North America's Building Trade v. OSHA , 878 F.3d 271 ( 2017 )


Menu:
  •  United States Court of Appeals
    FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued September 26, 2017        Decided December 22, 2017
    No. 16-1105
    NORTH AMERICA’S BUILDING TRADES UNIONS,
    PETITIONER
    v.
    OCCUPATIONAL SAFETY & HEALTH ADMINISTRATION
    AND UNITED STATES DEPARTMENT OF LABOR,
    RESPONDENTS
    CHAMBER OF COMMERCE OF THE UNITED STATES OF
    AMERICA, ET AL.,
    INTERVENORS
    Consolidated with 16-1113, 16-1125, 16-1126,
    16-1131, 16-1137, 16-1138, 16-1146
    On Petitions for Review of a Final Rule of the Occupational
    Safety & Health Administration
    William L. Wehrum and Bradford T. Hammock argued the
    cause for the Industry Petitioners. Susan F. Wiltsie, David
    Craig Landin, Tressi L. Cordaro, Michael B. Schon and Linda
    E. Kelly were with them on brief. Elizabeth C. Chandler
    Clements entered an appearance.
    2
    J. Michael Connolly argued the cause for the Petitioners-
    Intervenors Chamber of Commerce of the United States, et al.
    William S. Consovoy, Steven P. Lehotsky and Sheldon B.
    Gilbert were with him on brief.
    Jeremiah A. Collins and Victoria L. Bor argued the cause
    for the Union Petitioners. Randy S. Rabinowitz, Lynn K.
    Rhinehart, Richard J. Brean and Ava Barbour were with them
    on brief. Stephen A. Yokich entered an appearance.
    Kristen M. Lindberg and Lauren S. Goodman, Senior
    Attorneys, and Louise McGauley Betts, Attorney, United States
    Department of Labor, argued the cause for the Respondents.
    On brief were Nicholas C. Geale, Acting Solicitor of Labor,
    Heather R. Phillips, Counsel for Appellate Litigation,
    Nathaniel I. Spiller, Counsel for Health Standards, and Anne R.
    Godoy and Allison G. Kramer, Senior Attorneys.
    Victoria L. Bor argued the cause for the Respondents-
    Intervenors. Jeremiah A. Collins, Randy S. Rabinowitz, Lynn
    K. Rhinehart, Richard J. Brean and Ava Barbour were with her
    on brief.
    William L. Wehrum, Susan F. Wiltsie, David Craig
    Landin, Bradford T. Hammock, Tressi L. Cordaro and Linda
    E. Kelly were on brief for the Industry Respondent-Intervenors.
    Lisa W. Jordan was on brief for the amici curiae The
    American Thoracic Society, et al. in support of the respondent.
    Adam Babich entered an appearance.
    Before: GARLAND, Chief Judge, and HENDERSON and
    TATEL, Circuit Judges.
    3
    PER CURIAM: Respirable crystalline forms of silica, 1 a
    compound made of silicon and oxygen, are commonly found
    in workplaces with rock, sand, gravel, concrete, and brick.
    Exposure to silica is one of the oldest known occupational
    hazards. And the health effects of exposure to silica—most
    commonly silicosis, a progressive and irreversible lung disease
    caused by the inflammatory effects of silica—are not a thing of
    the past. “Currently, silicosis is the most prevalent chronic
    occupational disease in the world.” ROBBINS & COTRAN,
    PATHOLOGIC BASIS OF DISEASE 690 (9th ed. 2015).
    In the United States, more than two million workers are
    currently exposed to some level of silica. In 2016, the
    Occupational Safety and Health Administration (OSHA), an
    agency within the United States Department of Labor,
    published a final rule regulating workplace exposure to silica.
    Occupational Exposure to Respirable Crystalline Silica, 
    81 Fed. Reg. 16,285
     (Mar. 25, 2016) (codified at 29 C.F.R. Pts.
    1910, 1915, and 1926) (Silica Rule or Rule). Petitions to
    review the Rule came from both sides; a collection of industry
    petitioners (Industry) believes OSHA impermissibly made the
    Rule too stringent and several union petitioners (Unions)
    believe OSHA improperly failed to make the Rule stringent
    enough.
    Industry petitioned for review of five issues: (1) whether
    substantial evidence supports OSHA’s finding that limiting
    workers’ silica exposure to the level set by the Rule reduces a
    significant risk of material health impairment; (2) whether
    substantial evidence supports OSHA’s finding that the Rule is
    technologically feasible for the foundry, hydraulic fracturing,
    1
    The OSHA rule at issue regulates only respirable crystalline
    forms of silica. See 
    29 C.F.R. § 1910.1053
    (a)(1). For ease of
    reference, we use “silica” as a shorthand for respirable crystalline
    silica.
    4
    and construction industries; (3) whether substantial evidence
    supports OSHA’s finding that the Rule is economically feasible
    for the foundry, hydraulic fracturing, and construction
    industries; (4) whether OSHA violated the Administrative
    Procedure Act (APA) in promulgating the Rule; and (5)
    whether substantial evidence supports two ancillary provisions
    of the Rule—one that allows workers who undergo medical
    examinations to keep the results confidential from their
    employers and one that prohibits employers from using dry
    cleaning methods unless doing so is infeasible. We reject all of
    Industry’s challenges.
    The Unions petitioned for review of two parts of the Rule:
    (1) the requirement that medical surveillance for construction
    workers be provided only if the employee has to wear a
    respirator for 30 days for one employer in a one-year period;
    and (2) the absence of medical removal protections. We reject
    the Unions’ challenge to the construction standard’s 30-day
    trigger for medical surveillance. We conclude that OSHA
    failed to adequately explain its decision to omit medical
    removal protections from the Rule and remand for further
    consideration of the issue.
    I.   BACKGROUND
    The Occupational Safety and Health Act (OSH Act)
    authorizes the Secretary of Labor (Secretary) to “promulgate,
    modify, or revoke any occupational safety or health standard,”
    
    29 U.S.C. § 655
    (b), by requiring conditions or the adoption of
    practices, means, or methods “reasonably necessary or
    appropriate to provide safe or healthful employment and places
    of employment,” 
    id.
     § 652(8). If the standard applies to toxic
    materials or harmful physical agents, the Secretary “shall set
    the standard which most adequately assures, to the extent
    feasible, on the basis of the best available evidence, that no
    5
    employee will suffer material impairment of health or
    functional capacity even if such employee has regular exposure
    to the hazard” regulated by the standard “for the period of his
    working life.” Id. § 655(b)(5). The Secretary has delegated
    his authority to OSHA. See 
    72 Fed. Reg. 31,160
     (June 5,
    2007).
    In 1971, OSHA adopted a standard regulating exposure to
    a variety of substances, including silica. Occupational Safety
    and Health Standards; National Consensus Standards and
    Established Federal Standards, 
    36 Fed. Reg. 10,466
     (May 29,
    1971). The 1971 rule established a permissible exposure limit
    (PEL)—a time-weighted average of a worker’s exposure
    during a workday—of 100 micrograms per cubic meter
    (µg/m3) in general industry 2 and 250 µg/m3 in the construction
    industry. See 81 Fed. Reg. at 16,294. In the 1990s, OSHA
    studied the efficacy of the 1971 rule regarding silica-related
    health effects in the workplace and concluded a new rule was
    needed. See id. at 16,295.
    In 2016, OSHA promulgated its final Silica Rule. 
    81 Fed. Reg. 16,285
    . The Rule lowers the PEL to 50 µg/m3 for all
    covered industries, including as particularly relevant here, the
    foundry, hydraulic fracturing, brick, and construction
    industries. See 
    29 C.F.R. §§ 1910.1053
    (c), 1926.1153(d)(1).
    Employers must assess silica exposure levels in the workplace
    (or, for certain construction industry tasks, adopt specific “safe-
    harbor” practices) and, if necessary, must implement
    2
    OSHA uses the phrase “general industry” to refer to the
    standard set in 
    29 C.F.R. § 1910.1053
    , which “applies to all
    occupational exposures to respirable crystalline silica, except”
    construction work, agricultural operations, and sorptive-clay
    processing. 
    Id.
     § 1910.1053(a)(1)(i)–(iii). As relevant to the
    petitions, general industry includes the foundry, hydraulic fracturing,
    and brick industries.
    6
    engineering and work practice controls to keep exposures
    below the PEL. Id. §§ 1910.1053(f)(1), 1926.1153(c)(1),
    1926.1153(d)(3)(i). If engineering and work practice controls
    cannot reduce exposures to the PEL, the employer must use
    controls to the extent feasible and provide supplementary
    respirator protections. Id.
    The Silica Rule also establishes various ancillary
    provisions including, again, as relevant here, housekeeping
    requirements and medical surveillance requirements. Under
    the challenged housekeeping provision, employers are
    prohibited from using dry sweeping methods to clean worksites
    if doing so could contribute to employee exposure to silica
    unless wet cleaning methods are infeasible.                 Id.
    §§ 1910.1053(h)(1), 1926.1153(f)(1). Under the challenged
    medical surveillance provisions, employers must provide
    medical screening to silica-exposed workers if certain
    conditions are met. Most of the information from the medical
    examinations,       including      medical       professionals’
    recommendations limiting the employee’s exposure to silica,
    are confidential and cannot be released to the employer unless
    the employee authorizes disclosure. Id. §§ 1910.1053(i)(6),
    1926.1153(h)(6). Finally, the Rule provides no medical
    removal protections to workers whose doctors recommend
    either permanent or temporary removal from silica exposure on
    the job.
    Different compliance dates were established for each
    industry: June 23, 2017 for the construction industry, id.
    § 1926.1153(k); June 23, 2018 for the foundry industry, id.
    § 1910.1053(l); and June 23, 2021 for the hydraulic fracturing
    industry, id.
    7
    II. ANALYSIS
    We first decide Industry’s challenges. In order, we
    address OSHA’s significant risk findings, its technological
    feasibility findings, its economic feasibility findings, the
    procedural regularity of the Rule, and the challenged ancillary
    provisions. The substantive issues are governed by the
    “substantial evidence” standard, 
    29 U.S.C. § 655
    (f), under
    which we require OSHA to “identify relevant factual evidence,
    to explain the logic and the policies underlying any legislative
    choice, to state candidly any assumptions on which it relies,
    and to present its reasons for rejecting significant contrary
    evidence and argument,” United Steelworkers of America v.
    Marshall (Lead I), 
    647 F.2d 1189
    , 1207 (D.C. Cir. 1980). The
    APA governs the procedural challenge to ensure the Rule is not
    promulgated “without observance of procedure required by
    law.” 
    5 U.S.C. § 706
    (2)(D).
    We then turn to the Unions’ challenges and address the 30-
    day medical surveillance trigger in the construction standard
    and the lack of medical removal protections in the general
    industry standard. Where the Unions have failed to identify
    evidence that their proposals would be feasible and generate
    more than a de minimis benefit to worker health, we reject
    them. See Building & Construction Trades Department, AFL-
    CIO v. Brock (Asbestos), 
    838 F.2d 1258
    , 1271 (D.C. Cir. 1988).
    Where the Unions have met this initial burden, we ask whether
    OSHA has supported its decision with substantial evidence and
    otherwise engaged in reasoned decisionmaking.
    A. SIGNIFICANT RISK
    Before OSHA promulgates any permanent health or safety
    standard, it must make a “threshold finding” that “it is at least
    more likely than not that long-term exposure” to the regulated
    substance at current exposure levels “presents a significant risk
    8
    of material impairment” that “can be eliminated or lessened by
    a change in practices.” Industrial Union Department, AFL-
    CIO v. American Petroleum Institute (Benzene), 
    448 U.S. 607
    ,
    642, 653 (1980) (plurality). 3 The Supreme Court has provided
    the guidepost that OSHA follows: a one-in-a-thousand risk that
    exposure to the regulated substance will be fatal can reasonably
    be considered significant but a one-in-a-billion risk is likely not
    significant. 
    Id.
     at 655–56.
    OSHA must support its significant risk finding with
    substantial evidence. 
    Id. at 653
    . Although it must rely on a
    “body of reputable scientific thought” when assessing risk, 
    id. at 656
    , OSHA does not have to “calculate the exact probability
    of harm” or support its finding “with anything approaching
    scientific certainty,” 
    id.
     at 655–56. OSHA is entitled to “some
    leeway” when its “findings must be made on the frontiers of
    scientific knowledge.” 
    Id. at 656
    . We “do not reweigh the
    evidence and come to our own conclusion[s]; rather, we assess
    the reasonableness of OSHA’s conclusion.” Public Citizen
    Health Research Group v. Tyson (Ethylene Oxide), 
    796 F.2d 1479
    , 1495 (D.C. Cir. 1986).
    In promulgating the Silica Rule, OSHA conducted a
    Quantitative Risk Assessment in which it reviewed
    toxicological, epidemiological, and experimental studies about
    the adverse health effects of silica exposure. 81 Fed. Reg. at
    16,380. OSHA quantified the excess risk 4 of silica-related
    3
    Although Benzene commanded only a plurality of the Court,
    a majority of the Court endorsed the significant risk requirement in
    a later case. See National Maritime Safety Association v. OSHA,
    
    649 F.3d 743
    , 750 n.8 (D.C. Cir. 2011) (citing American Textile
    Manufacturers Institute, Inc. v. Donovan, 
    452 U.S. 490
    , 506 (1981)).
    4
    Excess risk identifies the risk “solely attributable” to silica
    exposure, 81 Fed. Reg. at 16,372, by “factoring in the probability of
    surviving to a particular age assuming no exposure to [silica] and
    9
    health effects assuming exposure over a working life (45 years)
    to various levels of silica, including the original general
    industry PEL of 100 µg/m3, the original construction PEL of
    250 µg/m3, and the new PEL of 50 µg/m3. Id. at 16,300.
    OSHA concluded that silica exposure significantly “increases
    the risk of” four adverse health effects: silicosis and other non-
    malignant respiratory disease (NMRD) mortality, lung cancer
    mortality, silicosis morbidity, and renal disease mortality. Id.
    at 16,300, 16,386–87. OSHA also concluded that the risks at
    50 µg/m3—the new PEL—are lower than the risks at the
    original PELs of 100 µg/m3 and 250 µg/m3. Id. at 16,300. In
    total, OSHA estimated that the Silica Rule will prevent 642
    deaths and 918 cases of silica-related disease each year. Id. at
    16,399. 5
    Industry challenges OSHA’s significant risk findings in
    three ways. First, Industry attacks two parts of OSHA’s risk-
    assessment methodology. Second, it challenges OSHA’s
    findings on each of the four individual health risks. Finally,
    Industry challenges OSHA’s decision to include the brick
    industry within the scope of the Rule. We reject each
    challenge.
    1.   OSHA’s Methodology
    Industry challenges two components of OSHA’s risk-
    assessment methodology: its no-threshold assumption and its
    failure to account for a dose-rate effect. We uphold OSHA’s
    decisions on both.
    given the background probability of dying from any cause at or
    before that age,” id. at 16,385.
    5
    The number of deaths and cases of silica-related disease
    resulting from each of the individual adverse health effects is
    discussed infra.
    10
    First, Industry challenges OSHA’s use of no-threshold
    exposure-response models in its risk assessments for silicosis
    and lung cancer. 81 Fed. Reg. at 16,351. The no-threshold
    concept means there is no exposure level below which workers
    would not be expected to develop adverse health effects. Id.
    OSHA did not definitively find that no threshold exists.
    Instead, it found that if a threshold exists it does so below the
    PEL, which justified its use of a no-threshold model. OSHA
    supported its selection of the PEL with studies showing that
    risks of lung cancer exist at 36 µg/m3 and 10 µg/m3, levels
    lower than the PEL. Id. at 16,351, 16,356. To OSHA, the
    studies showing risks below the PEL support its conclusion that
    any threshold, if it exists, does so below the PEL. See id. at
    16,351 (“As 36 µg/m3 is well below the previous industry PEL
    of 100 µg/m3 and below the final PEL of 50 µg/m3, the . . .
    study showed no evidence of an exposure-response threshold
    high enough to impact OSHA’s choice of PEL.”). Industry, in
    contrast, points to studies it claims not only show a threshold
    exists but also show a threshold exists above the PEL. OSHA
    rejected Industry’s argument because the contrary studies used
    non-reactive and poorly soluble particles—which silica is
    not—and therefore the “findings regarding” the particles
    “[cannot] be extrapolated to crystalline silica.” Id. at 16,349.
    OSHA acknowledged “there is considerable uncertainty” about
    whether a threshold exists but found that “the weight of
    evidence supports the view that, if there is a threshold,” it is
    “likely lower than the” PEL. Id. at 16,351.
    OSHA’s no-threshold assumption is supported by
    substantial evidence. Although Industry claims OSHA’s
    position is inconsistent with common sense and “mounting
    judicial skepticism” of no-threshold models, citing to several
    district court and state court cases disapproving a no-threshold
    approach, Industry Br. at 28–29, OSHA’s position is in line
    with our precedent. In Ethylene Oxide, we upheld a no-
    11
    threshold model based on OSHA’s having found evidence of
    adverse health effects at levels of exposure to ethylene oxide
    below the established PEL, then extrapolating that evidence to
    assume no threshold of ethylene oxide exposure existed below
    which risks did not exist and rejecting two contrary comments
    that purportedly showed a threshold did exist. 
    796 F.2d at 1500
    . As in Ethylene Oxide, Industry presents, and urges us
    to adopt, “one side of the debate.” 
    Id.
     But OSHA has
    explained why it rejected Industry’s side of the debate,
    presented the other side of the debate, and supported it with
    evidence from which a reasonable conclusion could be made,
    as OSHA did here, that no threshold of safe exposure to silica
    exists. We cannot “choose a particular side as the ‘right’ one”
    in a scientific dispute. 
    Id.
     Accordingly, OSHA’s no-
    threshold assumption satisfies our substantial evidence test.
    Second, Industry challenges OSHA’s decision not to
    include a dose-rate effect in the model, which means OSHA
    assessed health risks based on the cumulative amount of silica
    exposure without accounting for the intensity of exposures.
    81 Fed. Reg. at 16,375. OSHA took its position “because each
    of the key . . . studies” OSHA relied on used cumulative
    exposure as the only metric. Id. at 16,374–75. Multiple
    commenters supported the notion that “cumulative exposure is
    a reasonable and practical choice” and that cumulative
    exposure “is often the best predictor of chronic disease.” Id.
    at 16,375. Competing commenters argued that OSHA’s risk
    assessment should account for the intensity of exposures. Id.
    Industry relied on studies showing that not accounting for a
    dose-rate effect “could overestimate risk at lower
    concentrations.” Id. The studies supporting Industry’s
    position, however, largely observed an intensity-based effect at
    500 µg/m3 and 2,000 µg/m3, exposure levels so “far above the
    previous PEL,” id. at 16,395, that OSHA determined the
    12
    studies were of little use to the “exposure range of interest”—
    25 to 500 µg/m3, id. at 16,376.
    In Ethylene Oxide, we upheld OSHA’s decision not to
    include a dose-rate effect in its model when faced with
    “competing technical opinions” about whether the amount or
    the intensity of ethylene oxide exposure mattered more.
    Ethylene Oxide, 
    796 F.2d at 1504
    . OSHA did the same in its
    Silica Rule: it took competing evidence, favored one side, and
    explained the reasons for its decision. We “cannot expect
    OSHA to [locate and use] absolutely conclusive studies on
    these difficult medical issues” and we must uphold OSHA’s
    choice, even in the face of “controverted” evidence, if it falls
    within a “zone of reasonableness.” Lead I, 647 F.2d at 1253
    (quoting Hercules, Inc. v. EPA, 
    598 F.2d 91
    , 107 (D.C. Cir.
    1978)). We believe OSHA’s conclusions on handling the
    purported dose-rate effect are reasonable. “[C]ourts cannot
    interfere with reasonable interpretations of equivocal
    evidence,” Ethylene Oxide, 
    796 F.2d at 1505
    , and therefore we
    do not interfere here.
    2.   Adverse Health Effects
    As noted earlier, OSHA concluded that long-term silica
    exposure above the PEL presents a significant risk of four
    discrete adverse health effects: (1) silicosis and NMRD
    mortality; (2) lung cancer mortality; (3) silicosis morbidity; and
    (4) renal disease mortality. 81 Fed. Reg. at 16,300, 16,386–
    87. Industry challenges OSHA’s findings as to all four.
    Industry acknowledged at oral argument that, to prevail, it
    would have to show none of the discrete findings is supported
    by substantial evidence. We address each in turn. We
    conclude OSHA’s significant risk findings as to the first three
    adverse health effects are supported by substantial evidence,
    which supports OSHA’s overall finding of a significant risk.
    13
    We do not reach OSHA’s finding with respect to renal disease
    mortality.
    i.   Silicosis or Non-Malignant Respiratory Disease
    Mortality
    Silicosis is a progressive, irreversible lung disease caused
    by the inflammatory effects of silica in the lungs. OSHA
    found that silica exposure at the original PEL of 100 µg/m3
    created an excess risk of silicosis mortality for 11 in 1,000
    workers that would be reduced to 7 in 1,000 workers at the
    Rule’s PEL of 50 µg/m3. 81 Fed. Reg. at 16,303, 16,312.
    Other NMRD caused by silica exposure include emphysema,
    chronic obstructive pulmonary disease, and chronic bronchitis.
    Id. at 16,304. OSHA found that silica exposure at the 100
    µg/m3 PEL created an excess risk of NMRD mortality
    (including silicosis mortality) for 85 in 1,000 workers that
    would be reduced to 44 in 1,000 workers at the Rule’s PEL of
    50 µg/m3. Id. at 16,303. Both Industry and the Chambers
    Intervenors 6 challenge OSHA’s findings on silicosis and
    NMRD mortality.
    To support its findings on silicosis and NMRD mortality,
    OSHA relied on two studies: the Mannetje study, which
    showed a statistically significant association between silicosis
    mortality and cumulative exposure to silica, and the Park study,
    which quantified the relationship between silica exposure and
    NMRD mortality. Id. at 16,317. Industry’s objections to
    OSHA’s conclusions primarily attack the reliability of the Park
    study. Industry claims the Park study (1) focused on workers
    with cumulative exposure levels far above what workers
    6
    The Chamber of Commerce of the United States, the State
    Chamber of Oklahoma, and the Greater North Dakota Chamber of
    Commerce (collectively, Chambers) intervened on behalf of
    Industry.
    14
    typically faced under the original PEL and (2) produced results
    that were likely skewed by smoking because the study had
    smoking data for only one-half of the studied workers.
    In its rulemaking, OSHA addressed both criticisms. On
    the first point, OSHA acknowledged “some uncertainty in
    using models heavily influenced by exposures above the
    previous PEL” but noted that the average cumulative exposure
    of the studied workers was “lower than what the final rule
    would permit over 45 years of exposure.” Id. at 16,318.
    Accordingly, OSHA “[dis]agree[d] that the Park study should
    be discounted” and instead concluded that the study was both
    relevant and appropriate to rely on. Id. On the second point,
    OSHA acknowledged that “comprehensive smoking data
    would be ideal” but assessed the Park study’s mechanics in
    detail and concluded that the risk estimates were “not likely to
    be exaggerated due to [studied workers’] smoking habits.” Id.
    Under our substantial evidence standard, OSHA has a duty
    to “present its reasons for rejecting significant contrary
    evidence and argument.” Lead I, 647 F.2d at 1207. OSHA
    acknowledged and adequately responded to Industry’s
    criticisms of the Park study. Even if the Park study was
    “flawed in some way,” OSHA is not precluded from relying on
    imperfect evidence so long as it “recognize[s] and account[s]
    for the methodological weaknesses” of the evidence. Ethylene
    Oxide, 
    796 F.2d at 1487
    ; see 
    id. at 1495
     (“While some of
    OSHA’s evidence suffers from shortcomings, such incomplete
    proof is inevitable when the Agency regulates on the frontiers
    of scientific knowledge.”). OSHA did recognize and account
    for the weaknesses of the two studies it relied on here. 7
    7
    Industry did not specifically challenge the Mannetje study in
    its brief so we do not analyze OSHA’s reliance on it.
    15
    The Chambers, meanwhile, present a record of death
    certificates and their listed cause of death that shows silicosis-
    attributed deaths dropped from 1,065 in 1968 (three years
    before the 1971 PEL was implemented) to 123 in 2007. The
    decline, according to the Chambers, shows that the current
    risks are due not to exposure levels at the 1971 PEL but instead
    are due to pre-1971 exposures or exposures occurring in
    violation of the 1971 PEL. Thus, the Chambers argue, the
    1971 rule is working and there is no need for a new one.
    But here again, OSHA adequately explained why it
    rejected this evidence. First, OSHA concluded that the death
    certificate data underreported risks after one commenter found
    that silicosis was listed as the cause of death for only 14 percent
    of people with confirmed silicosis. 81 Fed. Reg. at 16,328.
    Second, the death certificate data “d[id] not include
    information about exposure[]” levels for those who died as a
    result of silicosis, which made the data “inadequate and
    inappropriate for” setting a standard regulating silica at
    particular exposure levels. Id. at 16,326. Indeed, the agency
    that compiled and analyzed the death certificate data testified
    that relying on the death certificates to show no significant risk
    exists would be a “misuse” of the data. Id.
    Moreover, OSHA responded directly to the Chambers’
    arguments that the death certificate data showed the risks of
    silica exposure are no longer significant.                    OSHA
    acknowledged that silicosis-related deaths have dropped since
    1968 but pointed to evidence showing that the decline leveled
    off at approximately 90 to 180 deaths per year since 2000. Id.
    at 16,324. This evidence “suggest[s] that the number of
    silicosis deaths . . . may be stabilizing,” id., which also suggests
    that the significant risk of silicosis mortality would not
    disappear if OSHA simply let the 1971 PEL run its course, as
    Industry argued, id. at 16,325. OSHA also pointed to
    16
    evidence showing that the decline in silicosis-related deaths
    tracks the decline in high-exposure jobs as much as it tracks
    improved working conditions, further suggesting that OSHA
    “still h[as] work to do” to make silica exposure safe. Id. at
    16,325–26. Thus, although OSHA agreed that the death
    certificate data was “useful for providing context and an
    illustration of a significant general trend in the reduction of
    deaths associated with silicosis over the past four to five
    decades,” the “limited and incomplete” data made reliance on
    the death certificates “inappropriate.” Id. at 16,330. OSHA
    “described in some detail [its] reasons for choosing between
    competing alternatives.”       Asbestos, 
    838 F.2d at 1266
    .
    Accordingly, OSHA has met its burden to identify the evidence
    it relied on and explain why it rejected contrary evidence.
    ii. Lung Cancer Mortality
    OSHA found that silica exposure at the 100 µg/m3 PEL
    created an excess risk of lung cancer mortality equal to 11 to
    54 deaths per 1,000 workers that would be reduced to an excess
    risk of 5 to 23 deaths per 1,000 workers at the 50 µg/m3 PEL.
    81 Fed. Reg. at 16,338. Industry argues the conclusion hinges
    on OSHA’s unsupported assumption that silica exposure
    directly increases the risk of lung cancer in the absence of
    silicosis. That is, if the risk of lung cancer depends on pre-
    existing silicosis, then silica exposure alone does not create an
    independent risk of lung cancer.
    Industry points to evidence that asserts the association
    between silicosis and lung cancer is “more compelling” than
    the association between silica exposure and lung cancer. Joint
    Appendix (J.A.) 3027. But the mere suggestion in some
    evidence that silicosis is a necessary precursor of lung cancer
    does not bind the agency. See Ethylene Oxide, 
    796 F.2d at 1504
     (noting that suggestive statements “do not amount to a
    17
    scientific certainty binding on the agency”). Meanwhile,
    OSHA also cites to numerous studies that show silica exposure
    can lead directly to lung cancer. 81 Fed. Reg. at 16,309
    (recapping and summarizing findings). As one commenter
    put it, the literature OSHA relied on shows “silica has been
    established as a cause of lung cancer.” J.A. 7815. We lack
    the technical expertise to second-guess OSHA’s judgment
    when it “review[ed] all sides of the issue and reasonably
    resolve[d] the matter.” Ethylene Oxide, 
    796 F.2d at 1500
    .
    We do not second-guess OSHA’s conclusions here.
    Industry specifically challenges OSHA’s decision to give
    weight to a 2004 Attfield and Costello study, which showed
    there is an association between silica exposure and lung cancer,
    instead of a 2011 Vacek study showing there is no such
    association. 81 Fed. Reg. at 16,338. Industry provides a
    laundry list of reasons why it believes the Vacek study is better:
    it is more recent, covered more workers, covered more years,
    and used more detailed information. But OSHA explained its
    reasons for rejecting the Vacek study. Among them: the
    Vacek study found an unexplained significant excess risk of
    lung cancer that called into question all of its results and had a
    low risk estimate for a particular type of worker (channel bar
    operators) that OSHA concluded had major consequences for
    the entire exposure analysis. Id. at 16,335–37. Moreover,
    OSHA provided affirmative reasons for choosing the Attfield
    and Costello study. Most importantly, OSHA reasoned, that
    study accounted for a healthy worker survivor effect—the
    tendency of healthy workers to remain in the workforce longer
    than ill workers and therefore face more exposure than ill
    workers, which “may” make the “risk of disease at higher
    exposures” improperly “appear to be constant or decrease”—
    but the Vacek study did not assess the healthy worker survivor
    effect. Id. at 16,336. “We have then, at worst, the ordinary
    situation of controverted evidence, in which we must defer to
    18
    the reasonable and conscientious interpretations of the
    agency.” Lead I, 647 F.2d at 1258.
    iii. Silicosis Morbidity
    To support its finding of a significant risk of silicosis
    morbidity, OSHA relied on five studies that showed an excess
    risk between 60 and 773 cases of silicosis morbidity per 1,000
    workers at a level of 100 µg/m3 that would be reduced to an
    excess risk between 20 and 170 cases of silicosis morbidity per
    1,000 workers at a level of 50 µg/m3. 81 Fed. Reg. at 16,317.
    The variance among studies, according to Industry, “suggests
    that none of [the studies] is a reliable guide to a correct
    quantification” of exposures and therefore none of the studies
    can support a finding of a significant risk of silicosis morbidity.
    J.A. 3368. OSHA concluded the results of the five studies did
    not “differ remarkably,” 81 Fed. Reg. at 16,321, which Industry
    asserts is “arbitrary and capricious reasoning,” Industry Br. at
    39.
    In the rulemaking OSHA responded to critiques against
    the individual studies upon which OSHA relied. See 81 Fed.
    Reg. at 16,320–22. OSHA also responded to critiques of the
    variance among the studies, albeit in less detailed fashion, and
    concluded that the risk estimates among the studies “are in
    reasonable agreement.”          Id. at 16,322.           OSHA’s
    reconciliation of the data’s variance is not airtight. A more
    important question, however, is whether the studies constitute
    substantial evidence supporting OSHA’s finding of a
    significant risk of silicosis morbidity at the initial PEL that is
    reduced at the Rule’s PEL. They do.
    The variance in results may show uncertainty as to the
    precise amount of the risk of silicosis morbidity. Maybe it
    falls closer to 60 cases per 1,000 workers at 100 µg/m3; maybe
    it falls closer to 773 per 1,000. Maybe it falls closer to 20
    19
    cases per 1,000 workers at 50 µg/m3; maybe it falls closer to
    170. “While each study individually may not be a model of
    textbook scientific inquiry,” we assess, again, the “cumulative
    evidence” OSHA relied on. Ethylene Oxide, 
    796 F.2d at 1489
    .
    Even assuming the actual amount of risk is closer to the low
    end, a “reasonable person could draw from this evidence the
    conclusion that exposure to” silica presents a significant risk of
    silicosis morbidity. 
    Id.
     “Even if a reasonable person could
    also draw the opposite conclusion, we must uphold the
    agency’s findings.” 
    Id.
     We conclude, then, that OSHA’s
    conclusion that exposure to silica presents a significant risk of
    silicosis morbidity is supported by substantial evidence.
    iv. Renal Disease Mortality
    OSHA concluded that the excess risk of renal disease
    mortality would drop from 39 deaths per 1,000 workers at the
    100 µg/m3 PEL to 32 deaths per 1,000 workers at the 50 µg/m3
    PEL. 81 Fed. Reg. at 16,342. OSHA relied on a single
    pooled study that provided “considerably less data” compared
    to the studies of the other disease endpoints. Id. at 16,345.
    OSHA rejected numerous other studies that showed no risk of
    renal disease. Id. at 16,344–45. Industry argues that OSHA
    lacked substantial evidence to support a finding of a significant
    risk of renal disease mortality and failed to explain its
    resolution of conflicting evidence.
    OSHA acknowledged in the rulemaking that the evidence
    supporting its finding regarding renal disease mortality was
    “less robust” than the evidence supporting its findings for other
    silica-related health effects. Id. at 16,345. OSHA defended
    its position with a single footnote in its brief. We note
    OSHA’s concession that the evidence is weak; if OSHA had
    relied solely on the risk of renal disease mortality to support the
    20
    Silica Rule, its decision may well have been unsupported by
    substantial evidence.
    But we need not and do not decide whether OSHA
    supported its renal disease findings with substantial evidence
    because OSHA’s findings with respect to silicosis and NMRD
    mortality, lung cancer mortality, and silicosis morbidity are
    sufficient to uphold the requisite threshold finding of a
    significant risk of material health impairment at the 100 µg/m3
    PEL that will be reduced at the new PEL. See National
    Maritime Safety Association v. OSHA, 
    649 F.3d 743
    , 752 n.11
    (D.C. Cir. 2011) (upholding OSHA’s significant risk finding
    where OSHA relied on four contributors to the risk but one was
    flawed; if OSHA “relied on [the flawed] factor alone, its
    significant risk determination might well have been arbitrary
    and capricious” but the presence of the other substantiated
    factors sufficiently supported OSHA’s significant risk finding).
    And Industry does not show that any weakness with respect to
    OSHA’s renal disease findings infected OSHA’s findings
    regarding the other adverse health effects such that the entire
    significant risk conclusion is undermined. Accordingly, we
    do not decide the renal disease issue because OSHA, through
    its supported findings on the other three adverse health effects,
    has met its burden to show that the Silica Rule regulates a
    significant risk of material harm.
    3.   Brick Industry
    Industry argues OSHA should have excluded the brick
    industry from the scope of the Silica Rule because OSHA did
    not have substantial evidence to find a significant risk of
    material harm in the brick industry. OSHA pins its findings
    on one study (the Love study) that surveyed brick plant
    workers. 81 Fed. Reg. at 16,378. The Love study reported
    that 1.4 percent—a rate below OSHA’s risk estimates in other
    21
    industries but exceeding Benzene’s general 0.1 percent
    benchmark—of brick workers had small abnormalities in x-
    rays, which the authors said were “most likely” silicosis. Id.
    Industry makes three arguments to contest the findings based
    on the Love study.
    First, Industry argues that OSHA used the Love study
    when it wanted to and did not use the Love study when it did
    not want to. Specifically, OSHA found the Love study
    showed a significant risk of silicosis but declined to include the
    Love study in the group of studies that formed the basis of
    OSHA’s silicosis morbidity quantitative risk assessment. See
    id. at 16,377–78. If OSHA exhibits “apparently inconsistent
    handling of the evidence available to it,” OSHA cannot be said
    to have relied on the best available evidence. See American
    Iron & Steel Institute v. OSHA (Lead II), 
    939 F.2d 975
    , 1009
    (D.C. Cir. 1991) (per curiam) (rejecting OSHA’s conclusions
    when it criticized one industry study yet relied on another study
    with the same flaws).
    But OSHA explained its rationale. The Love study
    excluded retired workers and had little follow-up data on the
    workers it included. 81 Fed. Reg. at 16,378. These two data
    pieces are “extremely important” to fully quantify risks of
    silicosis morbidity because “silicosis typically develops slowly
    and becomes detectable [decades after] a worker’s first
    exposure.” Id. at 16,377–78. Without the two data pieces,
    the Love study did not meet OSHA’s “rigorous standards used
    in the studies on which OSHA’s [silicosis morbidity] risk
    assessment relies” and therefore could not be included. Id. at
    16,377. But the lack of the two data points did not render the
    Love study meaningless—if anything, OSHA reasoned, the
    failure to study workers at later stages of their career, when the
    latent effects of silica exposure are more likely to manifest,
    meant the Love study “underestimated” the risk of silicosis to
    22
    brick industry workers. Id. at 16,378. Moreover, the Love
    study was the only study specific to the brick industry that used
    exposure-response information, making it the “highest-
    quality” study for ascertaining risks. Id. As one commenter
    testified, the Love study was the “only sensible study to be used
    for setting an exposure limit . . . in brick manufacturing.” Id.
    OSHA, then, explained its reasoning and supported it with
    substantial evidence.
    Second, Industry argues that even if the Love study is a
    credible source, OSHA’s risk estimates in other industries and
    for other disease endpoints (between 2 and 17 percent) at the
    PEL are greater than the risk estimates for the brick industry
    (1.4 percent), and therefore OSHA should have let the brick
    industry’s risks remain unaltered.              But Industry
    misunderstands the legal standard. The mere fact that the
    brick industry faces a lower risk than other industries does not
    mean the brick industry’s risks are not significant. And the
    1.4 percent risk quantified by the Love study surpasses the
    Supreme Court’s 0.1 percent benchmark. Benzene, 
    448 U.S. at
    655–56.
    Industry finally argues that OSHA’s different treatment of
    the brick industry and the sorptive minerals industry is arbitrary
    and capricious. According to Industry, the substances in both
    industries have chemical properties that reduce the toxicity of
    silica (which would reduce the health risks of exposure to
    silica) yet the Rule includes the brick industry but not the
    sorptive minerals industry. OSHA explained its decision in
    the preamble to the rule. The evidence for the sorptive
    minerals industry was unclear and thus insufficient to conclude
    a significant risk exists. 81 Fed. Reg. at 16,379–80. In
    contrast, the evidence in the brick industry—the Love study,
    primarily—showed there is a significant risk. Id. at 16,377–
    78. Even if brick clay and sorptive minerals have similar
    23
    chemical properties that reduce the toxicity of silica within
    those compounds, OSHA found the evidence as it existed in the
    record was not similar enough to treat them similarly. Id.
    OSHA’s position is supported by substantial evidence and a
    reasonable explanation, and therefore we uphold the inclusion
    of the brick industry in the Silica Rule.
    B. TECHNOLOGICAL FEASIBILITY
    This court has interpreted the OSH Act’s requirement that
    OSHA health standards protect workers “to the extent
    feasible,” 
    29 U.S.C. § 655
    (b)(5), to include “two types of
    feasibility,” namely, “technological and economic.” Lead I,
    647 F.2d at 1264. Our standard of review narrowly cabins our
    consideration of OSHA’s finding of technological feasibility.
    Specifically, we must ensure only that OSHA found its
    standard feasible and supported that finding with substantial
    evidence.
    “To establish technological feasibility, OSHA, after
    consulting the ‘best available evidence,’ must prove ‘a
    reasonable possibility that the typical firm will be able to
    develop and install engineering and work practice controls that
    can meet the [standard] in most of its operations.’” Lead II,
    
    939 F.2d at 980
     (quoting Lead I, 647 F.2d at 1272). OSHA
    need not show with certainty that all firms will be able to meet
    the new standard in all operations. If “‘only the most
    technologically advanced plants in an industry have been able
    to achieve [the standard]—even if only in some of their
    operations some of the time,’ then the standard is considered
    feasible for the entire industry.” Id. (alteration in original)
    (quoting Lead I, 647 F.2d at 1264).
    As with its finding of significant risk, OSHA must support
    its finding of technological feasibility with substantial
    evidence. Substantial evidence does not require absolute
    24
    “certainty.” Id. Where OSHA regulates on the frontiers of
    scientific knowledge, it is bound to confront inconsistency and
    uncertainty. But the mere “possibility of drawing two
    inconsistent conclusions from the evidence does not prevent
    [the] agency’s finding from being supported by substantial
    evidence.” American Textile Manufacturers Institute, Inc. v.
    Donovan (Cotton Dust), 
    452 U.S. 490
    , 523 (1981) (quoting
    Consolo v. FMC, 
    383 U.S. 607
    , 620 (1966)). So long as
    “OSHA makes reasonable predictions based on ‘credible
    sources of information’ (e.g., data from existing plants and
    expert testimony), then the court should defer to OSHA’s
    feasibility determinations.” Lead II, 
    939 F.2d at 980
    .
    Where OSHA has demonstrated technological feasibility
    for the typical firm in most operations and has supported that
    finding with substantial evidence, it has satisfied its burden and
    we must defer to its conclusions. To mount a successful attack
    on OSHA’s feasibility finding, then, challengers must do more
    than suggest that compliance will be infeasible for some firms
    or in “a few isolated operations.” 
    Id.
    In the robust process leading up to the promulgation of the
    silica rule, OSHA found that the rule would be technologically
    feasible based on a thorough consideration of available sources
    of information. For general industry and construction, OSHA
    identified job categories that involve silica exposure and
    developed profiles showing current exposure levels. OSHA
    then identified the individual jobs for which additional controls
    are required to comply with the new PEL, and identified
    available controls that would reduce exposure below the new
    PEL. 81 Fed. Reg. at 16,433–34.
    OSHA concluded that achieving the new PEL is
    technologically feasible for 87 out of 90 job categories
    considered in general industry—including 36 categories in the
    25
    foundry industry, all of which were deemed feasible—and 19
    of 23 tasks considered in construction. Id. at 16,454–55,
    16,459. On this basis, OSHA found that there was a
    reasonable possibility that the new standard could be achieved
    by the typical employer in most operations and was thus
    technologically feasible.
    In performing its analysis, OSHA relied on data from a
    variety of sources, including reports from OSHA inspections,
    National Institute for Occupational Safety and Health (NIOSH)
    reports, site visits conducted by a contractor, data from external
    stakeholders, and a variety of studies looking at the
    effectiveness of various controls. OSHA also considered and
    responded to testimony and comments submitted to the
    rulemaking record.
    With our highly deferential standard of review and
    OSHA’s process in mind, we now turn to Industry’s objections.
    Industry challenges OSHA’s feasibility findings in only three
    industries: foundries, hydraulic fracturing, and construction.
    While Industry identifies sundry examples of infeasibility for
    certain firms or in certain operations, their objections do not
    collectively undermine OSHA’s overall finding of feasibility
    for the typical firm in most operations nor do they meaningfully
    call into question the evidence on which OSHA relied.
    1. Foundries
    Industry disputes OSHA’s finding of technological
    feasibility on two grounds: that variability in exposure levels
    makes compliance infeasible; and that OSHA did not rely on
    the best available evidence.
    On the issue of exposure variability, Industry contends that
    because of the dynamic and unpredictable nature of silica
    exposure, firms must strive to attain an exposure level well
    26
    below the new PEL to ensure compliance with certainty. This
    argument runs headlong into our standard of review:
    “Feasibility of compliance turns on whether exposure levels
    . . . can be met in most operations most of the time; therefore,
    it is the routine exposure levels that determine feasibility, and
    atypical outliers cannot invalidate a feasibility finding.” Lead
    II, 
    939 F.2d at 990
    .
    Industry’s focus on whether all foundries can always meet
    the new standard with certainty is thus beside the point. The
    relevant question is whether OSHA has shown that the typical
    firm can meet the standard in most operations. OSHA has
    done just that. It pointed to data—including over 1,000
    samples from nearly 100 foundries—supporting its feasibility
    finding. Indeed, a study by the American Foundry Society,
    which Industry itself relies on, shows that the new PEL is
    already being met in most foundry job categories. OSHA
    further recognized that variability can be smoothed through
    consistent use of engineering controls. And OSHA expressly
    contemplates flexible enforcement to accommodate
    unexpected swings in exposure levels, an approach this court
    has approved in prior feasibility determinations. 81 Fed. Reg.
    at 16,459; see Lead II, 
    939 F.2d at 991
    .
    Industry may well be right that exposure levels vary
    uncontrollably and unpredictably across the foundry industry
    and within individual firms. That, however, is exactly why
    our standard of review does not require compliance from all
    firms in all operations all of the time; it is designed to permit
    OSHA to regulate in the face of variability and uncertainty.
    And Industry has failed to show that variability in the foundry
    industry undermines OSHA’s finding of feasibility for the
    typical firm in most operations most of the time.
    27
    Industry also challenges the foundry-industry evidence on
    which OSHA relied. The data OSHA considered came from
    a variety of sources including its own visits to worksites,
    enforcement data, and other inspection reports, as well as
    NIOSH reports, state program reports, industrial hygiene
    literature, and survey data from the American Foundry Society,
    all of which supported OSHA’s feasibility finding. Industry,
    insisting that “no two foundries are alike,” contends that OSHA
    ignored the best available evidence, namely, the experiences of
    foundries attempting and failing to comply with the prior
    standard. In particular, Industry singles out sand system
    operators and finishers as two job categories in which
    compliance is infeasible. Industry Br. at 63–65. But
    Industry’s evidence suggests, at most, that compliance will be
    infeasible for some foundries or in some operations. And
    OSHA identifies controls that might be able to achieve
    compliance in the specific foundries and operations that
    Industry identifies. Even assuming that Industry is correct
    that compliance is unachievable in the foundries and operations
    it identifies, such isolated examples of infeasibility are, under
    our standard of review, insufficient to defeat OSHA’s finding
    of feasibility for “the typical” foundry in “most . . . operations.”
    Lead I, 647 F.2d at 1272.
    2. Hydraulic Fracturing
    Because OSHA only recently recognized the risk of silica
    exposure in the hydraulic fracturing industry, available data is
    limited and what data is available shows, unsurprisingly, that
    the vast majority of firms are not yet in compliance with the
    new standard. According to Industry, this evidence shows that
    the new standard is unattainable as there is no evidence of any
    controls reducing exposure below the new PEL.
    28
    But even if sufficient controls do not yet exist, Industry’s
    challenge to OSHA’s feasibility finding nonetheless fails. In
    considering which controls can feasibly be implemented,
    OSHA “is not bound to the technological status quo.” Lead I,
    647 F.2d at 1264. “Because the OSH Act is a ‘technology-
    forcing’ statute, OSHA can also ‘force industry to develop and
    diffuse new technology’” to meet its standard. Lead II, 
    939 F.2d at 980
     (quoting Lead I, 647 F.2d at 1264). So long as
    OSHA “gives industry a reasonable time to develop new
    technology” and “presents substantial evidence that companies
    acting vigorously and in good faith can develop the
    technology,” it can “require industry to meet PELs never
    attained anywhere.” Lead I, 647 F.2d at 1264–65.
    Given the nascent state of silica-control technology in the
    hydraulic fracturing industry, OSHA gave firms five years to
    comply with the new standard. Acknowledging that controls
    have yet to be widely implemented in the industry, OSHA
    identified controls, some currently available and others under
    development, that promise to sufficiently reduce exposure,
    citing to comments from several vendors. 81 Fed. Reg. at
    16,455. In support of the five-year grace period, OSHA relied
    on an industry expert who described significant progress made
    over the prior five years and an inventor of one silica-control
    technology who explained that the technology took only three
    years to develop. Id. at 16,457. Though Industry disagrees
    with OSHA’s forecast of future silica-control developments in
    hydraulic fracturing, the agency’s evidence is more than
    sufficient “to show that modern technology has at least
    conceived some industrial strategies or devices which are likely
    to be capable of meeting the PEL and which the industries are
    generally capable of adopting” in the extended time horizon
    OSHA provided. Lead II, 
    939 F.2d at 1006
     (quoting Lead I,
    647 F.2d at 1266).
    29
    3. Construction
    In assessing the technological feasibility of its rule in the
    construction industry, OSHA relied on the Table 1 safe harbor.
    Under the new rule, if a construction employer implements the
    controls listed on Table 1—applicable to nineteen of twenty-
    three construction tasks—it is freed from its obligation to
    achieve the new PEL. OSHA determined not only that most
    employers would follow Table 1 for most tasks, but also that it
    would be technologically feasible for them to do so given the
    ready availability of Table 1 controls. OSHA also found the
    rule to be technologically feasible for tasks not appearing on
    Table 1. 81 Fed. Reg. at 16,458.
    Industry’s primary challenge to OSHA’s feasibility
    finding is that the Table 1 controls cannot always be
    implemented and sometimes require respiratory protection.
    But even were we to accept Industry’s arguments, these
    isolated exceptions hardly undermine OSHA’s finding of
    feasibility for the typical firm in most operations.
    As to situations where Table 1 controls cannot be
    implemented, Industry focuses on six tasks for which wet
    methods are prescribed, arguing that it is sometimes infeasible
    to introduce water to the work environment, such as for some
    indoor work or in cold-weather environments. Industry Br. at
    98–99. But OSHA adduced evidence showing that employers
    can overcome many of the barriers identified by Industry, for
    example, by using heated water in cold-weather environments.
    81 Fed. Reg. at 16,460. Moreover, even where wet methods
    cannot be implemented, Table 1 functions as just one of two
    paths to compliance: where an employer cannot or elects not to
    follow Table 1, it is free to take the traditional path to
    compliance by implementing controls of its choice to reduce
    exposures below the new PEL. OSHA acknowledged in the
    30
    rulemaking record that such situations may arise and
    contemplated alternative controls that might be implemented.
    Id. at 16,460–61. Even accepting Industry’s arguments that
    compliance for some tasks is infeasible under certain work
    conditions does not overcome OSHA’s finding of feasibility
    for the typical employer in most operations. Because Industry
    argues neither that the typical employer cannot implement wet
    methods nor that such methods are required in most operations,
    it has failed to carry its burden of showing that the use of wet
    methods renders the rule infeasible.
    On the issue of respiratory protection, OSHA assesses
    technological feasibility based on whether firms can “develop
    and install engineering and work practice controls” to meet the
    standard “without relying on respirators.” Lead I, 647 F.2d at
    1272. The fact that “respirators will be necessary in a few . . .
    operations, will not undermine th[e] general presumption in
    favor of feasibility.” Id. Thus the question for our review
    remains whether the need for respirators is so widespread as to
    undermine OSHA’s finding of feasibility for the typical firm in
    most operations.
    OSHA, however, contemplates only limited respirator use.
    Industry argues that “one-third of [Table 1 tasks] require some
    form of respiratory protection when the task is performed for
    just over four hours,” which is “significant and . . . completely
    undercuts OSHA’s claim of technological feasibility.”
    Industry Br. at 95–96. Table 1, however, includes nineteen
    construction tasks, thirteen of which require no respiratory
    protection at all. OSHA Br. at 92 n.56 (explaining that though
    only eighteen tasks are listed, a nineteenth task, performed by
    ground crew assisting equipment operators, is covered by
    Table 1). Certain others, the one-third of tasks to which
    Industry refers, require respirators under only certain
    circumstances, such as when the task is performed indoors or
    31
    for over four hours. See 
    29 C.F.R. § 1926.1153
    (c)(3). And
    OSHA credibly found that most tasks would be performed for
    four hours or less and/or outdoors. 81 Fed. Reg. at 16,724.
    Again, the fact that respiratory protection will be required in
    some operations some of the time fails to satisfy Industry’s
    burden to rebut OSHA’s feasibility finding for the typical firm
    in most operations.
    Industry points to OSHA’s finding that it expects 13% of
    all workers to need some amount of respiratory protection as
    an indication that the rule is infeasible. Specifically, Industry
    argues that in litigation related to OSHA’s Hexavalent
    Chromium rule, the agency rejected respirator use by 9.5% of
    employees as unacceptably high. Industry Reply Br. at 51–52.
    The very language Industry relies on, however, defeats its
    claim. In the Hexavalent Chromium litigation, OSHA stated:
    “While the agency estimated that a total of 9.5% of all
    employees in all application groups would need respirators . . .
    that overall figure did not factor into OSHA’s technological
    feasibility findings . . . .” Public Citizen Health Research
    Group v. OSHA, Nos. 06-1818 and 06-2604, Final Brief for
    Respondents, at 45 (3d Cir. Dec. 14, 2007). There, OSHA
    noted that “respirator use was more than ‘isolated’ where
    almost one third or more of the exposed employees in the
    affected groups would have to use respirators.” Id. Here,
    OSHA’s conclusion that 13% of workers using respirators
    amounts to only “isolated” respirator use neither overwhelms
    its finding of technological feasibility nor conflicts with its
    position in the Hexavalent Chromium litigation. As we have
    explained, OSHA must show only that compliance is feasible
    for the typical firm in most operations—that some respirator
    use may sometimes be needed is not enough to defeat OSHA’s
    finding.
    32
    Even combining the effects of these two issues—the
    sometimes need for respiratory protection and the occasional
    situations where wet methods are infeasible—Industry has
    failed to show that it is infeasible for the typical employer to
    meet the standard in most operations. Some employers may
    be unable to implement the Table 1 controls in all operations—
    though OSHA reasonably explains why there are fewer such
    situations than Industry suggests. And some may have to
    resort to respiratory protection for certain tasks, though, as
    OSHA points out, only for a minority of tasks and only under
    certain circumstances.       But Industry’s identification of
    atypical circumstances in a minority of operations where
    compliance with Table 1 is infeasible falls far short of rebutting
    OSHA’s well-supported finding of feasibility for the typical
    firm in most operations.
    Industry mounts a handful of additional challenges. None
    has merit.
    First, Industry again raises the issue of exposure
    variability. But this argument fails in construction just as it
    failed for the foundry industry: OSHA provided evidence
    suggesting that variability is controllable and, in any event, our
    standard of review is designed to accommodate just such
    variability. Moreover, exposure variability—to the extent it
    presents a problem—is further mitigated in construction, where
    Table 1 provides a path to compliance without any need for
    exposure testing.
    Next, Industry criticizes the evidence upon which OSHA
    relied in determining how the PEL could feasibly be met.
    Specifically, Industry takes issue with OSHA’s reliance on
    short-duration exposure samples and its calculation of an eight-
    hour average assuming no additional exposure during the un-
    sampled portion of the eight-hour period. Industry Br. at 90–
    33
    94. Although few of OSHA’s exposure samples were eight
    hours long, the vast majority (70%) were four hours or longer
    and nearly half (43%) were more than six hours long. 81 Fed.
    Reg. at 16,435. And OSHA considered Industry’s objection
    and adequately justified the no-further-exposure assumption by
    adducing evidence of the intermittent and short-duration nature
    of silica exposure in construction tasks. Id. Moreover,
    OSHA’s assumption aligns with its enforcement practice.
    When OSHA compliance officers collect partial-shift samples
    during an inspection, they calculate eight-hour time-weighted
    average exposures using the same assumption of no further
    exposure during the un-sampled period. The alignment
    between OSHA’s evidence and its enforcement practice
    confirms that any harm to Industry from this assumption is
    more semantic than substantive.
    Finally, Industry disputes OSHA’s finding of feasibility
    for four particular tasks: hole drillers using handheld or stand-
    mounted drills, jackhammering and using other powered
    handheld chipping tools, masonry cutters using stationary
    saws, and mobile crushing machine operators and tenders.
    Industry Br. at 99–105. We have no need to address
    Industry’s arguments as to these tasks, for even were we to
    accept them, Industry would still have failed to rebut OSHA’s
    finding of feasibility in “most operations.” Lead II, 
    939 F.2d at 990
    . In any event, OSHA cited evidence that employers
    could reduce exposure levels for each task using available
    controls. In response, Industry recites a number of by-now
    familiar arguments: that OSHA’s data was inadequate, that the
    tasks are sometimes performed for longer than OSHA assumes,
    and that particular controls (again, wet methods) sometimes
    cannot be implemented.           But OSHA considered and
    responded to each of these objections, making “reasonable
    predictions based on ‘credible sources of information.’” Lead
    II, 
    939 F.2d at 980
     (quoting Lead I, 647 F.2d at 1266). Once
    34
    again, Industry’s insistence that compliance is infeasible for
    some firms in some operations some of the time cannot upend
    our deference to OSHA’s well-supported finding that
    compliance is feasible for the typical firm in most operations.
    C. ECONOMIC FEASIBILITY
    The OSH Act’s requirement that OSHA health standards
    protect workers “to the extent feasible,” 
    29 U.S.C. § 655
    (b)(5),
    also requires OSHA to show that its rule is economically
    feasible, Lead I, 647 F.2d at 1264. As with technological
    feasibility, the scope of our review of OSHA’s economic
    feasibility finding is narrowly circumscribed.
    A rule is economically feasible in a particular industry so
    long as it does not “threaten massive dislocation to, or imperil
    the existence of, the industry.” Id. at 1265. Thus, “[a]
    standard is not infeasible simply because it is financially
    burdensome or even because it threatens the survival of some
    companies within an industry.”           Id. (citation omitted).
    “OSHA is not required to prove economic feasibility with
    certainty, but is required to use the best available evidence and
    to support its conclusions with substantial evidence.” Lead II,
    
    939 F.2d at
    980–81. OSHA must also provide “a reasonable
    estimate of compliance costs and demonstrate a reasonable
    likelihood that these costs will not threaten the existence or
    competitive structure of an industry, even if it does portend
    disaster for some marginal firms.” Lead I, 647 F.2d at 1272.
    “Courts, [moreover], ‘cannot expect hard and precise estimates
    of costs.’” Lead II, 
    939 F.2d at 1006
     (quoting Lead I, 647 F.2d
    at 1266). As before, the mere “possibility of drawing two
    inconsistent conclusions from the evidence” or deriving two
    divergent cost models from the data “does not prevent [the]
    agency’s finding from being supported by substantial
    35
    evidence.” Cotton Dust, 
    452 U.S. at 523
     (quoting Consolo,
    
    383 U.S. at 620
    ).
    Industry does not challenge OSHA’s overall methodology
    for assessing economic feasibility. Instead, it questions the
    evidence on which OSHA relied in the foundry, hydraulic
    fracturing, and construction industries. Industry also gestures
    towards a challenge to OSHA’s findings on the brick industry,
    claiming only that OSHA “cannot adopt a standard that
    imposes very large costs on an industry without producing any
    quantifiable health benefit.” Industry Br. at 130. But
    because OSHA found significant risk in the brick industry, as
    we explained above, and Industry does not otherwise claim
    economic infeasibility, this argument is foreclosed.
    Industry’s economic feasibility arguments, like its
    technological feasibility arguments, raise a host of claims about
    OSHA’s sources that do not collectively undermine the
    evidence OSHA relied on and the conclusions it reached,
    especially in light of our standard of review and the narrow
    scope of Industry’s challenge. In its economic feasibility
    analysis, OSHA developed estimates of the annualized cost of
    compliance for each affected industry—and for small and very
    small employers within each industry—and compared those
    costs against industry revenues and profits. See 81 Fed. Reg.
    at 16,462–582 (describing OSHA’s economic feasibility
    methodology). OSHA explained that “while there is no hard
    and fast rule,” it “generally considers a standard to be
    economically feasible” for an industry where annualized costs
    of compliance are less than one percent of revenue or ten
    percent of profit. Id. at 16,533. OSHA considers this
    benchmark to be “fairly modest,” so costs exceeding the
    threshold do not imply per se infeasibility, but rather serve as a
    trigger for further analysis. Id.
    36
    For each of the industries at issue here—foundries,
    hydraulic fracturing, and construction—OSHA determined
    that costs as a percentage of revenues and profits were below
    the one percent and ten percent thresholds. Id. at 16,536,
    16,538, 16,573. For foundries and construction, these costs
    were well below these benchmarks for all industry subgroups
    considered: even doubling OSHA’s cost estimates in foundries
    and tripling them in construction would only barely trigger the
    thresholds for further inquiry. Id. at 16,538 (showing, among
    subgroups within the foundry industry, costs as a percentage of
    profits of 5.62% at the greatest); id. at 16,573 (showing, among
    subgroups in construction, costs as a percentage of profits of
    3.66% at the greatest). For hydraulic fracturing, compliance
    costs were somewhat nearer OSHA’s thresholds, though still
    below, with costs as a percentage of revenues of 0.56% and
    costs as a percentage of profits of 7.94%. Id. at 16,536
    (assessing hydraulic fracturing as part of the “Support
    Activities for Oil and Gas Operations” industry). OSHA thus
    provided “a reasonable estimate of compliance costs and
    demonstrate[d] a reasonable likelihood that these costs will not
    threaten the existence or competitive structure of an industry.”
    Lead I, 647 F.2d at 1272.
    Industry points out that compliance costs exceed OSHA’s
    threshold for small and very small employers in the hydraulic
    fracturing industry and for very small employers in the foundry
    industry, arguing that this alone renders the rule economically
    infeasible. Industry Br. at 71; see 81 Fed. Reg. at 16,553,
    16,562, 16,564. As explained above, however, exceeding this
    threshold does not in and of itself demonstrate infeasibility;
    instead, it triggers further analysis by OSHA. 81 Fed. Reg. at
    16,533–34.       And the standard for economic feasibility
    contemplates that compliance may be infeasible for a subset of
    firms within an industry, like the small and very small firms at
    issue here. See Lead I, 647 F.2d at 1272 (allowing a finding
    37
    of economic feasibility even where a rule “portend[s] disaster
    for some marginal firms”). Indeed, consistent with its
    understanding of these thresholds as merely triggers for
    additional analysis, OSHA engaged in further inquiry into the
    impact on these firms and reasonably concluded that the Rule
    did not threaten “massive industry dislocation.” See Lead II,
    
    939 F.2d at 980
    .
    1. Foundries
    Industry makes a handful of arguments against OSHA’s
    sources and assumptions, relying primarily on analysis by URS
    Corporation and Environomics showing compliance costs
    much higher than OSHA’s estimates. Industry Br. at 72.
    But, as explained above, our standard of review does not permit
    us to compare competing analyses and decide which we
    prefer—it leaves that responsibility to OSHA. So long as
    OSHA supports its position with substantial evidence, we have
    no need to consider alternatives it might otherwise have
    adopted. We turn, then, to Industry’s challenges to the
    evidence upon which OSHA did rely.
    First, Industry disputes OSHA’s assumption of an even
    apportionment of costs between those required for compliance
    with the prior PEL—which are not attributable to the new
    rule—and those required to further reduce exposure from the
    prior PEL to the new PEL—which are. Industry Br. at 76–77.
    But OSHA specifically addressed Industry’s objection and
    supported its decision to rely on this assumption with
    substantial evidence. 81 Fed. Reg. at 16,473–74. OSHA
    cited data in the record showing that the average worker
    exposed above the prior PEL was exposed at levels
    significantly higher than the prior PEL. Such high exposures
    can be addressed only with certain substantial controls, like
    local exhaust ventilation systems, which in turn account for the
    38
    bulk of the costs associated with exposure reduction. Id.
    Accordingly, OSHA reasoned, since the bulk of the expense
    will come from reducing uncontrolled environments to the
    prior PEL, less cost will result from controls implemented to
    reach the new PEL. Id. Moreover, the reduction from the
    average uncontrolled level (300 µg/m3) to the old PEL (100
    µg/m3) represents a larger reduction—both relatively and
    absolutely—than the reduction from the old PEL (100 µg/m3)
    to the new PEL (50 µg/m3), which mitigates Industry’s claim
    that costs increase disproportionately as facilities reach lower
    exposure levels. OSHA’s assumption here was just that, an
    assumption, which the agency adequately supported on the
    basis of the best available evidence. And given that OSHA’s
    cost estimates were well below its threshold for concern, any
    error resulting from this assumption would be harmless.
    National Cottonseed Products Association v. Brock, 
    825 F.2d 482
    , 488 (D.C. Cir. 1987) (finding OSHA’s failure to include
    certain costs in an economic feasibility analysis to be harmless
    error).
    Industry next faults OSHA for engaging in a per-worker
    assessment of costs—calculating compliance cost based on the
    number of exposed workers—rather than looking at costs on a
    per-facility basis. Industry Br. at 73–76. OSHA, however,
    adequately defended its choice on a perfectly reasonable basis.
    See 81 Fed. Reg. at 16,469–70. OSHA rejected the URS
    study’s facility-based approach because it failed to take into
    account situations where only some but not all workers are
    exposed and where there are existing controls in place;
    according to OSHA, record evidence showed that where one or
    both of these conditions exists, firms can reduce exposure by
    means other than a full set of controls. Id. Though OSHA’s
    approach may understate costs in some situations where fixed
    investment is out of proportion to the number of workers
    impacted, the per-facility approach is vulnerable to the same
    39
    problem in the opposite direction. Between these imperfect
    options, OSHA supported its decision to rely on the per-worker
    approach with substantial evidence—all our standard of review
    requires.
    Industry also criticizes OSHA’s exclusion of the cost of
    certain controls mentioned in its technological feasibility
    analysis. Industry Br. at 77–80. But given that the new rule
    mandates no particular set of controls, OSHA considered the
    lowest-cost combination of controls that would allow the
    typical foundry to meet the new PEL. 81 Fed. Reg. at 16,482.
    This court, moreover, has endorsed this “typical employer”
    approach to economic feasibility. Lead II, 
    939 F.2d at 1005
    .
    OSHA directly addressed Industry’s objection in the preamble
    to the rule: “Just because a control is mentioned in the
    technological feasibility analysis does not mean that OSHA has
    determined that its use is required—only that it represents a
    technologically feasible method for controlling exposures.”
    81 Fed. Reg. at 16,482. Notwithstanding its decision to
    exclude certain controls from its cost analysis, OSHA has
    discharged its duty to provide “a reasonable assessment of the
    likely range of costs of [the] standard.” Lead II, 
    939 F.2d at 1006
     (alteration in original) (emphasis added) (quoting Lead I,
    647 F.2d at 1266).
    Finally, Industry argues that OSHA’s cost estimates do not
    reflect the best available evidence. They contend that the best
    available evidence is “the actual experience of employers that
    have installed the control” as provided by the American
    Foundry Society. Industry Br. at 81 (emphasis omitted).
    They point to two examples—ventilation and housekeeping
    vacuum systems—where the Society’s cost estimates were
    significantly higher than OSHA’s. Id. at 80–83. OSHA,
    however, adequately defended its cost estimates for both of
    these controls. For ventilation systems, OSHA based its cost
    40
    estimate on analysis by its contractor, Eastern Research Group,
    finding the estimates to be reasonable, while acknowledging
    “that there can be a wide range of both capital and operating
    costs associated with” ventilation. 81 Fed. Reg. at 16,480.
    For housekeeping, OSHA based its estimate on its calculation
    of average production floor space from NIOSH field studies
    and cost evidence from a firm specializing in the industrial
    cleaning of foundries. Id. at 16,481. OSHA considered and
    rejected Industry’s higher estimates of housekeeping costs,
    which were based on a single quote and “communicat[ions]
    with industry representatives.” Id. at 16,481–82. OSHA’s
    well-supported estimates and considered rejection of
    alternative evidence are sufficient to justify its findings of
    economic feasibility.
    2. Hydraulic Fracturing
    Industry alleges that OSHA relied upon “industry revenues
    and profits, which . . . do not reflect the real world” because
    they fail to capture a “significant drop in revenue” resulting
    from declining oil prices. Industry Br. at 84. In its final
    analysis, OSHA incorporated the most recent data available
    and performed additional analysis to ensure that the new rule
    would not imperil the hydraulic fracturing industry. 81 Fed.
    Reg. at 16,549. OSHA expressly acknowledged that the
    “recent drop in oil prices has caused a series of bankruptcies
    and closures across the oil industry,” but cited a forecast of
    increased oil prices in the coming years. Id. at 16,549–50.
    Recognizing the uncertainty inherent in such predictions,
    OSHA observed that the cost of complying with the rule is a
    “small fraction” of the cost to the industry of fluctuation in
    energy prices. Id. at 16,550. And OSHA’s delayed
    implementation timeline in hydraulic fracturing gives the
    industry further opportunity to develop new, cost-efficient
    technologies. See Lead I, 647 F.2d at 1265 (“Granting
    41
    companies reasonable time to comply with new PELs might
    . . . enhance economic feasibility generally . . . .”).
    OSHA concluded that “even in a lower price environment,
    hydraulic fracturing entrepreneurs will be able to implement
    the controls required by th[e] final rule without imposing
    significant costs, causing massive economic dislocations to the
    . . . industry, or imperiling the industry’s existence.” 81 Fed.
    Reg. at 16,550. Given the inherent uncertainty in forecasting
    future economic conditions, OSHA’s thorough consideration
    of Industry’s concerns, and the delayed implementation
    timeline, OSHA’s finding that the rule is economically feasible
    in hydraulic fracturing finds ample support in the record.
    Though Industry’s arguments raise concerns about the
    fundamental health of the hydraulic fracturing industry, they
    never claim that OSHA’s rule will seal the industry’s fate.
    As a final matter, Industry again argues that OSHA
    underestimated compliance costs by including the cost of only
    some of the controls discussed in the technological feasibility
    analysis. Industry Br. at 83–85. But this argument fails here
    just as it did for foundries: OSHA estimated only the typical
    cost of compliance and need not consider every single control
    discussed. See Lead II, 
    939 F.2d at 1005
    .
    3. Construction
    Industry first contends that OSHA’s final cost estimates
    “make no sense in the real world of construction,” pointing to
    several industry subgroups where OSHA’s estimated
    annualized cost per affected establishment is under $1,000.
    Industry Br. at 106. But just because the amounts seem low
    does not imply that they are unsupported. And OSHA
    explained that many firms have only a handful of affected
    employees, 81 Fed. Reg. at 16,408, and that recommended
    controls are often inexpensive systems integrated into hand
    42
    tools, id. at 16,436. In light of OSHA’s explanation of the
    reason for the apparently low costs in certain construction
    industry groups, Industry’s bare argument that the costs are too
    low carries little weight.
    Next, Industry critiques OSHA’s assumption of a 150-day
    working year, which Industry argues is too short and thus
    understates costs. Industry Br. at 107–08. But OSHA points
    to sufficient record evidence supporting this assumption:
    equipment cannot be used with perfect efficiency, especially in
    light of weather conditions that interfere with construction.
    Although OSHA does not explain how it arrived at 150 days,
    any error would be harmless. 81 Fed. Reg. at 16,494.
    Moreover, OSHA explains that this assumption does not
    function the way Industry describes: the agency used the 150-
    day assumption only as a divisor when calculating the per-day
    cost of certain engineering controls. As a result, increasing
    the days-per-year assumption would actually decrease the cost
    per day. OSHA Br. at 141–42. Even were this assumption to
    function in the way Industry imagines, costs in construction
    would have had to triple before triggering OSHA’s threshold
    for further inquiry, confirming that OSHA’s ultimate
    conclusion was well supported. 81 Fed. Reg. at 16,573.
    Finally, Industry objects to OSHA’s calculation of
    compliance costs based on an assumption that employers will
    follow Table 1, arguing that this “ignores substantial evidence
    in the record that employers will not be able to follow Table 1
    in all of the operations all of the time.” Industry Br. at 108–
    10. As before, however, OSHA need not look at the cost of
    compliance for all employers in all operations all of the time;
    rather, it is required to consider only the typical compliance
    costs for the “typical” employer. Lead II, 
    939 F.2d at 1005
    .
    OSHA did just that; indeed, the agency did more, calculating
    alternative compliance costs for operations categorically
    43
    excluded from Table 1 (tunnel boring, for example), 81 Fed.
    Reg. at 16,486, and estimating sampling and monitoring costs
    for employers whose exposure levels are so low as to never
    trigger the rule’s requirements and who would thus not follow
    Table 1, id. at 16,514.
    Conclusion
    OSHA’s cost estimates in each of these industries are
    inevitably imperfect due to the limitations of available data and
    the uncertainties inherent in predicting future costs. But this
    is why “hard and precise estimates of costs” are not required.
    Lead II, 
    939 F.2d at 1006
     (quoting Lead I, 647 F.2d at 1266).
    OSHA’s only obligation is to confirm, on the basis of
    substantial evidence, that its rule does not “threaten massive
    dislocation to, or imperil the existence of, the industry.” Id. at
    980 (quoting Lead I, 647 F.2d at 1265). There can be little
    doubt that OSHA has done so here.
    D. PROCEDURAL CHALLENGES
    Both the OSH Act and the APA, which govern the process
    for promulgating occupational safety and health standards,
    require the Secretary to publish proposed rules and provide an
    opportunity for comment. 
    29 U.S.C. § 655
    (b)(2); 
    5 U.S.C. § 553
    . “[I]n order to allow for useful criticism, it is especially
    important for the agency to identify and make available
    technical studies and data that it has employed in reaching the
    decisions to propose particular rules.” American Radio Relay
    League, Inc. v. FCC, 
    524 F.3d 227
    , 236 (D.C. Cir. 2008)
    (quoting Connecticut Light & Power Co. v. Nuclear Regulatory
    Commission, 
    673 F.2d 525
    , 530 (D.C. Cir. 1982)). “An
    agency commits serious procedural error when it fails to reveal
    portions of the technical basis for a proposed rule in time to
    allow for meaningful commentary.”              Owner-Operator
    Independent Drivers Association v. Federal Motor Carrier
    44
    Safety Administration, 
    494 F.3d 188
    , 199 (D.C. Cir. 2007)
    (quoting Solite Corp. v. EPA, 
    952 F.2d 473
    , 484 (D.C. Cir.
    1991) (per curiam)).
    Industry points to two alleged procedural defects in
    OSHA’s process.
    First, Industry faults OSHA for disclosing data from the
    OSHA Information System (OIS) on the last day of the data-
    submission period—June 3, 2014—thereby depriving Industry
    of an opportunity to respond. Industry Br. at 117–18. But
    OSHA’s reliance on the OIS data was unproblematic given that
    it provided adequate opportunity for comment. After the data-
    submission period, OSHA offered an additional two months—
    until August 18—for parties to submit final briefs and
    arguments, a deadline that OSHA twice extended. 81 Fed.
    Reg. at 16,298. Though Industry argues that they had no
    opportunity to submit additional data in response to the OIS
    data, they never explain why the two-month response period
    was insufficient to allow them opportunity for “meaningful
    commentary.”         Owner-Operator Independent Drivers
    Association, 
    494 F.3d at 199
    . Nor does Industry make any
    effort to explain why they were prejudiced by OSHA’s actions.
    Barring a total failure to engage in notice and comment, we
    “will not set aside a rule absent a showing by the petitioners
    ‘that they suffered prejudice from the agency’s failure to
    provide an opportunity for public comment.’” American
    Radio Relay League, 
    524 F.3d at 237
     (quoting Gerber v.
    Norton, 
    294 F.3d 173
    , 182 (D.C. Cir. 2002)). OSHA’s actions
    here were at worst harmless, and, more likely, not even in error.
    Second, Industry criticizes OSHA’s reliance on data and
    estimates from its contractor Eastern Research Group (ERG),
    arguing that OSHA failed to disclose the basis for ERG’s
    assumptions. Industry Br. at 119–21. This court has
    45
    previously approved OSHA’s reliance on information from
    external consultants in rulemaking, making clear that the key
    question is whether the challenger can “buttress its general
    allegation of excessive reliance with any specific proof that the
    [agency] failed to confront personally the essential evidence
    and arguments in setting the final standard.” See Lead I, 647
    F.2d at 1217. Here, OSHA placed all available ERG evidence
    in the record and made clear what information it relied upon in
    reaching its conclusions. Though Industry criticizes OSHA
    for relying on ERG’s “estimates” and interviews with
    unidentified individuals, they fail to propose alternative data
    sources or explain why ERG’s opinions are insufficient.
    Industry has given us no grounds for questioning OSHA’s
    conclusion that ERG provided the best available evidence.
    E. ANCILLARY CHALLENGES
    Although reducing the PEL to 50 µg/m3 represents the
    Rule’s central innovation, OSHA determined that even the
    reduced PEL poses substantial employee health risks. See 81
    Fed. Reg. at 16,287 (“[OSHA] considers the level of risk
    remaining at the new PEL to be significant.”). The Rule
    therefore contains ancillary measures designed to “provid[e]
    additional layers and types of protection” to exposed
    employees. Id. at 16,294. Industry challenges two of these
    measures. Finding that substantial evidence supports OSHA’s
    choices, we reject both challenges. See International Union,
    United Automobile, Aerospace & Agricultural Implement
    Workers of America, UAW v. Pendergrass (Formaldehyde),
    
    878 F.2d 389
    , 391–92 (D.C. Cir. 1989) (reviewing ancillary
    provisions under substantial evidence standard).
    1. Medical Surveillance
    Industry first targets the Rule’s medical surveillance
    provisions. Under the Rule, employers must offer no-cost
    46
    medical surveillance to certain silica-exposed employees. See
    
    29 C.F.R. §§ 1910.1053
    (i)(1)(i);      1926.1153(h)(1)(i).
    Participating employees receive periodic medical screening
    and written reports that include, among other things, the
    examining      physician’s      recommendations        regarding
    “limitations on the employee’s exposure to respirable
    crystalline    silica.”          
    Id.
         §§ 1910.1053(i)(5)(iii);
    1926.1153(h)(5)(iii). But absent the employee’s written
    authorization,    the    employer       never    receives    the
    recommendations.                Id.       §§ 1910.1053(i)(6)(ii);
    1926.1153(h)(6)(ii).
    Industry challenges OSHA’s decision to let employees
    decide whether to notify their employers of their doctors’
    recommendations. Past standards, Industry argues, entitled
    employers to such information regardless of employee consent.
    And, Industry further contends, the Rule’s novel consent-based
    approach unreasonably risks withholding from employers
    information needed to ensure workplace safety.
    Industry correctly observes that prior OSHA standards
    have unconditionally entitled employers to notice of their
    employees’ medically indicated exposure limitations. See,
    e.g.,      id.      §§ 1910.1026(k)(5)(i)(B)      (chromium);
    1910.1028(i)(7)(i)(C)     (benzene);    1926.62(j)(3)(v)(A)(2)
    (lead). Agencies, however, are “free to change their existing
    policies as long as they provide a reasoned explanation for the
    change.” Encino Motorcars, LLC v. Navarro, 
    136 S. Ct. 2117
    ,
    2125 (2016). Agencies undertaking such a change “need not
    always provide a more detailed justification than what would
    suffice for a new policy created on a blank slate,” so long as
    they “display awareness that [they are] changing position” and
    “show that there are good reasons for the new policy.” 
    Id.
     at
    2125–26 (quoting FCC v. Fox Television Stations, Inc., 
    556 U.S. 502
    , 515 (2009)); see also Formaldehyde, 
    878 F.2d at
    400
    47
    (requiring “at the least some explanation” for an agency’s
    “‘swerve’ from prior practice”).
    In the Rule’s preamble, OSHA openly acknowledged that
    the Rule’s consent-based approach to reporting employees’
    medical restrictions treads new ground. See 81 Fed. Reg. at
    16,834 (“The requirements for the type of information
    provided to the employer [under the Rule’s medical
    surveillance provisions] are different from requirements of
    other OSHA standards . . . .”). OSHA has also offered good
    reasons for its new approach, explaining that disregarding
    employees’ “reluctance to let employers know about their
    health status” could compromise worker safety by deterring
    employees fearful of the employment consequences of an
    adverse diagnosis from participating in medical surveillance.
    Id. at 16,832. And, more generally, “evolving notions about
    where the balance between preventive health policy and patient
    privacy is properly struck,” id. at 16,831, led OSHA to
    conclude that “employees have the most at stake in terms of
    their health and employability” and so should be entitled to
    decide for themselves whether to relay potentially
    compromising medical information, id. at 16,833.
    Industry challenges OSHA’s decision to allow employees
    to withhold medical information from their employers, arguing
    that knowing employees’ health status helps employers adopt
    appropriate workplace health and safety measures. OSHA
    considered and reasonably rejected this argument during the
    rulemaking.     Silica-related illnesses have long latency
    periods, and OSHA reasoned that an employee’s present
    diagnosis with an illness likely contracted long ago “will not
    provide useful information about” the efficacy of an
    employer’s “current controls or exposure conditions.” Id.
    (emphasis added). And although knowing which silica-
    exposed employees are particularly vulnerable to adverse
    48
    health effects could prompt an employer to find safer
    placements for those employees, OSHA preferred to leave
    employees the freedom to decide for themselves whether to
    seek such a placement. Because OSHA has “explain[ed] its
    logic and the policies underlying its choices,” we have no basis
    for second-guessing its reasonable judgments. National
    Maritime Safety Association, 
    649 F.3d at 752
    .
    Industry also argues that the Rule’s medical surveillance
    provisions exceed OSHA’s statutory authority to regulate.
    Absent unconditional employer notification, Industry argues,
    medical surveillance lacks the workplace nexus that is
    prerequisite to OSH Act regulation. See Cotton Dust, 
    452 U.S. at 540
     (“[T]he [OSH] Act in no way authorizes OSHA to
    repair general unfairness to employees that is unrelated to
    achievement of health and safety goals . . . .”). But the Rule’s
    medical surveillance provisions obviously possess such a
    nexus. After all, an employer assumes medical surveillance
    obligations only by exposing its employees to workplace silica,
    thereby creating the need to assess the exposure’s potential
    health effects. Although Industry fleetingly argues that the
    medical surveillance provisions violate the OSH Act’s
    disclaimer of authority to “supersede or in any manner affect”
    state worker’s compensation systems, 
    29 U.S.C. § 653
    (b)(4), it
    entirely fails to explain how.
    2. Dry Sweeping, Dry Brushing, and Compressed Air
    Industry’s second challenge to the Rule’s ancillary
    provisions targets measures that prohibit dry sweeping, dry
    brushing, or (barring suitable ventilation) the use of
    compressed air for certain purposes “where such activity could
    contribute to employee [silica] exposure” and if alternative
    methods are feasible. See 
    29 C.F.R. §§ 1910.1053
    (h);
    1926.1153(f). The proposed rule would have limited these
    49
    housekeeping methods only where they could “contribute to
    employee exposure to respirable crystalline silica that exceeds
    the PEL.” 78 Fed. Reg. at 56,274, 56,499 (Sept. 12, 2013)
    (emphasis added). The final rule, though, instead restricts
    these methods whenever they could contribute to silica
    exposure to any degree. Industry argues that this revision is
    unsupported by substantial evidence because it essentially
    imposes a wholesale prohibition on the covered methods.
    Industry’s challenge fails. OSHA found that silica
    exposure, even at levels below the PEL, poses significant risks
    to employee health, see 81 Fed. Reg. at 16,796, and that the
    Rule’s restrictions on dry sweeping, dry brushing, and the use
    of compressed air reduce exposure, see id. at 16,794. Except
    insofar as Industry argues that OSHA lacked substantial
    evidence to find significant employee health risks even at the
    PEL—an argument that we have already rejected, see supra
    Part II.A—Industry presents no meaningful challenge to these
    findings. Industry briefly suggests that a study cited in the
    Rule’s preamble as linking dry sweeping to increased silica
    exposure was “insufficient to support OSHA’s prohibition on
    all dry sweeping, dry brushing, or use of compressed air that
    contributes to employee exposure to silica at any level.”
    Industry Reply Br. at 63. The study, however, cited as an
    “example,” was not the sole basis for OSHA’s conclusions.
    See 81 Fed. Reg. at 16,794 (summarizing comments that
    discuss other studies).
    Having failed to undermine OSHA’s supportable finding
    that the Rule’s housekeeping provisions promote worker
    safety, Industry next argues that OSHA inadequately addressed
    concerns that alternatives to the restricted housekeeping
    methods can be hazardous or impractical. But OSHA
    explained in the preamble that the Rule resolves precisely these
    concerns by allowing employers to use the restricted methods
    50
    where alternatives are infeasible. See id. at 16,796 (“[I]n
    situations where [alternatives] would not be effective, would
    cause damage, or would create a hazard in the workplace, the
    employer is not required to use these [alternative] cleaning
    methods.”). Industry quibbles that “[t]he Rule does not define
    what is feasible in any particular situation” and that the
    employer bears the burden of showing an alternative’s
    infeasibility, Industry Br. at 115–16, though it offers nothing
    beyond unsupported speculation to suggest that the
    infeasibility exception will inadequately serve the very purpose
    for which it was adopted.
    F. UNION CHALLENGES
    We turn finally to the Unions’ challenges.
    As it has with many long-latency occupational diseases,
    OSHA required employers to provide medical exams to help
    combat the risks posed by silicosis and other silica-related
    diseases. 
    29 C.F.R. §§ 1910.1053
    (i); 1926.1153(h). OSHA
    concluded that such exams “will allow for identification of
    respirable crystalline silica-related adverse health effects at an
    early stage so that appropriate intervention measures can be
    taken.” 81 Fed. Reg. at 16,625. Employer-provided medical
    surveillance not only motivates employers to reduce exposures
    to avoid surveillance costs, but also provides information to
    employees so that they can “take action, such as changing jobs
    or wearing a respirator for additional protection.” Id. at
    16,626.
    The Unions’ challenges are to the temporal bookends to
    these medical exams. The construction unions challenge (in
    the construction standard only) the initial trigger for when an
    employer must offer an exam. The general industry unions
    challenge (in the general industry standard only) what happens
    after an exam is completed.
    51
    1. Medical Surveillance Trigger
    In the general industry standard, employers must offer
    triennial exams to any employee “who will be occupationally
    exposed . . . at or above the action level for 30 or more days per
    year.” 
    29 C.F.R. §§ 1910.1053
    (i)(1)(i); 1910.1053(i)(3).
    OSHA used the action level of 25 µg/m3 for this trigger because
    it concluded that a significant risk persisted at the PEL of
    50 µg/m3, and that employees exposed at lower levels still
    faced a significant risk of developing silica-related diseases.
    In the construction standard, however, OSHA determined that
    it would be impractical for medical surveillance to be triggered
    by any particular exposure limit because OSHA anticipated
    that most construction employers would rely on Table 1 and
    would not make exposure assessments. 81 Fed. Reg. at
    16,815; see generally supra Part II.B.3. OSHA therefore
    required construction employers to provide surveillance to
    employees “who will be required . . . to use a respirator for 30
    or more days per year” with that employer. 
    29 C.F.R. § 1926.1153
    (h)(1)(i); see 81 Fed. Reg. at 16,817. Because
    respirator use in the construction industry (in Table 1) is
    generally tied to exposure at or above the PEL of 50 µg/m3,
    construction employees may be exposed to greater silica
    concentrations before receiving medical surveillance than
    general industry employees, for whom surveillance is tied to
    exposure at the action level of 25 µg/m3.
    The Unions do not dispute that keying medical exams to
    respirator use is sensible because using Table 1 eliminates the
    need to measure actual exposure. Union Br. at 36; Union
    Reply Br. at 14. The Unions are concerned, however, that
    some employees might use a respirator for 30 days in a year—
    and therefore endure exposures at or above the PEL for 30
    days—but fall through the cracks of OSHA’s screening
    mechanism because they split that use across multiple
    52
    employers. 8      This problem is especially acute in the
    construction industry, the Unions argue, because
    “[e]mployment in the construction industry is transitory and
    intermittent.” Union Br. at 36. The solution to the problem,
    they suggest, is for even a single day of respirator use to trigger
    medical screening. 9
    In Asbestos, a union challenged OSHA’s decision to
    trigger some employer duties at the action level and others at
    the PEL. The union argued that it was “feasible to trigger
    many of the latter duties at the action level rather than at the
    PEL, and that the Secretary therefore erred in not so
    providing.” 
    838 F.2d at 1274
    . OSHA had defended its
    decision as reasonable priority-setting that “permit[ted]
    employers to concentrate their resources on those employees
    and workplace conditions with the potential for high asbestos
    exposures.” 
    Id.
     (quoting Occupational Exposure to Asbestos,
    
    51 Fed. Reg. 22,612
    , 22,707 (June 20, 1986)). This court, like
    the union, was “skeptical of the agency’s asserted justification”
    because it did not explicitly relate to either feasibility or lack
    of benefit. 
    Id.
    Nonetheless, the court rejected the union’s challenge. As
    we explained, “the force of the evidence and argument that
    OSHA must offer to defend its choice will vary with the force
    of the proponent’s evidence and argument.” 
    Id. at 1271
    . And
    8
    The Unions also express concern that an employer might be
    unable to predict an employee’s respirator use in the coming year.
    Union Br. at 38. As OSHA explained in the preamble, however, the
    trigger is met as soon as the employer knows respirator use will
    exceed 30 days in the year, even if the employer did not initially
    anticipate such use. 81 Fed. Reg. at 16,818.
    9
    Counsel conceded at oral argument that the Unions did not
    advance before the agency the alternative approach of tracking
    employees’ respirator use across employers. Oral Arg. at 1:57:25.
    53
    the burden is on the challenger to a rule to “demonstrat[e] that
    the variations it advocates will be feasible to implement and
    will provide more than a de minimis benefit for worker health.”
    Id. Because in that case the union “failed to point to any
    evidence” that using the stricter trigger “would result in a
    greater than de minimis incremental benefit,” we concluded
    that OSHA had not abused its discretion in rejecting the
    suggested provision. Id. at 1274.
    Following this approach today, we reject the Unions’
    challenge to the medical surveillance trigger in the construction
    standard. OSHA’s stated reason for adopting the 30-day
    trigger does leave something to be desired. OSHA noted that
    commenters had suggested a range of possible triggers, and it
    selected 30 days as “strik[ing] a reasonable balance between
    the administrative burden of offering medical surveillance to
    all employees, many of whom may not be further exposed or
    only occasionally exposed, and the need for medical
    surveillance for employees who are regularly exposed and
    more likely to experience adverse health effects.” 81 Fed.
    Reg. at 16,816. The Unions suggest that this statement
    reflects the kind of balancing of “burdens and benefits” that is
    impermissible for rulemaking under 
    29 U.S.C. § 655
    (b)(5).
    Union Br. at 39; see Cotton Dust, 
    452 U.S. at 509
    ; National
    Cottonseed Products Association, 
    825 F.2d at
    485 n.1.
    We do not, however, construe such a “casual” comment
    “as amounting to an arguably improper cost-benefit test,
    especially when OSHA has expressed its vigorous opposition
    to such a test.” Lead I, 647 F.2d at 1309. OSHA did not
    explicitly frame its rejection of the Unions’ proposal as
    infeasible or as failing to protect against a material impairment
    of health, the relevant considerations under § 655(b)(5). But
    “[a]s long as the agency’s path may reasonably be discerned,
    we will uphold the decision even if it is of less than ideal
    54
    clarity.” Casino Airlines, Inc. v. National Transportation
    Safety Board, 
    439 F.3d 715
    , 717 (D.C. Cir. 2006) (internal
    quotation marks omitted). OSHA’s explanation that many
    employees would not be further exposed or only occasionally
    exposed indicates that the agency saw little benefit in providing
    medical surveillance to workers exposed at or above the PEL
    for fewer than 30 days a year. And as in Asbestos, the Unions
    have not pointed to any evidence that setting the trigger at one
    day instead of 30 days would produce more than a de minimis
    benefit to worker health. Indeed, they have not identified how
    many—if any—employees would use a respirator more than 30
    days in a year, but would not do so with any single employer.
    Nor did OSHA act unreasonably in rejecting the Unions’
    speculation that construction employers might deliberately
    terminate employees nearing the 30-day trigger in an effort to
    avoid the costs of medical surveillance, given that the costs of
    hiring and training a new employee would likely exceed the
    “modest” cost of providing triennial medical examinations for
    an existing employee. 81 Fed. Reg. at 16,817. That being so,
    we conclude that OSHA did not abuse the “almost unlimited
    discretion the statute affords it to devise means to achieve the
    congressionally mandated goal.” Asbestos, 
    838 F.2d at 1271
    (internal quotation marks omitted).
    2. Medical Removal Protection
    Medical removal protection (MRP) provisions “typically
    require the employer to temporarily remove an employee from
    exposure when such an action is recommended in a written
    medical opinion” and to “maintain the employee’s total normal
    earnings, as well as all other employee rights and benefits,”
    during the removal.        81 Fed. Reg. at 16,838; see
    Formaldehyde, 
    878 F.2d at 399
    . 10 OSHA has included MRP
    10
    In this opinion, we use MRP to refer to transfer and wage
    protections generally, and not to refer to any specific scheme.
    55
    provisions in some of its rules addressing worker health.
    Indeed, it recently did so in the beryllium standard, 
    82 Fed. Reg. 2,470
    , 2,720–21 (Jan. 9, 2017), which it promulgated after
    the Silica Rule that is now before us. This court approved
    such a provision in the lead standard, accepting OSHA’s
    explanation that “removal was a preventive device” and that,
    “unless workers were guaranteed all their wage and seniority
    rights upon removal, they would resist cooperating with the
    medical surveillance program that determined the need for
    removal, since they reasonably might fear being fired or sent to
    lower-paying jobs if they revealed dangerously high blood-lead
    levels.” Lead I, 647 F.2d at 1237.
    OSHA has not always included MRP in its health
    standards, however. See, e.g., Hexavalent Chromium Rule,
    
    71 Fed. Reg. 10,100
    , 10,366 (Feb. 28, 2006); Ethylene Oxide
    Rule, 
    49 Fed. Reg. 25,734
    , 25,788 (June 22, 1984). And when
    it promulgated the Silica Rule, the agency had previously
    included MRP in only six standards. See 81 Fed. Reg. at
    16,838. It did not include MRP in the Rule’s general industry
    standard, a decision the Unions now challenge.
    To start, we reject OSHA’s suggestion that we should deny
    the Unions’ petition because they did not present sufficient
    evidence of MRP’s economic feasibility. We can uphold a
    rule only on grounds upon which the agency itself relied. See
    NLRB v. CNN, 
    865 F.3d 740
    , 751 (D.C. Cir. 2017). And the
    agency did not purport to reject MRP on that ground in the
    silica rulemaking. See 81 Fed. Reg. at 16,838–40.
    According to the Unions, OSHA engaged in unreasoned
    decisionmaking in failing to provide MRP for those employees:
    (a) whose doctors recommend permanent removal; (b) whose
    doctors recommend temporary removal to alleviate
    exacerbated symptoms of chronic obstructive pulmonary
    56
    disease (COPD); (c) whose doctors recommend temporary
    removal pending a determination by a specialist; and (d) who
    are unable to wear a required respirator. The Unions contend
    that OSHA’s stated reasons for rejecting MRP in each of these
    four circumstances are inadequate.
    (a). We begin with OSHA’s rationale for denying any
    period of MRP to employees whose doctors recommend
    permanent removal.         OSHA acknowledged that “some
    employees might benefit from removal from respirable
    crystalline silica exposure to possibly prevent further
    progression of disease.” 81 Fed. Reg. at 16,839; see Oral Arg.
    at 2:07:07–:15.       But temporary removal would rarely
    “improve employee health,” OSHA said, because silica-related
    illnesses are irreversible. 81 Fed. Reg. at 16,839. To produce
    a lasting health benefit, “removal[] would have to be
    permanent,” and “[w]orkers’ compensation is the appropriate
    remedy when permanent removal from exposure is required.”
    Id.
    In some previous rules, however, OSHA has provided
    MRP for employees whose doctors recommend permanent
    removal. See, e.g., 29 C.F.R § 1910.1028(i)(8)(v) (benzene).
    And we have held that the agency cannot rely “on an across-
    the-board rule that appears inconsistent with past decisions.”
    Formaldehyde, 
    878 F.2d at 401
     (opinion on rehearing). One
    reason OSHA has provided MRP is to ensure that employees
    fully engage with medical surveillance by reporting their
    symptoms.       Absent MRP, employees might conceal
    symptoms rather than risk “being fired or sent to lower-paying
    jobs if they revealed” those symptoms. Lead I, 647 F.2d at
    1237; see Formaldehyde, 
    878 F.2d at 400
    . In the Silica Rule,
    however, OSHA dismissed this rationale. Even without MRP,
    it said, employees would readily cooperate with examining
    physicians because the Rule’s enhanced medical privacy
    57
    protections would eliminate the risk of automatic wage loss.
    81 Fed. Reg. at 16,389–40. Those protections withhold
    doctors’ recommendations from employers absent employees’
    written authorizations. See supra Part II.E.1.
    OSHA’s explanation misses a logical step. According to
    OSHA, medical surveillance provides information so that
    employees can “take action, such as changing jobs or wearing
    a respirator for additional protection.” 81 Fed. Reg. at 16,626.
    The medical privacy protections may well mitigate the concern
    that employees will underreport symptoms to their doctors.
    But without MRP, employees whose doctors recommend
    removal may hide those recommendations from their
    employers.
    OSHA has acknowledged that continued exposure can
    worsen even an irreversible silica-related disease. See id. at
    16,839; see Oral Arg. at 2:07:07–:15. And OSHA has not
    explained why MRP—critical in some standards to protect
    workers from having to decide between learning about their
    health and avoiding economic loss—is not equally critical to
    protect workers from having to choose between disclosing their
    health issues (and thus preserving their health) and avoiding
    economic loss. Because OSHA acknowledges the health
    benefit of removal and has not given an adequate reason for
    rejecting some period of MRP for employees whose doctors
    recommend permanent removal, we remand to the agency for
    reconsideration or further explanation.
    (b).    OSHA also concedes that, in some cases,
    “employees might benefit from temporary removal . . . to
    alleviate exacerbation of COPD.” 81 Fed. Reg. at 16,839; see
    Oral Arg. at 2:09:41–:10:20. OSHA nonetheless rejected
    medically recommended temporary removal because
    symptoms likely would recur at some point after the removal
    58
    ended. But OSHA’s statutory mandate directs it to “set the
    standard which most adequately assures . . . that no employee
    will suffer material impairment of health . . . .” 
    29 U.S.C. § 655
    (b)(5). And, as OSHA explained in the preamble to this
    rule, the agency considers “irritation of the skin, eyes, and
    respiratory system . . . to be material impairments of health.”
    81 Fed. Reg. at 16,290. OSHA may have valid reasons for
    rejecting MRP for temporary removal to alleviate exacerbated
    symptoms, but the fact that symptoms might recur when the
    removal ends is not by itself a sufficient reason. Thus, a
    remand to further address this circumstance is also warranted.
    (c). OSHA also rejected the Unions’ proposal that it
    require MRP for those employees whose doctors recommend
    temporary removal pending a determination by a specialist.
    Although OSHA’s brief recognizes that the agency has
    required such temporary removal under other standards, it
    argues that removal would not benefit employees in this
    rulemaking because “the available evidence suggests that,
    given the slow progression of silica-related diseases, ‘there is
    no urgent need for removal from . . . exposure while awaiting
    a specialist determination.’” OSHA Br. at 157 (quoting 81
    Fed. Reg. at 16,840).
    But that is not quite what OSHA said in the rulemaking.
    Rather, it said that “in most cases, there is no urgent need for
    removal from [silica] exposure while awaiting a specialist
    determination.” 81 Fed. Reg. at 16,840 (emphasis added).
    And it acknowledged that, although rare, one type of
    silicosis—“acute silicosis”—is an exception to the generality
    that silica-related diseases progress slowly. Id. Indeed,
    OSHA said that “acute silicosis can occur within a few weeks
    to months after inhalation exposure to extremely high levels”
    of silica, leading to death “within months to a few years of
    disease onset.” Id. at 16,381. In light of that, the agency has
    59
    not explained why temporary removal would not benefit those
    workers whose physicians have found enough initial signs of
    the disease to indicate referral to a specialist. We therefore
    remand for the agency to better explain its decision not to
    require MRP in this circumstance as well.
    (d). Although OSHA’s reasons for not requiring MRP in
    the three circumstances just discussed are inadequate to sustain
    those decisions, we reject the Unions’ contention that OSHA
    failed to engage in reasoned decisionmaking by not including
    MRP for employees who are unable to wear a respirator.
    OSHA concluded that such a provision was unnecessary
    because OSHA already requires employers to provide a
    powered air-purifying respirator to employees who are unable
    to wear a negative pressure respirator. 81 Fed. Reg. at 16,840;
    see 
    29 C.F.R. § 1910.134
    (e)(6) (respiratory protection). The
    Unions speculate that some employees might be unable to wear
    either type of respirator, but they have not pointed to any
    evidence indicating how many such employees there are likely
    to be. We therefore reject this challenge because the Unions
    have not met their burden to show that MRP would provide
    more than a de minimis benefit in this circumstance. See
    Asbestos, 
    838 F.2d at 1271
    .
    60
    III. CONCLUSION
    In sum, we reject all of the petitioners’ challenges to the
    Silica Rule, with three exceptions. We hold that OSHA was
    arbitrary and capricious in declining to require MRP for some
    period when a medical professional recommends permanent
    removal, when a medical professional recommends temporary
    removal to alleviate COPD symptoms, and when a medical
    professional recommends temporary removal pending a
    specialist’s determination. We remand to the agency to
    reconsider or further explain those aspects of the Rule.
    So ordered.