Opinion for the Court filed by Chief Judge GINSBURG.
Thе United Mine Workers of America petitions for review of a final decision of the Mine Safety and Health Administration (MSHA), a component of the Department of Labor, to withdraw its proposed Air Quality rule. The Union argues the agency’s аction was contrary to the Federal Mine Safety and Health Act of 1977, 30 U.S.C. § 811, and arbitrary and capricious, in violation of the Administrative Procedure Act, 5 U.S.C. § 706(2)(A). Because we conclude the MSHA failed to provide an adequate explanation for its decision, we grant the Union’s petition and remand this matter to the agency for further proceedings-
I. Background
The Mine Safety and Health Act authorizes the Secretary of Labor to promulgate health standards “dealing with toxic materials or harmful physical agents” in order to protect miners from any “material .impairment of health or functional capacity.” 30 U.S.C. § 811(a)(6)(A). Pursuant to this authority, in 1989 the MSHA proposed a comprehensive rule that would: (1) “establish lists of hazardous substances that may adversely affect health and ... require control of exposure to such substances”; (2) “establish permissible exposure limits [PELs] and delineate the methods and frequency of monitoring to evaluate exposure”; and (3) “revise requirements for respiratory protection programs for metal/nonmetal mines and establish similar requirements for coal mines.” Ar Quality, Chemical Substances, and Respiratory Protection Standards, Proposed Rule, 54 Fеd.Reg. 35760, 35761/2 (Aug. 29, 1989). The rule would have, among other things, established PELs for more than 600 chemical substances that might be present in a mine, 165 of which substances would have been regulated for the first time. See id. at 35766/3, Table 2. As explained in the proposal:
The effect of these substances may range from allergic reactions to systemic toxicity- Some of them are capable of .causing cancers, central and peripheral neuropathies, lung disease, liver and kidney damage, birth defects, and other systemic effects.
54 Fed.Reg. at 35761/1.
Whеn it proposed the rule, the MSHA “believe[ed] that the health evidence form[ed] a reasonable basis for proposing *42 revisions to [current exposure] levels.” Id. Accordingly, the agency conducted public hearings, solicited and received comments, and in 1994 adopted one phase of the rule. See Air Quality: Health Standards for Abrasive Blasting and Drill Dust Control, Final Rule, 59 Fed.Reg. 8318 (Feb. 18, 1994), codified at 30 C.F.R. §§ 58.610-.620, 72.610-.630; see also Air Quality Proposed Rule, 54 Fed.Reg. at 35776/1-77/1.
In September 2002, however, the MSHA decided to withdraw the remainder of the proposed rule. 67 Fed.Reg. 60611 (Sept. 26, 2002). By way of explanation, the agency said its decision to withdraw the proposed rule “was the result of changes in agency priorities and the possible adverse effect ... of the decision in
AFL-CIO et. al. v. OSHA,” id.
at 60611/2, in which the Eleventh Circuit had invalidated an OSHA rule thаt set new PELs for 428 toxic substances,
see
II. Analysis
The Union first argues the MSHA’s withdrawal of the proposed Air Quality rule was contrary to the Mine Safety and Health Act. We review the MSHA’s interpretation of the Act according to the familiar standards in
Chevron U.S.A. Inc. v. Natural Resources Def. Council, Inc.,
A. Jurisdiction
We note at the outset that the source of our jurisdiction to entertain the Union’s petition, though the parties did not question it, is far from obvious. We therefore raised the issue ourselves and directed the parties to address it at oral argument.
See Citizens for Abatement of Aircraft Noise, Inc. v. Metro. Wash. Airports Auth.,
The Mine Safety аnd Health Act grants the court of appeals jurisdiction to entertain challenges only to any “mandatory health or safety standard promulgated under” the Act. 30 U.S.C. § 811(d).
*
The Union’s petition, however, challenges the withdrawal, rather than the promulgation, of a proposed rule; the Act does not grant this court jurisdiction to review such a challenge. It is equally clear the APA does not confer jurisdiction upon this (or any) court.
See Califano v. Sanders,
Under the All Writs Act, 28 U.S.C. § 1651(a), however, we have the authority to compel agency action unreasonably withheld or delayed if the putative agency action, once forthcoming, would be reviewable in this Court.
See Telecomm. Research & Action v. FCC,
This case, however, does not fall squarely under any circuit precedent because it is not a claim of unreasonable delay.
See id.
at 74;
OCAW,
Because the Mine Safety and Health Act expressly provides for review of promulgated standаrds in the court of appeals, one might infer that the court of appeals is without jurisdiction to review the Secretary’s decision not to promulgate a standard. If § 811(d) were construed by negative implication to preclude such review in the court of appeals, however, then an adversely affected party would have to seek review of the agency’s action, if at all, in the district court, pursuant to 28 U.S.C. § 1381 (federal question jurisdiction). It would be anomalоus, however, for the district court to review claims of arbitrary and capricious withdrawal while the court of appeals entertains claims of unreasonable delay, considering that the latter type of claim is at least as likely as the former to involve issues of fact. Our jurisdiction over claims of delay having been established in TRAC, that is, our authority to hear the Union’s claim that the proposed rule was unlawfully withdrawn seems to follow as a necessary implication. And so to the merits.
B. Statutory Authority
The Union first argues the MSHA’s decision to withdraw the proposed rule was contrary to the Mine Safety and Health Act itself: “once the Secretary identified the need to promulgate an air quality rule, she had the affirmative duty to complete it.” This argument need not detain us long, for it is perfectly clear the Secretary may withdraw a proposed “health or safety standard [if he] publishes] his reasons for his determination” not to promulgate it. 30 U.S.C. § 811(a)(4)(C). Thus, the Cоngress “has directly spoken to the precise question at issue,”
Chevron,
C. The Administrative Procedure Act
The Union next argues the MSHA’s decision to withdraw its proposed rule was not a reasoned one. We review the agency’s action under the deferential “arbitrary and capricious” standard of the APA.
See Nat’l Mining Ass’n v. MSHA,
Athough the MSHA’s publication of the proposed Ar Quality rule certainly did not obligate it to adopt that rule (or,
*44
for that matter, any rule), the agency “was not free to terminate the rulemaking for no reason whatsoever.”
Id.
at 446. Because “[t]he grounds upon which an administrative action must be judged are those upon which the record discloses that [the] action was based,”
SEC v. Chenery Corp.,
The MSHA purported to rest its decision upon three seemingly independent grounds: a “change in agency priorities”; the “possible adverse effect” of
AFL-CIO v. OSHA,
We are left with the MSHA’s claim that, in the wake of AFL-CIO v. OSHA, “a comprehensive approach to rulemaking” is “no longer a viable means” of addressing the health risks it had sought to remedy with thе proposed Air Quality rule. * 67 Fed.Reg. at 60611/2. In AFL-CIO v. OSHA, the MSHA explained, the court of appeals invalidated an OSHA rule because the agency had “not met its statutory burden in establishing the PELs for each of the 428 contaminants regulated by the standard.” Id. The case is indeed a caution for an agency embarking upon the regulation of exposure to numerous substances. That is why the MSHA, in 1996, said it was “exploring issuing the final [Air Quality] rule in phases”; at that time it apparently believed it could thereby meet the rеquirements elaborated by the Eleventh Circuit. Dep’t of Labor (Mine Safety & Health Administration) Unified Agenda, 61 Fed.Reg. 23261/3 (May 13, 1996). Yet, in later withdrawing the proposed Air Quality rule, the MSHA did not explain why it came to deem the Eleventh Circuit decision fatal to thаt effort. Nor did the agency address certain data submitted by the American Conference of Governmental Industrial Hygienists (ACGIH), which the Union suggests would have aided the agency in crafting a rule that met the Eleventh Circuit’s standard.
Even, if the agency had not raised the possibility of going forward in a manner designed to cope with the decision of the Eleventh Circuit, however, we would still have to remand this matter to the agency for further consideration. Two of the three reasons it gave still wоuld not sup
*45
port its decision, and we do not know — nor are we free to guess — what the agency would have done had it realized that it could not justify its decision by conclusorily asserting that agency priorities had changed or by observing that the record had become stale.
See Chenery I,
In sum, the MSHA failed to provide an adequate explanation for its decision to withdraw the Air Quality proposal. Absent such an explanation, the agency’s action was arbitrary and capricious.
III. Conclusion
For the forеgoing reasons, we grant the Union’s petition for review and remand this matter to the Mine Safety and Health Administration so that it may either proceed with the Air Quality rulemaking or give a reasoned account of its decision not to do so.
So ordered.
Notes
30 U.S.C. § 811(d) reads in relevant part:
Any рerson who may be adversely affected by a mandatory health or safety standard promulgated under this section may, at any time prior to the sixtieth day after such standard is promulgated, file a petition challenging the validity of such mаndatory standard with the United States Court of Appeals for the District of Columbia Circuit or the circuit wherein such person resides or has his principal place of business, for a judicial review of such standard.
We do not express an opinion with regard to whether "a comprehensive approach to rule-making” is still viable in light of
AFL-CIO v. OSHA. Cf. Troy Corp. v. Browner,