Natural Resources Defense Council, Inc. v. U.S. Environmental Protection Agency

Jerome H. Heckman, Peter L. delaCruz, Gary H. Baise, Robert Brager, Brenda Mallory, Albert J. Beveridge III and Don G. Scroggin, Washington, D.C., were on the brief for intervenor, The Vinyl Institute.

Daniel Marcus, Washington, D.C., was on the brief for amicus curiae, American Iron and Steel Institute, urging approval of E.P.A. action to withdraw proposed amendments to the vinyl chloride standard.

Robert V. Percival, Washington, D.C., was on the brief for amicus curiae, Environmental Defense Fund, urging the grant of Natural Resources Defense Council's petition for review.

G. William Frick, Martha A. Beauchamp, Arthur F. Sampson III and John Gibson Mullan, Washington, D.C., were on the brief for amicus curiae, The American Petroleum Institute, urging affirmance of the panel decision. Stark Ritchie and Arnold Block, Washington, D.C., also entered appearances for the American Petroleum Institute.

David F. Zoll and Neil Jay King, Washington, D.C., were on the brief for amicus curiae, Chemical Manufacturers Ass'n, urging approval of E.P.A. action. Fredric P. Andes, Washington, D.C., also entered an appearance for Chemical Manufacturers Ass'n.

Frederick R. Anderson, Washington, D.C., was on the brief for amicus curiae, Various Professors of Law, urging the reversal of the panel decision.

Before WALD, Chief Judge, ROBINSON, MIKVA, EDWARDS, RUTH B. GINSBURG, BORK, STARR, SILBERMAN, BUCKLEY, WILLIAMS and D.H. GINSBURG, Circuit Judges.

Opinion for the Court filed by Circuit Judge BORK.

Current scientific knowledge does not permit a finding that there is a completely safe level of human exposure to carcinogenic agents. The Administrator of the Environmental Protection Agency, however, is charged with regulating hazardous pollutants, including carcinogens, under section 112 of the Clean Air Act by setting emission standards "at the level which in his judgment provides an ample margin of safety to protect the public health." 42 U.S.C. Sec. 7412(b)(1)(B) (1982). We address here the question of the extent of the Administrator's authority under this delegation in setting emission standards for carcinogenic pollutants.

Petitioner Natural Resources Defense Council ("NRDC") contends that the Administrator must base a decision under section 112 exclusively on health-related factors and, therefore, that the uncertainty about the effects of carcinogenic agents requires the Administrator to prohibit all emissions. The Administrator argues that in the face of this uncertainty he is authorized to set standards that require emission reduction to the lowest level attainable by best available control technology whenever that level is below that at which harm to humans has been demonstrated. We find no support for either position in the language or legislative history of the Clean Air Act. We therefore grant the petition for review and remand to the Administrator for reconsideration in light of this opinion.

Section 112 of the Clean Air Act provides for regulation of hazardous air pollutants, which the statute defines as "air pollutant[s] to which no ambient air quality standard is applicable and which in the judgment of the Administrator cause[ ], or contribute[ ] to, air pollution which may reasonably be anticipated to result in an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness." 42 U.S.C. Sec. 7412(a)(1) (1982). The statute requires the Administrator to publish a list containing each hazardous pollutant for which he intends to adopt an emission standard, to publish proposed regulations and a notice of public hearing for each such pollutant, and then, within a specified period, either to promulgate an emission standard or to make a finding that the particular agent is not a hazardous air pollutant. See id. Sec. 7412(b)(1)(B). The statute directs the Administrator to set an emission standard promulgated under section 112 "at the level which in his judgment provides an ample margin of safety to protect the public health." Id.

This case concerns vinyl chloride regulations. Vinyl chloride is a gaseous synthetic chemical used in the manufacture of plastics and is a strong carcinogen. In late 1975, the Administrator issued a notice of proposed rulemaking to establish an emission standard for vinyl chloride. 40 Fed.Reg. 59,532 (1975). In the notice, the EPA asserted that available data linked vinyl chloride to carcinogenic, as well as some noncarcinogenic, disorders and that "[r]easonable extrapolations" from this data suggested "that present ambient levels of vinyl chloride may cause or contribute to ... [such] disorders." Id. at 59,533. The EPA also noted that vinyl chloride is "an apparent non-threshold pollutant," which means that it appears to create a risk to health at all non-zero levels of emission. Scientific uncertainty, due to the unavailability of dose-response data and the twenty-year latency period between initial exposure to vinyl chloride and the occurrence of disease, makes it impossible to establish any definite threshold level below which there are no adverse effects to human health. Id. at 59,533-34. The notice also stated the "EPA's position that for a carcinogen it should be assumed, in the absence of strong evidence to the contrary, that there is no atmospheric concentration that poses absolutely no public health risk." Id. at 59,534.

Because of this assumption, the EPA concluded that it was faced with two alternative interpretations of its duty under section 112. First, the EPA determined that section 112 might require a complete prohibition of emissions of non-threshold pollutants because a "zero emission limitation would be the only emission standard which would offer absolute safety from ambient exposure." 40 Fed.Reg. at 59,534. The EPA found this alternative "neither desirable nor necessary" because "[c]omplete prohibition of all emissions could require closure of an entire industry," a cost the EPA found "extremely high for elimination of a risk to health that is of unknown dimensions." Id.

The EPA stated the second alternative as follows:

An alternative interpretation of section 112 is that it authorizes setting emission standards that require emission reduction to the lowest level achievable by use of the best available control technology in cases involving apparent non-threshold pollutants, where complete emission prohibition would result in widespread industry closure and EPA has determined that the cost of such closure would be grossly disproportionate to the benefits of removing the risk that would remain after imposition of the best available control technology.

Id. The EPA adopted this alternative on the belief that it would "produce the most stringent regulation of hazardous air pollutants short of requiring a complete prohibition in all cases." Id.

On October 21, 1976, the EPA promulgated final emission standards for vinyl chloride which were based solely on the level attainable by the best available control technology. 41 Fed.Reg. 46,560 (1976). The EPA determined that this standard would reduce unregulated emissions by 95 percent. Id. With respect to the effect of the standard on health, the EPA stated that it had assessed the risk to health at ambient levels of exposure by extrapolating from dose-response data at higher levels of exposure and then made the following findings:

EPA found that the rate of initiation of liver angiosarcoma among [the 4.6 million] people living around uncontrolled plants is expected to range from less than one to ten cases of liver angiosarcoma per year of exposure to vinyl chloride.... Vinyl chloride is also estimated to produce an equal number of primary cancers at other sites, for a total of somewhere between less than one and twenty cases of cancer per year of exposure among residents around plants. The number of these effects is expected to be reduced at least in proportion to the reduction in the ambient annual average vinyl chloride concentration, which is expected to be 5 percent of the uncontrolled levels after the standard is implemented.

Id. The EPA did not state whether this risk to health is significant or not. Nor did the EPA explain the relationship between this risk to health and its duty to set an emission standard which will provide an "ample margin of safety."

The Environmental Defense Fund ("EDF") filed suit challenging the standard on the ground that section 112 requires the Administrator to rely exclusively on health and prohibits consideration of cost and technology. The EDF and the EPA settled the suit, however, upon the EPA's agreement to propose new and more stringent standards for vinyl chloride and to establish an ultimate goal of zero emissions.

The EPA satisfied its obligations under the settlement agreement by proposing new regulations on June 2, 1977. While the proposal sought to impose more strict regulation by requiring sources subject to a 10 parts per million ("ppm") limit to reduce emissions to 5 ppm, and by establishing an aspirational goal of zero emissions, the EPA made it clear that it considered its previous regulations valid and reemphasized its view that the inability scientifically to identify a threshold of adverse effects did not require prohibition of all emissions, but rather permitted regulation at the level of best available technology. 42 Fed.Reg. 28,154 (1977). The EPA received comments on the proposal, but took no final action for more than seven years. On January 9, 1985, the EPA withdrew the proposal. Noting that certain aspects of the proposed regulations imposed "unreasonable" costs and that no control technology "has been demonstrated to significantly and consistently reduce emissions to a level below that required by the current standard," 50 Fed.Reg. 1182, 1184 (1985), the EPA concluded that it should abandon the 1977 proposal and propose in its place only minor revisions to the 1976 regulations.

This petition for review followed.

We must address at the outset two procedural challenges to the NRDC's petition for review. First, an industry intervenor, the Vinyl Institute, argues that the petition for review is not timely filed. Second, the EPA argues that the NRDC has failed to exhaust its administrative remedies and that we must, therefore, dismiss the petition for review.

The Vinyl Institute argues that this court does not have jurisdiction because the statute provides that "[a]ny petition for review ... shall be filed within sixty days from the date notice of [the] promulgation, approval, or action appears in the Federal Register, except that if such petition is based solely on grounds arising after such sixtieth day, then any petition for review ... shall be filed within sixty days after such grounds arise." 42 U.S.C. Sec. 7607(b)(1) (1982). According to the intervenor, the NRDC seeks review of the 1976 standards and not of the 1985 withdrawal of the proposed amendments. Because grounds for that challenge arose more than sixty days before the NRDC filed the petition for review, the intervenor claims that the petition is untimely. Under Montana v. Clark, 749 F.2d 740 (D.C.Cir.1984), cert. denied, 474 U.S. 919, 106 S.Ct. 246, 88 L.Ed.2d 255 (1985), "an agency decision not to amend long-standing rules after a notice and comment period is reviewable agency action." Id. at 744. Thus, if the petition for review, filed within sixty days of the withdrawal of the proposed amendments, is a genuine challenge to the withdrawal of the proposed regulations, it was timely filed. If, by contrast, the Vinyl Institute is correct in asserting that this petition is a substantive attack on the 1976 regulations, we must dismiss the suit as untimely filed. See Professional Drivers Council v. Bureau of Motor Carrier Safety, 706 F.2d 1216, 1217-18 n. 2 (D.C.Cir.1983). We believe the former is the more accurate characterization of this lawsuit.

The contention that this case is a "back-door" challenge to the 1976 regulations is refuted by the substance of the petitioner's brief and the relief requested. The petitioner states that "[i]n withdrawing the proposed amendments the EPA violated the law by employing cost-benefit and technological feasibility tests that are prohibited by the Clean Air Act." Brief for NRDC at 3. Indeed, the brief makes explicit that the petitioner is specifically challenging the EPA's reliance on cost and technological feasibility in its withdrawal of the proposed amendments. Id. at 11-13. Additionally, the petitioner does not ask the court to overturn the 1976 standards, but rather asks the court to vacate the EPA's decision to withdraw the amendments. See Brief for NRDC at 36-37. We think it clear, therefore, that the NRDC has challenged the 1985 withdrawal of the proposed amendments. The petition for review is timely.

The EPA argues that the petitioner has failed to exhaust available administrative remedies because it failed to participate in the proceedings below. Congress included in section 307(d) of the Clean Air Act a statutory requirement of exhaustion, which provides that "[o]nly an objection to a rule or procedure which was raised with reasonable specificity during the period for public comment (including any public hearing) may be raised during judicial review." 42 U.S.C. Sec. 7607(d)(7)(B) (1982). This statutory requirement of exhaustion, however, does not apply here. The statute also provides that "[t]he requirements of ... subsection [307(d) of the Act] shall take effect with respect to any rule the proposal of which occurs after ninety days after August 7, 1977." 42 U.S.C. Sec. 7607(d)(11) (1982). The withdrawal of the proposed amendments is the final EPA action on a notice of proposed rulemaking that issued on June 2, 1977. See 42 Fed.Reg. 28,154 (1977). Thus, even if we assume that the action of withdrawing a proposed rule amounts to a "rule" for purposes of section 307(d), the proposal withdrawn here was issued before section 307(d) took effect. Accordingly, we must look to the common law doctrine of exhaustion of remedies. See Safir v. Kreps, 551 F.2d 447, 452 (D.C.Cir.), cert. denied, 434 U.S. 820, 98 S.Ct. 60, 54 L.Ed.2d 76 (1977). The result, however, is the same.

Courts have long required a party seeking review of agency action to exhaust its administrative remedies before seeking judicial review. See, e.g., Myers v. Bethlehem Shipbuilding Corp., 303 U.S. 41, 50-51, 58 S.Ct. 459, 463, 82 L.Ed. 638 (1938). In this case, the administrative remedy was participation in the rulemaking proceedings during the comment period. Indeed, this court generally requires such participation as a prerequisite to a petition for direct review of the resulting regulations. See Environmental Defense Fund v. EPA, 598 F.2d 62, 91 (D.C.Cir.1978).

The NRDC did not participate in the rulemaking proceedings in this case, but argues that we should not dismiss its petition for review because the agency in fact considered the statutory issue raised in the petition. The NRDC is correct. This court has excused the exhaustion requirements for a particular issue when the agency has in fact considered the issue. See Washington Ass'n for Television & Children v. FCC, 712 F.2d 677, 682 n. 10 (D.C.Cir.1983); Etelson v. Office of Personnel Management, 684 F.2d 918, 923 (D.C.Cir.1982); ASARCO, Inc. v. EPA, 578 F.2d 319, 320-21 n. 1 (D.C.Cir.1978); Safir v. Kreps, 551 F.2d at 452. Thus, courts have waived exhaustion if the agency "has had an opportunity to consider the identical issues [presented to the court] ... but which were raised by other parties," see Buckeye Cablevision, Inc., v. United States, 438 F.2d 948, 951 (6th Cir.1971), or if the agency's decision, or a dissenting opinion, indicates that the agency had "the opportunity to consider" "the very argument pressed" by the petitioner on judicial review. Office of Communication of the United Church of Christ v. FCC, 465 F.2d 519, 523 (D.C.Cir.1972).

In this case, the issue of whether the EPA may set a standard under section 112 on the basis of cost and technological feasibility was raised before the agency. First, the 1977 proposed amendments were the product of the settlement of a lawsuit challenging the previous vinyl chloride standards on the ground that the EPA impermissibly considered these factors. The EPA, therefore, had notice of this issue and could, or should have, taken it into account in reaching a final decision on the proposed amendments. Indeed, in its notice of proposed rulemaking, the EPA remarked that "[t]he [1976] vinyl chloride standard has been criticized for allegedly placing unwarranted emphasis on technological rather than health considerations." 42 Fed.Reg. 28,154 (1977). The notice then continued by discussing the "ample margin of safety" language, the potential problem under this standard of shutting down an entire industry that produces a nonthreshold pollutant, and the way the proposed amendments resolved the problem by moving toward zero emissions without banning vinyl chloride. Id. Thus, it is clear that the EPA actually did consider the issue raised by the NRDC in its petition for review.

Moreover, the EDF explicitly raised the issue before the EPA in its comments on the proposed amendments. In this respect, the EDF stated:

The proposed amendments represent a true compromise between what EDF could have pressed for in court and the existing standard. Section 112 of the Clean Air Act requires that emission standards for hazardous air pollutants ... be set "at a level which in the judgment of the Administrator provides an ample margin of safety to protect the public health from such hazardous air pollutants." It clearly requires a health-linked, not a technology-based standard. Yet, inconsistent with the statutory requirement, the original standards were based on what EPA believed industry could accomplish with best available technology.... EPA recognized that vinyl chloride is "an apparent non-threshold pollutant" which creates a risk to public health at all levels. Had the case gone to trial, EDF would have taken the position that Sec. 112 required a zero emission standard, the only standard adequate to provide the required margin of safety for a non-threshold pollutant. Instead, EDF settled for a compromise which establishes a goal of zero emissions and requires industry to move one step closer to that goal.

J.A. at 72-73. The EDF's comments contain other similar references, such as the assertion, in response to cost arguments raised by the industry, that "the statute EPA operates under requires regulations based on protection of health and not cost and technology concerns." Id. at 83. Thus, the EPA had before it the question of whether the statute permits considerations of cost and technology in setting standards, and it had the opportunity to consider that question in deciding to withdraw the proposed amendments.

The EPA also suggests, however, that we should be "especially" loath to allow this petition for review because the "NRDC chose not to participate at all in any of the administrative proceedings on vinyl chloride." Brief for EPA at 12 (emphasis in original). This merely restates the proposition that the NRDC has failed to exhaust its administrative remedies. None of the cases relied upon by the EPA suggests that exceptions to exhaustion have any less applicability in the case of a wholly absent party than in other exhaustion contexts. See Environmental Defense Fund v. EPA, 598 F.2d 62, 91 (D.C.Cir.1978); Nader v. Nuclear Regulatory Comm'n, 513 F.2d 1045, 1054-55 (D.C.Cir.1975). This is not a case in which the statute conditions a party's ability to obtain judicial review upon its participation in the rulemaking proceedings. See Gage v. Atomic Energy Comm'n, 479 F.2d 1214, 1218 (D.C.Cir.1973). The jurisdictional provision of the Clean Air Act imposes no such prerequisite, and, in fact, employs rather permissive language which does not specify who may bring a petition for review. See 42 U.S.C. Sec. 7607(b) (1982) ("A petition for review of action of the Administrator in promulgating ... any emission standard or requirement under section 7412 ... may be filed ... in the United States Court of Appeals for the District of Columbia."). The NRDC's total abstention from participation in the rulemaking proceedings does not make the exhaustion requirement more compelling or negate the valid exception to that requirement asserted by the NRDC.

The NRDC's challenge to the EPA's withdrawal of the 1977 amendments is simple: because the statute adopts an exclusive focus on considerations of health, the Administrator must set a zero level of emissions when he cannot determine that there is a level below which no harm will occur.

We must determine whether the EPA's actions are arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law. 42 U.S.C. Sec. 7607(d)(9)(A) (1982). Review begins with the question of whether "Congress has directly spoken to the precise question at issue" and has expressed a clear intent as to its resolution. Chevron, U.S.A., Inc. v. NRDC, 467 U.S. 837, 842-43, 104 S.Ct. 2778, 2781, 81 L.Ed.2d 694 (1984). If so, "that intention is the law and must be given effect." Id. at 843 n. 9, 104 S.Ct. at 2781 n. 9. "[I]f the statute is silent or ambiguous with respect to the specific issue," we must accept an agency interpretation if it is reasonable in light of the language, legislative history, and underlying policies of the statute. Id. at 843, 104 S.Ct. at 2782; NRDC v. Thomas, 805 F.2d 410, 420 (D.C.Cir.1986). We find no support in the text or legislative history for the proposition that Congress intended to require a complete prohibition of emissions whenever the EPA cannot determine a threshold level for a hazardous pollutant. Instead, there is strong evidence that Congress considered such a requirement and rejected it.

Section 112 commands the Administrator to set an "emission standard" for a particular "hazardous air pollutant" which in his "judgment" will provide an "ample margin of safety." Congress' use of the term "ample margin of safety" is inconsistent with the NRDC's position that the Administrator has no discretion in the face of uncertainty. The statute nowhere defines "ample margin of safety." The Senate Report, however, in discussing a similar requirement in the context of setting ambient air standards under section 109 of the Act, explained the purpose of the "margin of safety" standard as one of affording "a reasonable degree of protection ... against hazards which research has not yet identified." S.Rep. No. 1196, 91st Cong., 2d Sess. 10 (1970) (emphasis added). This view comports with the historical use of the term in engineering as "a safety factor ... meant to compensate for uncertainties and variabilities." See Hall, The Control of Toxic Pollutants Under the Federal Water Pollution Control Act Amendments of 1972, 63 Iowa L.Rev. 609, 629 (1978). Furthermore, in a discussion of the use of identical language in the Federal Water Pollution Control Act, this court has recognized that, in discharging the responsibility to assure "an ample margin of safety," the Administrator faces "a difficult task, indeed, a veritable paradox--calling as it does for knowledge of that which is unknown--[but] ... the term 'margin of safety' is Congress's directive that means be found to carry out the task and to reconcile the paradox." Environmental Defense Fund v. EPA, 598 F.2d 62, 81 (D.C.Cir.1978). And while Congress used the modifier "ample" to exhort the Administrator not to allow "the public [or] the environment ... to be exposed to anything resembling the maximum risk" and, therefore, to set a margin "greater than 'normal' or 'adequate,' " Congress still left the EPA "great latitude in meeting its responsibility." See id.

Congress' use of the word "safety," moreover, is significant evidence that it did not intend to require the Administrator to prohibit all emissions of non-threshold pollutants. As the Supreme Court has recently held, "safe" does not mean "risk-free." Industrial Union Dep't, AFL-CIO v. American Petroleum Inst., 448 U.S. 607, 642, 100 S.Ct. 2844, 2864, 65 L.Ed.2d 1010 (1980). Instead, something is "unsafe" only when it threatens humans with "a significant risk of harm." Id.

Thus, the terms of section 112 provide little support for the NRDC's position. The uncertainty about the effects of a particular carcinogenic pollutant invokes the Administrator's discretion under section 112. In contrast, the NRDC's position would eliminate any discretion and would render the standard "ample margin of safety" meaningless as applied to carcinogenic pollutants.1 Whenever any scientific uncertainty existed about the ill effects of a nonzero level of hazardous air pollutants--and we think it unlikely that science will ever yield absolute certainty of safety in an area so complicated and rife with problems of measurement, modeling, long latency, and the like--the Administrator would have no discretion but would be required to prohibit all emissions. Had Congress intended that result, it could very easily have said so by writing a statute that states that no level of emissions shall be allowed as to which there is any uncertainty. But Congress chose instead to deal with the pervasive nature of scientific uncertainty and the inherent limitations of scientific knowledge by vesting in the Administrator the discretion to deal with uncertainty in each case.

The NRDC also argues that the legislative history supports its position. To the contrary, that history strongly suggests that Congress did not require the Administrator to prohibit emissions of all non-threshold pollutants; Congress considered and rejected the option of requiring the Administrator to prohibit all emissions.

The Senate bill would have required the Administrator to prohibit any emission of a hazardous pollutant, threshold or non-threshold, unless he found, after a hearing, that a preponderance of the evidence demonstrated "that such agent is not hazardous to the health of persons" or that "departure from ... prohibition for [a] stationary source will not be hazardous to the health of persons." S. 4358, 91st Cong., 2d Sess. Sec. 6(b), 116 Cong.Rec. 32,375 (1970). The definition of hazardous agent included any pollutant "whose presence ... in trace concentrations in the ambient air ... causes or will cause, or contribute to, an increase in serious irreversible or incapacitating reversible damage to health." Id. Presumably, this provision would have required the complete prohibition of emissions of carcinogenic agents because the Administrator cannot demonstrate by "a preponderance of the evidence" that trace concentrations of these agents will not cause harm. The final version of section 112, however, omits any reference to a prohibition of emissions and directs the Administrator to set an emissions standard "at the level which in his judgment provides an ample margin of safety to protect the public health." Thus, Congress rejected a provision which would have required the Administrator to prohibit certain emissions and adopted a provision which places that decision within the Administrator's discretion.

The only arguable support for the NRDC's position is a passage in the summary of the provisions of the conference agreement attached to Senator Muskie's statement during the post-conference debate on the Clean Air Act:

The standards must be set to provide an ample margin of safety to protect the public health. This could mean, effectively, that a plant could be required to close because of the absence of control techniques. It could include emission standards which allow for no measurable emissions.

Senate Consideration of the Report of the Conference Committee, Exhibit 1 to Statement of Sen. Muskie, Congressional Research Service of the Library of Congress, 93d Cong., 2d Sess., 1 A Legislative History of the Clean Air Amendments of 1970 at 133 (Comm.Print 1974). This statement does not, as the NRDC supposes, mean that the Administrator must set a zero-emission level for all non-threshold pollutants. On its face, the statement means only that, in certain conditions, there may be plant closings and sometimes zero emissions may be required. Senator Muskie did not say this would invariably be so when scientific uncertainty existed. His statement confirms that the Administrator is permitted to set a zero-emission level for some pollutants; it does not hold that the Administrator is invariably required to do so whenever there is some scientific uncertainty.

It is also significant that this is the only reference after the Conference Committee compromise to the possibility of plant closure as a result of the Administrator's actions under section 112. To accept the petitioner's contention that section 112 requires the Administrator to prohibit all emissions of non-threshold pollutants, we would have to conclude that, without even discussing the matter, Congress mandated massive economic and social dislocations by shutting down entire industries. That is not a reasonable way to read the legislative history. The EPA has determined that a zero-emissions standard for non-threshold pollutants would result in the elimination of such activities as "the generation of electricity from either coal-burning or nuclear energy; the manufacturing of steel; the mining, smelting, or refining of virtually any mineral (e.g., copper, iron, lead, zinc, and limestone); the manufacture of synthetic organic chemicals; and the refining, storage, or dispensing of any petroleum product." National Emission Standards for Hazardous Air Pollutants; Policy and Procedures for Identifying, Assessing and Regulating Airborne Substances Posing a Risk of Cancer, 44 Fed.Reg. 58,642, 58,660 (1979). It is simply not possible that Congress intended such havoc in the American economy and not a single representative or senator mentioned the fact. Cf. Industrial Union Dep't, 448 U.S. at 645, 100 S.Ct. at 2865 ("In the absence of a clear mandate in the Act, it is unreasonable to assume that Congress intended to give the Secretary [this] unprecedented power over American industry."). Thus, we find no support for the NRDC's extreme position in the language or legislative history of the Act.

We turn now to the question whether the Administrator's chosen method for setting emission levels above zero is consistent with congressional intent. The Administrator's position is that he may set an emission level for non-threshold pollutants at the lowest level achievable by best available control technology when that level is anywhere below the level of demonstrated harm and the cost of setting a lower level is grossly disproportionate to the benefits of removing the remaining risk. The NRDC argues that this standard is arbitrary and capricious because the EPA is never permitted to consider cost and technological feasibility under section 112 but instead is limited to consideration of health-based factors. Thus, before addressing the Administrator's method of using cost and technological feasibility in this case, we must determine whether he may consider cost and technological feasibility at all. See Chemical Mfrs. Ass'n v. NRDC, 470 U.S. 116, 134, 105 S.Ct. 1102, 1112, 84 L.Ed.2d 90 (1985) (relevant issue is whether there is a clear congressional intent "to forbid" the challenged agency action).

On its face, section 112 does not indicate that Congress intended to preclude consideration of any factor. Though the phrase "to protect the public health" evinces an intent to make health the primary consideration, there is no indication of the factors the Administrator may or may not consider in determining, in his "judgment," what level of emissions will provide "an ample margin of safety." Instead, the language used, and the absence of any specific limitation, gives the clear impression that the Administrator has some discretion in determining what, if any, additional factors he will consider in setting an emission standard.

The petitioner argues that the legislative history makes clear Congress' intent to foreclose reliance on non-health-based considerations in setting standards under section 112. We find, however, that the legislative history can be characterized only as ambiguous.

The NRDC directs us to the hazardous air pollutants provision of the House bill, which states that "[i]f ... emissions [from any class of new stationary sources] are extremely hazardous to health, no new source of such emissions shall be constructed or operated, except where (and subject to such conditions as he deems necessary and appropriate) the [Administrator] makes a specific exemption with respect to such construction or operation." See H.R. 17255, 91st Cong., 2d Sess. Sec. 5(a), 116 Cong.Rec. 19,226 (1970). Thus, as to extremely hazardous emissions, the House bill granted the Administrator a rather open-ended power to exempt a source from the regulation imposed, a power that the petitioner presumes, probably correctly, to have allowed for exemptions on the basis of non-health considerations.2 By contrast, the petitioner notes, the Senate bill had a tight focus on health, prohibiting emissions "hazardous to the health of persons" and allowing only health-based exceptions to that prohibition. See S. 4358, 91st Cong., 2d Sess. Sec. 6(b), 116 Cong.Rec. 32,375 (1970). Because the final version that emerged from conference more closely resembled the Senate than the House bill, and because no express provision for any "specific exemption" survived, the NRDC argues that any feasibility considerations must have been deliberately eliminated. We find this reading of the legislative history strained.

While the original Senate bill is closer than the House bill to the final legislation, neither the House nor the Senate version closely resembles in the aspect relevant here the compromise that emerged from conference. H.R. 17255 dealt only with new stationary sources and, with respect to those, only half of the regulatory scheme dealt with emissions considered "extremely hazardous to health." See H.R. 17255, 91st Cong., 2d Sess. Sec. 5(a), 116 Cong.Rec. 19,225-26 (1970). The bill also dealt with new sources, the emissions of which could "contribute substantially to endangerment of the public health or welfare" but which were not "extremely hazardous to health," providing for control of such emissions "to the fullest