 1910.134. See 29 C.F.R. ? 1910.139.[[9]] Pride does not have any general safety rules on rescues from tanksor wells. Included in its work rules concerning H2S is only theadmonition: Rescuers must exercise due caution.\”[[10]] \”The standard provides:? 1910.145 Specifications for accident prevention signs and tags.(a) Scope. (1) These specifications apply to the …use ofsigns…intended to indicate…specific hazards of a nature such thatfailure to designate them may lead to accidental injury to workers….(c) Classification of signs according to use–. . . .(2) Caution signs. (i) Caution signs shall be used only to warn againstpotential hazards or to caution against unsafe practices.(Emphases added.)[[11]] In light of the oxygen-deficient atmosphere in the tank, which wefound above, a \”danger sign\” (as discussed in 29 C.F.R {sym}1910.145(c)(l)) may have been appropriate to warn of the specific dangerof asphyxiation to which employees were exposed while observing thelevel of the returns through the opening in the tank’s top.”