Full opinion text
Opinion for the Court filed PER CURIAM. PER CURIAM: These consolidated cases seek review of a rulemaking of the Mine Safety and Health Administration (“MSHA”). Representatives of both the industiy and the miners challenge the rulemaking on a number of grounds, only some of which merit discussion. We hold that the agency failed to give adequate notice of its intention to require preshift examinations at fixed-time intervals as opposed to on a shift-by-shift basis. As to all other issues we deny the petitions for review and uphold the agency’s rulemaking. I. Background This case first arose as a challenge to a set of safety rules proposed by MSHA in 1988, 53 Fed.Reg. 2382 (1988), and finalized in 1992, 57 Fed.Reg. 20,868 (1992). The rulemaking was intended to “upgrade existing provisions consistent with advances in technology, eliminate unnecessary reporting and recordkeeping requirements, minimize conflicting provisions, delete irrelevant standards, simplify and consolidate existing standards, address known hazards not now covered by standards, and clarify and reorganize standards, where necessary.” 53 Fed.Reg. 2382. Predecessor organizations of the National Mining Association (“NMA”), representing the industry, and the United Mine Workers of America, International Union (“UMWA” or the “Union”), representing the miners, challenged the 1992 rule in this Court. The Court stayed the effect of one provision, 30 C.F.R. § 75.321(a), which regulates air quality standards in bleeder entries. American Mining Congress v. Secretary of Labor, No.92-1288 (D.C.Cir. Nov. 10, 1992) (order). MSHA voluntarily stayed the effect of two additional provisions, 30 C.F.R. § 75.313, relating to fan stoppages, and 30 C.F.R. § 75.344(a)(1), regulating compressors. 57 Fed.Reg. 53,856 (1992). The remaining sections of the rule became effective on November 16, 1992. See 57 Fed.Reg. 34,683 (1992). MSHA then agreed to further review the 1992 rule and to propose revisions. With the consent of the parties the Court then stayed the petitions pending the agency’s review. American Mining Congress v. Secretary of Labor, No.92-1288 (D.C.Cir. Aug. 17, 1993) (order); American Mining Congress v. Secretary of Labor, No. 92-1288 (D.C.Cir. Oct.6, 1994) (order). In 1994, the agency published a proposed rule that adopted revisions to the 1992 version. 59 Fed.Reg. 26356. The agency published a final rule in 1996. 61 Fed. Reg. 9764. NMA and UMWA petitioned this Court for review in cases that were consolidated with the earlier challenges. The Court stayed the effect of two provisions, 30 C.F.R. §§ 75.313(d)(2) and 75.321(a)(2). National Mining Assoc. v. MSHA No. 96-1150 (D.C.Cir. June ’ 7, 1996) (orders). The remainder of the rule became effective in June, 1996. II. NMA’s Challenges A 30 C.F.R. § 75.321(a)(2) — Air Quality Standards in Bleeder Entries NMA challenges, on a number of grounds, the requirement that the oxygen level in bleeder entries remain at or above 19.5 percent. 30 C.F.R. § 75.321(a)(2). NMA asserts, first, that the requirement violates the Federal Mine Safety and Health Act (“Mine Act” or the “Act”), BO U.S.C. §§ 801-962. The Mine Act requires an oxygen level of 19.5 percent in the “active workings” of the mine. 30 U.S.C. § 863(b). An “active working! ]” is defined as “any place in a coal mine where miners are normally required to work or travel.” 30 U.S.C. § 878(g)(4). A bleeder entry, which is a ventilation device used to move methane and other gases away from areas where miners work, is entered at least once a week for inspection. See 30 C.F.R. § 75.364(a). A number of administrative law judges have held that a bleeder entry is not part of the mine’s active workings. See, e.g., Rochester & Pittsburgh Coal Company, 11 FMSHRC 1318, 1321 (1989); Rushton Mining Company, 11 FMSHRC 1506, 1507 (1989). See also 30 U.S.C. § 863(z)(2) (stating that bleeder systems should be maintained “to protect the active workings of the mine”); 30 C.F.R. § 75.334(b)(1) (describing bleeder systems as ventilation devices used to move methane and other gases “away from active workings.”). NMA asserts that Congress’s decision to provide the 19.5 percent standard only for active workings mandates a lower standard for other areas, such as the bleeder systems. The agency interprets the Act to allow for oxygen standards in any area of the mine where miners require adequate oxygen supplies. Under the familiar rules of Chevron deference, we find nothing in the Mine Act that prohibits the regulation at issue. See Chevron U.S.A., Inc. v. Natural Resources Defense Council, 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984). Under Chevron, a court first asks “whether Congress has directly spoken to the precise question at issue.” Id. at 842, 104 S.Ct. at 2781. If so, the matter is settled, “for the court, as well as the agency, must give effect to the unambiguously expressed intent of Congress.” Id. at 842-43, 104 S.Ct. at 2781-82. However, “if the statute is silent or ambiguous with respect to the specific issue, the question for the court is whether the agency’s answer is based on a permissible construction of the statute,” id. at 843, 104 S.Ct. at 2781 meaning one that is “reasonable and consistent with the statute’s purpose.” Nuclear Information Resource Service v. NRC, 969 F.2d 1169, 1173 (D.C.Cir.1992). We cannot say, under the first step of Chevron, that the Mine Act unambiguously prohibits the agency from applying the 19.5 percent oxygen requirement to bleeder entries. NMA’s interpretation of the Act employs a version of expressio unius est exclu-sio alterius; because Congress explicitly mandated safety standards in some areas of the mine, the agency is prohibited from adopting regulations not specifically provided for in the statute. We do not believe that NMA’s reading “give[s] effect to the unambiguously expressed intent of Congress.” Chevron, 467 U.S. at 843, 104 S.Ct. at 2782. Quite to the contrary, we find it to be implausible. Congress frequently adopts specific safety standards and at the same time delegates the task of supplementing the standards to agency expertise. The Mine Act specifically provides that the standards specified by Congress are not exhaustive. Section 101(a) of the Act authorizes the Secretary to “develop, promulgate, and revise as may be appropriate, improved mandatory health or safety standards for the protection of life and prevention of injuries in coal or other mines.” 30 U.S.C. § 811(a). To interpret the safety standards provided by the Act as necessarily exclusive of more extensive protections is to annul the agency’s authority under Section 101(a). Turning then to Chevron Step Two, we cannot conclude that the agency’s interpretation of the Act is unreasonable. The agency has “promulgate[d] ... improved mandatory health or safety standards for the protection of life and prevention of injuries” as authorized by Section 101(a). In doing so, the agency has borrowed a standard endorsed by Congress elsewhere in the Act. See 30 U.S.C. § 863(b). The agency’s interpretation appears eminently “reasonable and consistent with the statute’s purpose.” Nuclear Information, 969 F.2d at 1173. We therefore reject NMA’s statutory challenge. NMA also asserts that 30 C.F.R. § 75.321(a)(2) is arbitrary and capricious under the Administrative Procedure Act, 5 U.S.C. §§ 553, 706, because the agency failed to identify its reasons for requiring an oxygen level of 19.5 percent as opposed to the 18 percent oxygen standard favored by the industry. When regulating under Section 101(a) the agency is required, as always, to consider the relevant alternatives and identify the reasons for its preference. See Motor Vehicle Mfrs. Assoc, v. State Farm, 463 U.S. 29, 42-43, 103 S.Ct. 2856, 2865-66, 77 L.Ed.2d 443 (1983). As part of its explanation, the agency must “respond to specific challenges that are sufficiently central to its decision.” International Fabricare Institute v. EPA, 972 F.2d 384, 389 (D.C.Cir.1992). Several industry commenters voiced support for an 18 percent oxygen level, often citing to a recommendation by the American Conference of Governmental Industrial Hygienists (“ACGIH”). See, e.g., Comments of AMC, BCOA, and NCA; Comments of Kerr-McGee Coal Corp. The agency specifically acknowledged these comments and defended its choice by noting that bleeder entries are examined weekly by a person traveling alone who often is required to remain in the bleeder entry for an extended period. The agency cited a study by the National Institute for Occupational Safety and Health (“NIOSH”) that recommends a 19.5 percent oxygen level for most tasks. NIOSH noted that this level includes a margin of safety. The margin is vital, according to NIOSH, because “oxygen-deficient atmospheres offer little warning of the danger.” MSHA then offered two examples of mining accidents caused by inadequate oxygen supplies. The agency concluded: Because mine examiners are required to work or travel in areas where oxygen-deficient air could occur without warning, and they normally travel and work alone, there must be a requirement that provides them the protection necessary for the performance of their duties under these conditions. It is important that the level for oxygen be established above that identified as resulting in impaired judgement because it is essential that individuals traveling in these areas remain highly alert. The hazards that can exist in bleeder entries and worked-out areas include elevated methane levels, poor footing, loose and unstable roof, and water accumulations. For this reason, the final rulé adopts a minimum level of oxygen of 19.5 percent as recommended by NIOSH. 61 Fed.Reg. 9777. Given this extended discussion, we cannot say that the agency failed to respond to specific challenges or to justify the rule with sufficient clarity. At the same time we reject NMA’s contention that the agency was required to demonstrate that an oxygen standard of 18 percent would have posed a significant risk to miners. The 19.5 percent standard is permissible even without a significant risk that miners would be endangered by oxygen levels of 18 percent. In Industrial Union Department, AFL-CIO v. Amer. Petroleum Institute, 448 U.S. 607, 100 S.Ct. 2844, 65 L.Ed.2d 1010 (1980), the Supreme Court considered a provision of OSHA that authorizes the Secretary to promulgate standards that are “reasonably necessary or appropriate to provide safe or healthful employment and places of employment.” ■ 29 U.S.C. § 652(8). The Court interpreted the provision to require the agency “to make a threshold finding that ... significant risks are present and can be eliminated or lessened by a change in practices.” Industrial Union, 448 U.S. at 642, 100 S.Ct. at 2863. We note, first, that this case arises under a differently worded statute. Section 101(a) states only that the Secretary is authorized to “develop, promulgate, and revise as may be appropriate, improved mandatory health or safety standards for the protection of life and prevention of injuries in coal or other mines.” 30 U.S.C. § 811(a) (emphasis added). Arguably, this language does not mandate the same risk-finding requirement as OSHA. Even if we were to hold that MSHA was compelled by the statute to identify a significant risk posed by the existing standard, it has done so here. Contrary to the assertions of NMA’s counsel at oral argument, the regulations in effect prior to this rulemaking did not impose an 18 percent oxygen requirement; they were silent on the question of air quality in bleeder entries. At most, therefore, the agency was required to identify a significant risk associated with having no oxygen standard at all. As noted, the agency has identified a number of significant risks associated with inadequate oxygen supplies including “impairment in the ability to think and pay attention, and a reduction in coordination” as well as “adverse physiological effects.” 61 Fed.Reg. 9776. The agency pointed to an instance in which a miner was asphyxiated working in an area with inadequate oxygen supplies, and another instance in which an examiner lost consciousness. Id. The determination that 19.5 percent is appropriate, as opposed to a marginally lower standard, is a technical decision entrusted to the expertise of the agency rather than the conjecture of the Court. In any ease, as NMA conceded at oral argument, the Secretary was entitled to “‘err’ on the side of overproteetion by setting a fully adequate margin of safety.” American Petroleum Institute v. Costle, 665 F.2d 1176, 1186 (D.C.Cir.), cert. denied, 455 U.S. 1034, 102 S.Ct. 1737, 72 L.Ed.2d 152 (1982). Finally, NMA claims that the 19.5 percent standard may, in fact, increase the danger to miners by requiring hazardous changes to ventilation systems. In support, NMA relies on declarations by industry experts. We have granted the Secretary’s Motion to Strike these declarations as they are not properly part of the record. See AT&T Information Systems, Inc. v. General Services Administration, 810 F.2d 1233, 1236 (D.C.Cir.1987). Therefore, NMA’s assertions on this point are rejected as speculative. B. 30 C.F.R. § 75.323 — Allegedly conflicting requirements 30 C.F.R. § 75.323 requires a mine operator to take remedial action “at once” when methane levels in a working place or an intake air course reach 1.0 percent. NMA claims that the requirement that changes be made “at once” is irreconcilable with 30 C.F.R. § 75.370(d) which states that “[a]ny intentional change to the ventilation system ... that could materially affect the safety and health of the miners ... shall be submitted to and approved by the district manager before implementation.” NMA asserts that a change cannot be made “at once” under Section 75.323 if prior approval is necessary under Section 75.370(d). In response to comments on this point the agency stated, MSHA knows of no case where an operator has been prohibited from [making] a necessary correction for a methane problem pending a plan approval. However, in cases where intentional changes are made which could materially affect the safety and health of miners, approval is required before resumption of normal work if the changes affect the information approved in the mine ventilation plan. MSHA recognizes that some ventilation changes take time to accomplish and interprets the phrase “at once” as meaning that the work of making the necessary change to reduce methane levels begins immediately. 61 Fed.Reg. 9777 (emphasis added). The agency’s interpretation of its own regulations is entitled to deference unless it is “plainly erroneous or inconsistent with the regulation.” Jersey Shore Broadcasting Corp. v. FCC, 37 F.3d 1531, 1536 (D.C.Cir.1994). Therefore, Section 75.323 requires only that the operator immediately begin taking the necessary steps to reduce methane levels. When approval is required for a ventilation change under Section 75.370(d) the operator is required only to begin to make the necessary correction “at once” and to obtain approval before the resumption of normal work. NMA also asserts a conflict between Section 75.323 and 30 C.F.R. § 75.324 which requires that a “person designated by the operator shall supervise any intentional change in ventilation.” Section 75.324 also states that when an intentional change in the ventilation system is made “[ejleetric power shall be removed from areas affected by the ventilation change and mechanized equipment in those areas shall be shut off.” NMA does not identify what conflict it perceives in the provisions, and we are unable to identify any inconsistency. Section 75.324 could require a mine operator to depower a mine before beginning ventilation changes, however, as authoritatively interpreted, Section 75.323 requires only that the act of depower-ing begin “at once,” not that the repairs be completed immediately. 61 Fed.Reg. 9777. When Section 75.324 requires the operator to depower the plant, immediate depowering followed by the ventilation changes satisfies the requirements of Section 75.323. We therefore reject NMA’s claims of conflicting agency requirements. C. SO C.F.R. § 75.332(a)(1) — Separate Air Splits 30 C.F.R. § 75.332(a)(1) provides: Each working section and each area where mechanized mining equipment is being installed or removed, shall be ventilated by a separate split of intake air directed by overcasts, undercasts or other permanent ventilation controls. According to NMA, a separate split of intake air should be required only in each area where mechanized mining equipment is being removed. The agency considered the suggestion that it exempt the installation of longwall equipment from the requirement. The suggestion was rejected, as noted in the rule’s preamble, because installation of long-wall equipment is labor intensive and requires cutting and welding, increasing the possibility of fire or explosion. 61 Fed.Reg. 9782. This discussion indicates that the agency “examine[d] the relevant data and articulate[d] a satisfactory explanation for its action.” Motor Vehicle Mfrs., 463 U.S. at 43, 103 S.Ct. at 2866. We, therefore, reject this challenge to the rule. D. 30 C.F.R. § 75.360(a)(1) — Preshift Examinations at Fixed Intervals During preshift examinations, inspectors determine the methane and oxygen levels in a coal mine, ensure that air is flowing through the mine properly, and generally check for hazardous conditions. See 30 C.F.R. § 75.360; 30 U.S.C. § 863(d). According to MSHA, preshift examinations are “the primary means of determining the effectiveness of a mine’s ventilation system and of detecting developing hazards, such as methane accumulations, water accumulations, and bad roof.” 61 Fed.Reg. 9790. The regulation that went into effect in 1996 requires examinations within “3 hours preceding the beginning of any 8-hour interval during which any person is scheduled to work or travel underground.” 30 C.F.R. § 75.360(a)(1). This regulation reflects a break with past practice. Beginning in 1952 with the Federal Coal Mine Safety Act, ch.,877, § 209(d)(7), 66 Stat. 692, 704 (1952), Congress required pre-shift examinations in “gassy” coal mines “within four hours immediately preceding the beginning of a coal-producing shift.” The current statute, passed in 1969, requires pre-shift examinations “[wjithin three hours immediately preceding the beginning of any shift, and before any miner in such shift enters the active workings of a coal mine.” Federal Coal Mine Health and Safety Act of 1969, Pub.L. No. 91-173, § 303(d)(1), 83 Stat. 742, 768 (codified at 30 U.S.C. § 863(d)(1)). Regulations in effect between 1970 and 1992 incorporated the statutory language, requiring preshift examinations “[wjithin 3 hours immediately preceding the beginning of any shift.” See 35 Fed.Reg. 17,890,17,900 (1970) (codified at 30 C.F.R. § 75.303(a) (1991)). The 1988 proposed rule and the 1992 final rule similarly required that “[wjithin 3 hours preceding the beginning of any shift ... a certified person designated by the operator shall make a preshift examination.” See 53 Fed.Reg. 2419; 57 Fed.Reg. 20,922. The rule proposed in 1994 made only a slight grammatical change and read: “a certified person designated by the operator shall make a preshift examination within 3 hours preceding the beginning of any shift.” 59 Fed.Reg. 26,394. Comments submitted to MSHA during the rulemaking convinced the agency that the existing regulatory regime had become unworkable because some mines were no longer using standard eight hour shifts. See 61 Fed.Reg. 9791. If a mine used overlapping shifts beginning at two hour intervals, for example, one might suppose preshift examinations had to be conducted every two hours. To avoid such “controversies and misunderstandings,” id., the agency decided to establish some “reasonable period ... after which another examination is necessary,” since conditions in a mine may change rapidly, id. NMA raises both substantive and procedural objections to the new rule. 1. Substantive Objections NMA’s main substantive objection is that the regulation misreads “shift” in 30 U.S.C. § 863(d)(1) to mean an eight hour period. We do not see why the agency’s interpretation of “shift” is impermissible. The word certainly can bear this meaning. In many instances and in varied contexts, Congress has treated eight hours as the standard work day. See, e.g., 5 U.S.C. § 6101(a)(3)(D) (heads of federal agencies to provide that “the basic nonovertime workday may not exceed 8 hours”); 10 U.S.C. § 2431(b)(4)(B)® (for defense acquisition purposes, “most efficient production rate” defined with reference to eight hour shifts); 29 U.S.C. § 207(e)(7) (under Fair Labor Standards Act, “regular rate” of pay does not include premium pay for work outside “the basic, normal, or regular workday (not exceeding eight hours)”); 42 U.S.C. § 5196(j)(8) (when construction work is financed with federal funds made available to states for emergency preparedness purposes, construction workers must receive overtime for hours worked “in excess of eight hours in any workday”); 49 U.S.C. § 28301(a) (for certain railroad employees, “8 hours shall be a day’s work and the standard day’s work for determining [ ] compensation”). At the least, 30 C.F.R. § 75.360(a)(1) is a reasonable interpretation of open-ended statutory language. That is enough for us to defer to the agency under the familiar principles of Chevron, 467 U.S. at 842-45, 104 S.Ct. at 2781-82. Even if the regulation departed from the literal terms of 30 U.S.C. § 863(d)(1), that would not make it invalid. Section 863 contains “interim mandatory safety standards applicable ... until superseded in whole or in part by improved mandatory safety standards promulgated by the Secretary under the provisions of section 811 of this title.” 30 U.S.C. § 861(a). Section 811 authorizes the Secretary of Labor to “develop, promulgate, and revise as may be appropriate, improved mandatory health or safety standards for the protection of life and prevention of injuries in coal or other mines.” 30 U.S.C. § 811(a). We see no reason why we should not think of 30 C.F.R. § 75.360(a)(1) as just such an “improved mandatory safety standard[ ]” issued in light of changed circumstances in the mining industry. NMA also claims that 30 C.F.R. § 75.360(a)(1) is infirm because evidence in the record did not support a finding that safety considerations require conducting pre-shift examinations at eight hour intervals (rather than, say, nine or ten hour intervals). But NMA does not contest the agency’s finding that the mining industry’s use of overlapping shifts and other unconventional work schedules made it desirable to clarify when preshift examinations are required. What matters is whether the agency’s choice of fixed eight hour intervals was a reasonable approach to the problem, not whether it was the only approach that would ensure miner safety. NMA has not shown that using fixed time intervals is unreasonable, or that eight hours is an unreasonable choice of interval. 2. Notice NMA’s procedural objection is that MSHA failed to comply with the notice and comment provisions of the Administrative Procedure Act, 5 U.S.C. § 553, as 30 U.S.C. § 811(a) required it to do. NMA argues that the 1994 proposed rule, which followed the longstanding practice of requiring preshift examinations three hours before shifts begin, provided no notice that the agency would consider abandoning that approach in favor of preshift examinations at fixed intervals. Had it received proper notice, NMA says, it would have submitted comments to the agency showing that the new regulation, in conjunction with local law in some states, demands an excessive number of preshift examinations serving no safety purpose. It is conceivable that if the agency had received such comments, it would have adjusted the final rule to take into account overlapping state law requirements. Agencies are not limited to adopting final rules identical to proposed rules. No further notice and comment is required if a regulation is a “logical outgrowth” of the proposed rule. See, e.g., Kooritzky v. Reich, 17 F.3d 1509,1513 (D.C.Cir.1994). Our eases offer no precise definition of what counts as a “logical outgrowth.” We ask “whether ‘the purposes of notice and comment have been adequately served.’ ” American Water Works Ass’n v. EPA, 40 F.3d 1266, 1274 (D.C.Cir.1994) (quoting Fertilizer Inst. v. EPA, 935 F.2d 1303, 1311 (D.C.Cir.1991)). Notice was inadequate when “the interested parties could not reasonably have ‘anticipated the final rulemaking from the draft [rule].’ ” Id. at 1275 (quoting Anne Arundel County v. EPA, 963 F.2d 412, 418 (D.C.Cir.1992)). “[W]e inquire whether the notice given affords ‘exposure to diverse public comment,’ ‘fairness to affected parties,’ and ‘an opportunity to develop evidence in the record.’” Association of Am. Railroads v. Dep’t of Transp., 38 F.3d 582, 589 (D.C.Cir.1994) (quoting Small Refiner Lead Phase-Down Task Force v. EPA, 705 F.2d 506, 547 (D.C.Cir.1983)). It is clear to us that 30 C.F.R. § 75.360(a)(1) is not a “logical outgrowth” of the 1994 proposed rule. The regulation that went into effect in 1992, like the prior regulation, treated the timing of preshift examinations in the same way as the statute. In the discussion accompanying the 1992 final rule, the agency explained how it expected mine operators using overlapping shifts to comply. See 57 Fed.Reg. 20,893. The 1994 proposed rule made no substantive changes regarding when preshift examinations should occur. See 59 Fed.Reg. 26,394 — 95. The discussion accompanying the proposed rule dealt with preshift examinations in some detail, but the agency did not mention any problems with the timing of the examinations, and it did not express any interest in changing that aspect of the rule. See 59 Fed.Reg. 26,373-75. None of this would, have alerted a reasonable interested party that the final rule might alter the provisions about when preshift examinations must be conducted. MSHA tells us that because the proposed rule addressed how preshift examinations would be conducted, it “raised the basic question of when such examinations should be conducted.” If the 1994 proposed rule had been the agency’s first attempt to regulate preshift examinations, it might well have been reasonable to think that all aspects of the rule were on the table- and subject to revision. But the agency could not have expected parties to realize that it would consider abandoning a regulatory approach that dates to 1952 and a specific requirement that had been unchanged for twenty-five years simply because it was revising related regulations. MSHA also argues that whatever the defects of the notice provided by the agency itself, NMA had actual notice that the agency was considering a regulation requiring pre-shift examinations at fixed intervals. We have said that “even if [an] agency has not given notice in the statutorily prescribed fashion, actual notice will render the error harmless.” Small Refiner Lead Phase-Down Task Force, 705 F.2d at 549. MSHA points out that an NMA member, Energy West Mining Co., proposed requiring preshift examinations at standard eight hour intervals both in written comments to the agency and at a public hearing attended by representatives of numerous members of NMA’s predecessors. NMA admits that it had a transcript of that hearing. And a local trade group, the Utah Mining Association, made the same recommendations as Energy West in its written comments, suggesting that this was a topic of interest and discussion in the industry. We are willing to assume that NMA knew of the comments suggesting preshift examinations at fixed intervals. But such knowledge alone cannot substitute for notice from the agency. Even if a party knows that a commenter has made some novel proposal to an agency during a rulemaking, the party cannot be expected to respond unless it has some reason to believe the agency will take the proposal seriously. Actual notice, then, depends on awareness that the agency, despite its failure to alert the public, is considering adopting what the commenter has suggested. Cf. Mid-Tex Elec. Coop., Inc. v. FERC, 773 F.2d 327, 339 (D.C.Cir.1985) (“Petitioners had actual notice that FERC might adopt the alternative it ultimately chose.”); Sierra Club v. Costle, 657 F.2d 298, 355 (D.C.Cir.1981) (parties had actual notice of “EPA’s focus” on standard). Here, MSHA has given us no reason to suppose that NMA suspected a change in the forty year old practice of requiring preshift examinations a fixed number of hours before shifts begin. The petition for review is, therefore, granted with respect to 30 C.F.R. § 75.360(a)(1). E. SO C.F.R. § 75.360(b)(9) — Preshift Examinations of Electrical Installations and Compressors The regulations include a list of locations subject to preshift examinations. The new rule adds to the list certain “[underground electrical installations ... and areas where [certain] compressors ... are installed if the electrical installation or compressor is or will be energized during the shift.” 30 C.F.R. § 75.360(b)(9). NMA raises two objections to this regulation. 1. Other Regulations NMA’s first objection is that two other new regulations, 30 C.F.R. §§ 75.340 and 75.344, adequately address the hazards associated with electrical installations and compressors. Those regulations are aimed at containing fires, primarily through fire suppression systems and by housing electrical installations and compressors “in noncombustible structures or areas.” NMA’s contention is not, however, properly before us. No party raised it during the ralemaking. When a court reviews mine safety and health standards, “[n]o objection that has not been urged before the Secretary shall be considered by the court, unless the failure or neglect to urge such objection shall be excused for good cause shown.” 30 U.S.C. § 811(d). NMA points out that two industry com-menters told the agency that they thought proposed § 75.360(b)(9) was unnecessary and wasteful. One commenter asserted that electrical installations are safely designed and have a safe operating history. The other told the agency that the type of equipment covered by § 75.360(b)(9) is already “protected by mandated electrical requirements, and, in many cases, continuous monitoring systems.” But NMA’s objection is not, as the commenters had argued, that § 75.360(b)(9) is unjustified against the backdrop of prior regulations regarding electrical requirements and monitoring. Rather, NMA argues that § 75.360(b)(9) is unnecessary in light of the additional safety now provided by the new steps mine operators must take under §§ 75.340 and 75.344 to contain fires. No party made that claim during the rulemak-ing. NMA suggests that this failure should be excused because §§ 75.340 and 75.344 were, in its words, “in flux” at the time of the rulemaking. Although the agency partially stayed an earlier version of § 75.344 in 1992, both §§ 75.340 and 75.344 were in the 1994 proposed rule that included proposed § 75.360. See 59 Fed.Reg. 26,394. We see no reason why §§ 75.340 and 75.344 were any more in flux and unworthy of attention than § 75.360. NMA also argues that since the commenters told MSHA that they believed earlier regulations made § 75.360(b)(9) unnecessary, the agency must have known that the commenters would also consider § 75.360(b)(9) unnecessary after the adoption of further safety standards. Be that as it may, 30 U.S.C. § 811(d) does not provide for constructive notice to the agency. Objections must actually have been made. 2. Consistency with 30 U.S.C. § 863(d)(1) NMA’s second objection to 30 C.F.R. § 75.360(b)(9) is that the regulation somehow contradicts 30 U.S.C. § 863(d)(1). Section 863(d)(1) is the statutory provision regarding preshift examinations. The alleged contradiction is that while the statute distinguishes the “active workings” of a coal mine from other areas, the regulation requires examination of electrical installations and compressors wherever they may be. But the statute says that “before any miner ... enters the active workings of a coal mine, certified persons designated by the operator of the mine shall examine such workings and any other underground area of the mine designated by the Secretary or his authorized representar, tive.” 30 U.S.C. § 863(d)(1) (emphasis added). The italicized language contemplates regulations like § 75.360(b)(9) requiring pre-shift examinations of mine areas other than the active workings. In any event, tension between 30 U.S.C. § 863(d)(1) and 30 C.F.R. § 75.360(b)(9), is no basis for striking down the regulation. As noted above, the provisions of 30 U.S.C. § 863 are “interim mandatory safety standards applicable ... until superseded in whole or in part by improved mandatory safety standards promulgated by the Secretary under the provisions of section 811....” 30 U.S.C. § 861(a). Section 75.360(b)(9) is plainly authorized by the Secretary’s general power to promulgate “mandatory health or safety standards for the protection of life and prevention of injuries in coal or other mines,” 30 U.S.C. § 811(a). F. SO C.F.R. § 75.362(d)(2) — Methane Testing with Long Probes The regulations require on-shift methane testing “[a]t the start of each shift at each working place before electrically operated equipment is energized,” “[immediately before equipment is energized, taken into, or operated in a working place,” and “[a]t 20-minute intervals ... during the operation of equipment in the working place.” 30 C.F.R. § 75.362(d)(1); see also 30 U.S.C. § 863(h). It is important that methane testing be done at the “face” — where coal is being mined. This is where methane is most likely to build up to the levels at which an explosion is possible. It is also important that miners not venture forward of areas in which the mine roof is supported. For these reasons, 30 C.F.R. § 75.362(d)(2) requires that on-shift methane tests be done “at the face from under permanent roof support, using extendable probes or other acceptable means.” Because some mines have equipment that allows mining at a face up to forty feet forward of the permanently supported roof, this regulation may require using methane detectors mounted on probes that extend to lengths more than forty feet. NMA raises four objections. 1. Back Injuries NMA claims that using probes more than twenty feet long will lead to back injuries. As evidence, it cites the comments of a mining engineer at a public hearing. He estimated the weight a miner using a thirty foot probe would have to bear and concluded: “You got muscles acting in opposite directions - I’m firmly convinced you’re going to have back injuries as a result of this requirement.” (The miners’ union did not express any concern about back injuries among its members.) The agency considered the possibility of back injuries. Noting that probes up to forty feet long have been used successfully, it concluded that the regulation does not'present an “undue risk of back injuries.” 61 Fed. Reg. 9801. No party presented the agency with any medical evidence on this subject. NMA relies on a mining engineer, not a medical professional, who had not participate ed in his company’s study of back injuries. Miners who spoke at public hearings said that forty foot probes could be heavy and difficult to use, but they did not describe back injuries, and they said that forty foot probes do work. The record also shows that at least under some circumstances probes may be mounted with feet (called “salamanders”) or other devices to reduce the strain on miners’ backs. And it appears that miners in Pennsylvania have been using such lengthy probes without a significant rise in back problems. The agency’s determination that the risk of back injuries did not outweigh the safety benefits of using long probes is not arbitrary or capricious. 2. Consistency with 30 C.F.R. § 75.323(a) Under 30 C.F.R. § 75.323(a), methane testing must be done “at least 12 inches from the roof, face, ribs, and floor.” NMA claims that 30 C.F.R. § 75.362(d)(2) is inconsistent with § 75.323(a) because it is too difficult to maneuver a methane monitor at the end of a forty foot probe well enough to comply with § 75.323(a). NMA points to the comments of one miner who said that he could not keep a twenty-five foot probe off the ground and the statement of a mining union representative that probes with salamanders are “somewhat difficult to use sometimes, especially if' you got a lot of spillage on the bottom.” Our initial problem with NMA’s argument is its premise. It is hardly clear that § 75.323(a) covers tests conducted pursuant to § 75.362(d)(2). Section 75.323(a) says that it applies to “[t]ests for methane concentrations under this section.” So it appears that methane tests conducted under another section need not comply with § 75.323(a). Our only hesitation about treating this point as dispositive is that by its own terms § 75.323 does not require any tests at all; the section is devoted to explaining what steps must be taken when various concentrations of methane are detected. It is thus hard to see what purpose § 75.323(a) might serve if its requirements do not apply to tests conducted under other sections. Putting that aside, we still sustain the regulation. Apart from the miner who could not keep a twenty-five foot probe off the ground, the evidence before the agency showed that while long probes might be difficult to use, they do work. At public hearings, at least two miners reported successfully using forty foot probes, one of whom said that such probes “were a little hard to handle but still they performed their job.” And the union official who discussed difficulties maneuvering salamander-equipped probes “if you got a lot of spillage on the bottom” went on the say: “[Ujltimately they work. They ... can and will work.” 3. Machine-Mounted Monitors NMA also objects to the agency’s rejection of the suggestion that on-shift methane testing be done using methane monitors mounted on the mining equipment working at the face. The agency points out that mining machinery is not constantly operating at the face. As NMA agreed at oral argument, the machinery is periodically withdrawn from the face, and methane may accumulate in the face area while the equipment is absent. So testing with a monitor mounted on a probe (or through some other means) is necessary to measure methane levels at the face before the mining machinery — which is a potential source of ignition — returns to the face area or enters the face area for the first time. The same is true if equipment in the face area is shut down; methane testing is necessary before the equipment is reenergized and becomes a possible ignition source. Beyond insisting at oral argument that it “makes no sense whatsoever,” NMA has not given us any reason to doubt this justification of the regulation. Still, the agency could have been clearer about all this during the rulemaking. In adopting the final rule, MSHA said that machine-mounted monitors are unacceptable because they allow testing only from fixed locations and not at “various locations in the face area.” 61 Fed.Reg. 9801. It is not obvious that this is the same rationale presented to the court. Perhaps when the agency said that the problem with machine-mounted monitors is that they can only be used from fixed locations, it meant that such a monitor can only measure methane wherever the machine happens to be located, which is not always at the face. In evaluating agency action, we look at the reasons given by the agency, not “counsel’s post hoc rationalizations.” Motor Vehicle Mfrs., 463 U.S. at 50, 103 S.Ct. at 2870. “[W]e will, however, ‘uphold a decision of less than ideal clarity if the agency’s path may reasonably be discerned.’ ” Id. at 43, 103 S.Ct. at 2866 (quoting Bowman Transp., Inc. v. Arkansas-Best Freight Sys., Inc., 419 U.S. 281, 286, 95 S.Ct. 438, 442, 42 L.Ed.2d 447 (1974)). NMA has not claimed ignorance of the actual reasons behind the agency’s rejection of machine-mounted monitors; and it has offered no response to the regulation’s justification as articulated before the court. We therefore will not invalidate the regulation on the ground of inadequate agency explanation. 4. Technology Forcing and Enforcement Issues NMA’s fourth objection is that 30 C.F.K. § 75.362(d)(2) violates the standards for acceptable “technology forcing.” According to NMA, Congress intended MSHA to defer the effective date of regulations that require currently unavailable equipment. NMA also faults the agency for not following up on comments by the Bureau of Mines that it was developing an “optical methanometer” to allow methane testing from a distance. Section 75.362(d)(2) is not, as we see it, a technology-forcing standard. Forty foot extendable probes were available at the time this regulation was adopted. Miners described successfully using forty foot probes. And at a public hearing, a union official provided the name, address, and telephone number of one manufacturer of such devices. It may be that forty foot extendable probes were not immediately available in sufficient quantities, but NMA acknowledges that the agency initially allowed mine operators to demonstrate compliance with the regulation by producing purchase orders for the probes they would need. NMA does not explain why this did not sufficiently accommodate the industry’s needs. Nothing about the agency’s enforcement position is arbitrary or capricious or inconsistent with any purported congressional intent that mine operators not be forced to comply with regulations before the required technology exists. As to the Bureau of Mines’s comment about an “optical methanometer,” it is unclear what more NMA thinks MSHA should have done. The regulation requires methane tests “using extendable probes or other acceptable means.” There is nothing to indicate that such a device would not fall into the category of “other acceptable means.” That technology superior to extendable probes may eventually become available is no reason for not requiring probes in the meantime. III. UMWA’s Challenges We turn now to the challenges brought by the Union, the first of which are premised on the Union’s contention that the rules violate the “no-less protection” rule of Section 101(a)(9) of the Act. 30 U.S.C. § 811(a)(9). Under the no-less protection rule, the Secretary’s authority to replace existing mandatory health and safety standards is subject to the limitation that “[n]o mandatory health or safety standard ... shall reduce the protection afforded miners by an existing mandatory health or safety standard.” 30 U.S.C. § 811(a)(9). This Court has interpreted the rule to require that when new standards replace existing mandatory health or safety standards it is not sufficient that the new standards demonstrate a reasonable accommodation of the competing goals of safety and efficient coal mine operation. The statute expressly mandates that no reductions in the level of safety below existing levels be permitted, regardless of the benefits accruing to improved efficiency. United Mine Workers v. Dole, 870 F.2d 662, 666 (D.C.Cir.1989). The rule of no-less protection is a “strict one” that imposes “an explicit constraint on the Secretary’s authority.” Id. at 673 n. 19, 666. However, while the Act imposes unusual limitations on the Secretary’s authority, it does not require that this Court disregard well-established principles of deference to agency action. Section 101(a)(9) requires the agency to state the basis for its conclusion that the rule has been satisfied, but this Court’s review of that substantive determination is, as always, “highly deferential and presumes the validity of agency action.” Id. at 666 (quoting Motor Vehicle Mfrs., 719 F.2d at 1164). With these principles in mind, we turn to the Union’s no-less protection challenges. In each case we find no grounds to conclude that the Secretary failed to engage in reasoned decisionmaking. A. SO C.F.R. § 75.313(d)(2) — Miners May Stop Evacuation Upon Fan Restart Underground coal mines must be “ventilated by one or more main mine fans.” 30 C.F.R. § 75.302. “The main mine fan provides the pressure that causes air to move through the mine to dilute and carry away explosive and toxic gases, dusts and fumes.” 61 Fed.Reg. 9769. A mine must be evacuated if the main mine fan stops. The old regulation required mine operators to develop a plan providing “that when any mine fan stops, immediate action shall be taken ... to withdraw all persons from the working sections, ... [and] to provide for withdrawal of all persons from the mine if ventilation cannot be restored within [a] reasonable time.” 30 C.F.R. § 75.321 (1991). Unless the agency approved a different time period, “reasonable time” meant fifteen minutes. 30 C.F.R. § 75.321-1 (1991). The new rule does not rely on plans for individual mines. Instead, it imposes blanket requirements on all mines that if the main mine fan stops “[e]veryone shall be withdrawn from the working sections and areas where mechanized mining equipment is being installed or removed,” 30 C.F.R. § 75.313(a)(3), and that “[i]f ventilation is not restored within 15 minutes ... [e]veryone shall be withdrawn from the mine,” 30 C.F.R. § 75.313(c)(1). The new rule also addresses the situation in which the fan restarts before miners have finished evacuating the mine: “If ventilation is restored to the mine before miners reach the surface, the miners may return to underground working areas only after an examination of the areas is made ... and the areas are determined to be safe.” 30 C.F.R. § 75.313(d)(2). The Union claims that § 75.313(d)(2) violates the no-less protection rule because it allows miners to remain underground after the fan restarts, whereas the old standard contained no such provision. The problem with this claim is that while the old standard did not expressly permit the practice, it also did not prohibit miners from remaining underground after ventilation was restored while they waited for their working areas to be examined before returning to work. The old regulation said nothing at all about what happens when the fan restarts before miners have left the mine, and it certainly did not require that evacuation continue. So the new rule does not appear to be any less protective than the old one. The Union suggests that the new rule reduces safety because it permits miners in all mines to remain underground after the fan restarts, while the old rule left this matter to the plans the agency approved for individual mines. The Union reasons that while some plans may have allowed miners to remain underground, others may have required evacuation to continue even after the fan restarted, and in all cases the agency had the power to require that a mine’s plan provide for such continuing evacuation. But the agency found that § 75.313(d)(2) reflects what was already the mining industry’s “general practice.” 61 Fed.Reg. 9775; see also 57 Fed.Reg. 20,875. Of plans developed under the old regulation, slightly more than 25% explicitly provided that miners would remain underground if they had not yet left the mine when the fan restarted. More importantly, no plan prevented a mine operator from following industry practice and keeping miners underground after the fan restarted. So nothing has changed under the new rule. Under both the old and the new rules, all mine operators have the option of keeping miners underground if they have not yet left the mine when the main mine fan restarts. Nothing about the new rule should make them any more or less likely to do so. B. 30 C.F.R. § 75.313(c)(2) — Deenergization of Electric Power Circuits When the Fan is Stopped 30 C.F.R. § 75.313(e)(2) requires that unless ventilation is restored within 15 minutes after a main mine fan stops electric power circuits shall be deenergized. The section creates an exception for power circuits that operate transportation equipment used to evacuate miners. In such cases, the circuits “need not be deenergized if located in areas or haulageways where methane is not likely to migrate to or accumulate.” The Union argues that the new standard provides less protection to miners than the previous standard, 30 C.F.R. § 75.321, which required “immediate action ... to cut off the power in the mine” without an exception for transportation equipment. The Union argues that the safer course is to deenergize and evacuate miners by foot. We reject the Union’s challenge because we are required to defer to the agency on factual determinations underlying its decision. In this case, the agency has determined that the safety benefit gained by rapid evacuation of miners outweighs the risk of ignition. We are poorly positioned to second-guess the agency on the balancing of these two concerns. C. 30 C.F.R. § 75.311(c) — Mine Operators Can Order Miners Underground with Only “Back-Up” Fans for Ventilation Section 75.311(c) provides that “[w]hen a back-up fan is used that does not provide the ventilating quantity provided by the main mine fan, persons may be permitted in the mine and electric power circuits may be energized as specified in the approved ventilation plan.” The pre-1992 standard did not mention “back up” fans, although it did contemplate the use of multiple fans. 30 C.F.R. § 75.300-3(c) (1991). The Union contends that § 75.311(c) violates the no-less protection rule because “[a]llowing the use of back-up fans can potentially endanger miners,” as their use could disturb precise ventilation systems which “produce a delicate balance of air velocities, quantities, and pressures.” The Union relies on a report of an investigation at a mine that concluded, in part, that upon the failure of the mine fan, “disruption in ventilation virtually stopped the flow of air” in the mine, thereby allowing methane to accumulate. The Union also contends that § 75.311(c) is too vague, in that “the Secretary has failed to adequately set forth any criteria for what specific activities will be allowed and under what specific ventilating conditions.” The Secretary points out, however, that “since [s]eetion 75.311(e) strictly regulates a practice which was unregulated in the past, it is clear that ... protection by definition is increased under the new standard.” Under the new standard, when the main mine fan is not in operation, the mine operator may only permit persons to enter the mine if a backup fan is used, and if the tasks they are to perform are those specified in an approved ventilation plan. See 57 Fed.Reg. 20,868, 20,873 (1992). The Secretary further points out that the new standard responds to the current practice of using back-up fans. Further, he maintains persuasively that § 75.311(c) is not vague because the regulation makes clear that an approved ventilation plan must assure that when back-up fans are relied upon, persons may enter the mine only for “activity which is related to maintaining the mine in a safe condition,” such as “pumping, urgent roof support installation, or other safety-related work.” 59 Fed.Reg. 26,356, 26,361 (1994). In addition, the production of coal when a back-up fan is in use still requires approval by the Secretary, as it “would not be permitted unless the mine were adequately ventilated and a new ventilation plan has been approved.” Id. Put otherwise, the new regulations ensure that when backup fans are in use that provide less than full ventilation, the range of permissible activities will be limited to those that are emergency in nature, and that can safely be performed with less ventilation than usual. Hence, we conclude that the Secretary has met his no-less protection burden. D. SO C.F.R. § 75.311(b)(1) — Intentional Fan Stoppage Section 75.311(b) must be read in conjunction with § 75.311(a), which specifies the circumstances in which an operator may intentionally stop the main mine fan. Under the prior standard, a mine operator could stop the mine fan unilaterally only for “[scheduled maintenance or adjustments on idle days when all men other than those performing evaluation or adjustments are withdrawn from the mine and the mine power is cut off.” 30 C.F.R. § 75.300-3(a)(l) (1991). For all other stoppages, the mine operator was required to obtain written permission “from an authorized representative of the Secretary.” Id. § 75.300-3(a)(3) (1991). The Union contends that § 75.311(b)(1) violates the no-less protection rule because the standard “would allow the [mine] operator, without permission, to allow a greater number of miners into the mine, while the fan is stopped, to engage in more activities than previously allowed,” and because “the standard is vague and does not adequately limit the number of miners and scope of work allowed.... ” The Secretary notes that the new standard does not create any additional grounds for stopping a fan intentionally that were not permissible under the prior standard. Rather, § 75.311(a) and § 75.311(b)(1) simply “clarif[y] what type of work may be conducted underground during an intentional fan stoppage, and by whom.” Further, the standard is not impermissibly vague because it allows “[o]nly persons necessary” to accomplish the tasks described in § 75.311(a) and § 75.311(b)(1) to enter the mine when the fan is stopped. In further defining who will be permitted to enter a mine during a stoppage, the Secretary relies on the preamble to the 1994 proposed rule that states: “[t]he maintenance or repair work which could not be made while the fan is operating is limited to work or repair which would endanger the safety of the worker if the fan were operating.” 59 Fed.Reg. 26,361-62. Thus, the new rule is different only in that while the mine operator was previously required to obtain the Secretary’s prior approval for stoppages that did not take place on idle days, the regulation now specifies when such stoppages are permissible, and what work may be performed during the stoppage. The Union offers nothing to counter the Secretary’s contention that substituting a requirement for prior approval with a detailed set of compulsory regulations will not lessen safety. Moreover, the Secretary’s response demonstrates that the Union’s vagueness challenge is meritless. While the previous standard permitted intentional fan stoppage for “[scheduled maintenance or adjustments,” 30 C.F.R. § 75.300-3(a)(l) (1991), and permitted persons performing such maintenance or adjustments to enter the mine at such times, the new regulations limit access to persons evaluating the effects of the fan stoppage or restart, or performing maintenance or repair work that “cannot otherwise be made while the fan is operating.” § 75.211(b)(1). The category of circumstances and persons who may enter the mine during a stoppage is thus more specifically defined under the new rule than it was previously. E. SO C.F.R. § 75.360(b) — Preshift Examinations Both the prior and new standards require a certified examiner to conduct an examination of any working area of the mine that miners will enter during the subsequent work shift. The preshift examination must be made at fixed intervals, “within three hours preceding the beginning of an 8-hour interval during which any person is ... to work or travel underground.” 30 C.F.R. § 75.360(a)(1) (1996). The prior standard, 30 C.F.R. § 75.303(a) (1991), required the examiner to investigate several specified areas of the mine for specific hazards, as well as for violations of mandatory health and safety standards. The Union contends that § 75.360(b) decreases the level of protection afforded miners by the preshift examination by deleting the requirement that the examiner search for “violations of mandatory health or safety standards,” and requiring instead that “[t]he person conducting the preshift examination shall examine for hazardous conditions, test for methane and oxygen deficiency, and determine if the air is moving in its proper direction” in several delineated locations within the mine. 30 C.F.R. § 75.360(b). Specifically, the Union maintains that the eliminated requirements as to safety and health standards “encouraged mine operators to take steps to remove the unsafe conditions.” [The] examiner shall ... examine for such other hazards and violations of the mandatory health or safety standards, as an authorized representative of the Secretary may from time to time require ... If such mine examiner finds a condition which constitutes a violation of a mandatory health or safety standard or any condition which is hazardous to persons who may enter or be in such area, he shall indicate such hazardous place by posting a “danger” sign conspicuously at all points which persons entering such hazardous place would be required to pass, and shall notify the operator of the mine. The Secretary emphasizes, however, that the focus of the prior standard was on identifying and correcting developing hazards. Relying on the statement made in promulgating § 75.360(b) in 1992, that “the final rule does not include a provision authorizing expansion of the preshift examination to include examination for violations of mandatory standards,” .57 -Fed.Reg. 20,894, the Secretary contends that he “never construed the previous standard to require identification of every violation of a mandatory standard, regardless of whether it involved a currently hazardous condition or not.” The Secretary relies on two phrases in the prior standard to support his position. First, under § 75.303(a) (1991), the Secretary was to determine “from time to time” to what extent preshift examinations would involve examination for violations of mandatory health and safety standards. Second, the prior standard should be interpreted, in the Secretary’s view, as requiring examinations only of health and safety violations that would be characterized as “hazardous” under § 75.360(b). The Secretary contends that because the previous rule only required examination of standard violations that were hazardous or that had been specially designated by the Secretary, § 75.360(b), which requires examination of all hazardous conditions, is consistent with the no-less protection rule. The Union does not offer any evidence to dispute the Secretary’s position. The Secretary properly emphasizes that because the purpose of the examination is to identify current hazardous conditions, requiring reporting of all instances of noncompliance with safety and health standards could distract examiners from the primary focus of their task, and lessen the efficiency of examinations. In repromulgating § 75.360(b) in 1996, the Secretary stated: Preshift examinations assess the overall safety conditions in the mine; assure that critical areas are properly ventilated; assure that the mine is safe to be entered by miners on the oncoming shift; identify hazards, whether violations or not, for the protection of miners; and through this identification facilitate correction of hazardous conditions. The preshift examination requirements in the final rule are intended to focus the attention of the examiner in critical areas. This approach is consistent with the fundamental purpose of preshift examinations which is to discover conditions that pose a hazard to miners. MSHA is persuaded that to require examiners to look for violations that might become a hazard could distract examiners from their primary duties. 61 Fed.Reg. 9,764, 9,793 (1996). The comments submitted by mine operators further emphasize the need to permit examiners to perform their task efficiently by focusing on identifying hazards without also being required to investigate all violations of health and safety standards. As the Secretary observes, the comments “support the conclusion that requiring