Opinion for the Court by Circuit Judge ROGERS.
Before the court are petitions for review of two final rules promulgated by the Environmental Protection Agency regarding the emission of hazardous air pollutants (“HAPs”) from electric utility steam generating units (“EGUs”). The first rule removes coal- and oil-fired EGUs from the list of sources whose emissions are regulated under section 112 of the Clean Air Act (“CAA”), 42 U.S.C. § 7412. Revision of December 2000 Regulatory Finding (“Delisting Rule”), 70 Fed.Reg. 15,994 (Mar. 29, 2005). The second rule sets performance standards pursuant to section 111, 42 U.S.C. § 7411, for new coal-fired EGUs and establishes total mercury emissions limits for States and certain tribal areas, along with a voluntary cap-and-trade program for new and existing coal-fired EGUs. Standards of Performance for New and Existing Stationary Sources: Electric Utility Steam Generating Units (“CAMR”), 70 Fed.Reg. 28,606 (May 18, 2005).
Petitioners contend that the Delisting Rule is contrary to the plain text and structure of section 112. In response, EPA and certain intervenors rely on section 112(n), which sets special conditions before EGUs can be regulated under sec
I.
In 1970, Congress added section 112 to the CAA. Pub.L. No. 91-604, § 4(a), 84 Stat. 1676, 1685 (1970). In its original form, section 112 required EPA to list HAPs that should be regulated because they could “cause, or contribute to, an increase in mortality or an increase in serious irreversible[ ] or incapacitating reversible[] illness.” Id. § 112(a)(1). Over the next eighteen years, however, EPA listed only eight HAPs, established standards for only seven of these and as to these seven addressed only a limited selection of possible pollution sources. See Nat’l Mining Ass’n v. EPA,
In 1990, Congress, concerned about the slow pace of EPA’s regulation of HAPs, altered section 112 by eliminating much of EPA’s discretion in .the process. See, e.g., Nat’l Lime Ass’n. v. EPA,
First, Congress required EPA to regulate more than one hundred specific HAPs, including mercury and nickel compounds. CAA § 112(b)(1). Further, EPA was required to list and to regulate, on a prioritized schedule, id. § 112(e)(l)-(3), “all categories and subcategories of major sources and areas sources” that emit one or more HAPs, id. § 112(c)(1). In seeking to ensure that regulation of HAPs reflects the “maximum .reduction in emissions which can be achieved by application of [the] best available control technology,” S.Rep. No. 101-228, at 133, reprinted in 1990 U.S.C.C.A.N. at 3518; see, e.g., CAA § 112(g)(2)(A), Congress imposed specific, strict pollution control requirements on both new and existing sources of HAPs. Congress specified that new sources must adopt at minimum “the emission control that is achieved in practice by the best controlled similar source, as determined by the Administrator.” Id. § 112(d)(3). Existing sources (with certain exceptions) must adopt emission controls equal to the “average emission limitation achieved by the best performing 12 percent of the existing sources.” Id. § 112(d)(3)(A).
Second, Congress restricted the' opportunities for EPA and others to intervene in the regulation of HAP sources. For HAPs .that result in health effects other than cancer, as is true of mercury, Congress directed that the Administrator “may delete any source category” from the section
Third, Congress required the Administrator to evaluate regulatory options with care and to meet certain conditions before listing EGUs as an HAP source under section 112(c)(1). Specifically:
[t]he Administrator shall perform a study of the hazards to public health reasonably anticipated to occur as a result of emissions by [EGUs] of pollutants listed under subsection (b) of this section after imposition of the requirements of this chapter. The Administrator shall report the results of this study to the Congress within 3 years after November 15, 1990. The Administrator shall develop and describe in the Administrator’s report to Congress alternative control strategies for emissions which may warrant regulation under this section. The Administrator shall regulate [EGUs] under this section, if the Administrator finds such regulation is appropriate and necessary after considering the results of the study required by this subparagraph.
Id. § 112(n)(l)(A) (emphasis added).
The study of public health hazards required by section 112(n)(l)(A) was finally completed in 1998. This study found “a plausible link between anthropogenic releases of mercury from industrial and combustion sources in the United States and methylmercury in fish” and that “mercury emissions from [EGUs] may add to the existing environmental burden.” EPA, Office of Air Quality Planning and Standards, Study of Hazardous Air Pollutant Emissions From Elec. Util. Steam Generating Units — Final Report to Cong. 7-1, 45 (1998). On December 20, 2000, the Administrator announced — in light of the study mandated by section 112(n)(l)(A), as well as subsequent information and consideration of alternative feasible control strategies — that it was “appropriate and necessary” to regulate coal- and oil-fired EGUs under section 112 because, as relevant, mercury emissions from EGUs, which are the largest domestic source of mercury emissions, present significant hazards to public health and the environment. Regulatory Finding on the Emissions of Hazardous Air Pollutants From Electric Utility Steam Generating Units, 65 Fed.Reg. 79,825, 79,827 (Dec. 20, 2000) (“2000 Determination”). “As a result the source category for Coal- and Oil-Fired [EGUs] was added to the list of source categories under section 112(c)” on December 20, 2000. National Emission Standards for Hazardous Air Pollutants: Revision of Source Category List Under Section 112 of the Clean Air Act (“2002 Notice of Listing”), 67 Fed.Reg. 6521, 6522, 6524 (Feb. 12, 2002).
In early 2004, EPA proposed two regulatory alternatives to control emissions from coal- and oil-fired EGUs. The first was similar to EPA’s proposal in 2000— regulation under section 112 through.issuance of Maximum Achievable Control Technology standards, see, e.g., CAA § 112(g)(2)(A), or implementation of a cap- and-trade system. The second proposed removing EGUs from the list of HAP sources prepared pursuant to section 112(c)(1) and instead regulating their emis
EPA justified its decision to delist EGUs by explaining that it “reasonably interprets section 112(n)(l)(A) as providing [] authority to remove coal- and oil-fired units from the section 112(c) list at any time that it makes a negative appropriate and necessary finding under the section.” Delisting Rule, 70 Fed.Reg. at 16,032. It based this interpretation on the “entirely different structure and predicate for assessing whether [EGUs] should be listed for regulation under section 112” as set forth in section 112(n)(l)(A), id., and on the absence of a temporal “deadline” for deciding “whether regulation of [EGUs was] appropriate and necessary” under section 112, id. at 16,001. It also interpreted “section 112(c)(9) [delisting] criteria ... not [to] apply” to EGUs because their inclusion in the list established by section 112(c)(1) was not a “final agency action[ ],” and claimed, contrary to the 2000 Determination, that “the source category at issue did not meet the statutory criteria for listing at the time of listing.” Id. at 16,-033.
Having decided that it possessed the authority to delist EGUs without making the findings required by section 112(c)(9), EPA explained that the delisting of EGUs was justified because their regulation under section 112 was neither “appropriate” nor “necessary.” The potential mercury emissions reductions achievable under CAMR figured prominently in EPA’s explanation of its delisting of coal-fired EGUs, id. at 16,005, which EPA promulgated in May 2005. CAMR established plant-specific “standards of performance” for mercury emissions from new coal-fired EGUs under section 111(b). 70 Fed.Reg. at 28,613-16. Relying on sections 111(b) and (d), it also established a national mercury emissions cap for new and existing EGUs, allocating each state and certain tribal areas a mercury emissions budget. This was supplemented by a voluntary cap-and-trade program. Id. at 28,616, 28,-622, 28,629.
New Jersey and fourteen additional States, the Michigan Department of Environmental Quality, the Pennsylvania Department of Environmental Protection, the City of Baltimore (“Government Petitioners”), and various environmental organizations (“Environmental Petitioners”) contend that EPA violated Section 112’s plain text and structure when it did not comply with the requirements of section 112(c)(9) in delisting EGUs. Because we agree, we do not reach then1 alternative contention that even if this delisting was lawful, EPA was arbitrary and capricious in reversing its determination that regulating EGUs under section 112 was “appropriate and necessary.” Government and Environmental Petitioners further contend that CAMR is inconsistent with provisions of section 111, and that both the Delisting Rule and CAMR should be vacated. Certain intervenors — including various industry representatives, States, and state agencies — -join EPA in urging the lawfulness of the two rules.
The court reviews the challenges to the final rules to determine whether EPA’s promulgation of them was arbitrary or capricious, an abuse of discretion, or otherwise not in accordance with law. See CAA § 307(d)(9)(A), 42 U.S.C. § 7607(d)(9)(A). Challenges to EPA’s interpretation of the CAA itself are governed by the familiar two-pronged test of Chevron, U.S.A., Inc. v. Natural Resources Defense Council, Inc.,
Petitioners contend that once the Administrator determined in 2000 that EGUs should be regulated under Section 112 and listed them under section 112(c)(1), EPA had no authority to delist them without taking the steps required under section 112(c)(9). We agree.
Section 112(c)(9) provides that:
The Administrator may delete any source category from the [section 112(c)(1) list] ... whenever the Administrator ... [determines] that emissions from no source in the category or subcategory concerned ... exceed a level which is adequate to protect public health with an ample margin of safety and no adverse environmental effect will result from emissions from any source, [emphasis added]
EPA offers several arguments in an attempt to evade section 112(c)(9)’s plain text, but they are not persuasive. First, EPA seeks to reach step two of Chevron and obtain judicial deference to its interpretation by maintaining that section 112(n)(l) makes section 112(c)(9) ambiguous because “[l]ogically, if EPA makes a determination under section 112(n)(l)(A) that power plants should not be regulated at all under section 112 ... [then] this determination ipso facto must result in removal of power plants from the section 112(c) list.” Resp’t Br. at 26. But this simply does not follow. Section 112(n)(l) governs how the Administrator decides whether to list EGUs; it says nothing about delisting EGUs, and the plain text of section 112(c)(9) specifies that it applies to the delisting of “any source.” In the context of the CAA, “the word ‘any’ has an expansive meaning.” New York v. EPA
Second, EPA maintains that it possesses authority to remove EGUs from the section 112 list under the “fundamental principle of administrative law that an agency has inherent authority to reverse an earlier administrative determination or ruling where an agency has a principled basis for doing so.” Resp’t Br. at 22 (citing Williams Gas Processing-Gulf Coast Co. v. FERC,
Finally, EPA states in its brief that it has previously removed sources listed under section 112(c) without satisfying the requirements of section 112(c)(9). But previous statutory violations cannot excuse the one now before the court. “[W]e do not see how merely applying an unreasonable statutory interpretation for several years can transform it into a reasonable interpretation.” F.J. Vollmer Co. v. Magaw,
Accordingly, in view of the plain text and structure of section 112, we grant the petitions and vacate the Delisting Rule. See Allied-Signal, Inc. v. U.S. Nuclear Regulatory Comm’n,
Notes
. Section 111 requires the Administrator to "establish[] ... standards of performance,” CAA § 111(b)(1)(B), for pollutants from new sources that in the Administrator's judgment "cause[], or contributed significantly to, air pollution which may reasonably be anticipated to endanger public health or welfare.” Id. § 111(b)(1)(A). "Standards of performance” are designed to limit emissions to reflect "the degree of emission limitation achievable through the application of the best system of emission reduction which (taking into account the cost of achieving such reduction and any nonair quality health and environmental impact and energy requirements) the Administrator determines has been adequately demonstrated.” Id. § 111(a)(1). Existing sources of pollutants are regulated under section 111 (d).
. Upon reconsideration, EPA made no substantive change to the Delisting Rule but revised CAMR’s State mercury allocations and the statistical analysis used for new source performance standards; EPA declined to stay CAMR. Revision of December 2000 Clean Air Act Section 112(n) Finding Regarding Electric Utility Steam Generating Units; and Standards of Performance for New and Existing Electric Utility Steam Generating Units: Reconsideration, 71 Fed.Reg. 33,388, 33,388-89, 33,395-96 (June 9, 2006).
. Certain intervenors also contend, citing Thomas v. New York,
