Full opinion text
Opinion for the Court filed PER CURIAM. PER CURIAM: Following the Supreme Court’s decision in Massachusetts v. EPA 549 U.S. 497, 127 S.Ct. 1438, 167 L.Ed.2d 248 (2007)— which clarified that greenhouse gases are an “air pollutant” subject to regulation under the Clean Air Act (CAA) — the Environmental Protection Agency promulgated a series of greenhouse gas-related rules. First, EPA issued an Endangerment Finding, in which it determined that greenhouse gases may “reasonably be anticipated to endanger public health or welfare.” See 42 U.S.C. § 7521(a)(1). Next, it issued the Tailpipe Rule, which set emission standards for cars and light trucks. Finally, EPA determined that the CAA requires major stationary sources of greenhouse gases to obtain construction and operating permits. But because immediate regulation of all such sources would result in overwhelming permitting burdens on permitting authorities and sources, EPA issued the Timing and Tailoring Rules, in which it determined that only the largest stationary sources would initially be subject to permitting requirements. Petitioners, various states and industry groups, challenge all these rules, arguing that they are based on improper constructions of the CAA and are otherwise arbitrary and capricious. But for the reasons set forth below, we conclude: 1) the Endangerment Finding and Tailpipe Rule are neither arbitrary nor capricious; 2) EPA’s interpretation of the governing CAA provisions is unambiguously correct; and 3) no petitioner has standing to challenge the Timing and Tailoring Rules. We thus dismiss for lack of jurisdiction all petitions for review of the Timing and Tailoring Rules, and deny the remainder of the petitions. I. We begin with a brief primer on greenhouse gases. As their name suggests, when released into the atmosphere, these gases act “like the ceiling of a greenhouse, trapping solar energy and retarding the escape of reflected heat.” Massachusetts v. EPA, 549 U.S. at 505,127 S.Ct. 1438. A wide variety of modern human activities result in greenhouse gas emissions; cars, power plants, and industrial sites all release significant amounts of these heat-trapping gases. In recent decades “[a] well-documented rise in global temperatures has coincided with a significant increase in the concentration of [greenhouse gases] in the atmosphere.” Id. at 504-05, 127 S.Ct. 1438. Many scientists believe that mankind’s greenhouse gas emissions are driving this climate change. These scientists predict that global climate change will cause a host of deleterious consequences, including drought, increasingly severe weather events, and rising sea levels. The genesis of this litigation came in 2007, when the Supreme Court held in Massachusetts v. EPA that greenhouse gases “unambiguous[ly]” may be regulated as an “air pollutant” under the Clean Air Act (“CAA”). Id. at 529, 127 S.Ct. 1438. Squarely rejecting the contention — then advanced by EPA — that “greenhouse gases cannot be ‘air pollutants’ within the meaning of the Act,” id. at 513, 127 S.Ct. 1438, the Court held that the CAA’s definition of “air pollutant” “embraces all airborne compounds of whatever stripe.” Id. at 529, 127 S.Ct. 1438 (emphasis added). Moreover, because the CAA requires EPA to establish motor-vehicle emission standards for “any air pollutant ... which may reasonably be anticipated to endanger public health or welfare,” 42 U.S.C. § 7521(a)(1) (emphasis added), the Court held that EPA had a “statutory obligation” to regulate harmful greenhouse gases. Id. at 534, 127 S.Ct. 1438. “Under the clear terms of the Clean Air Act,” the Court concluded, “EPA can avoid taking further action only if it determines that greenhouse gases do not contribute to climate change or if it provides some reasonable explanation as to why it cannot or will not exercise its discretion to determine whether they do.” Id. at 533, 127 S.Ct. 1438. The Court thus directed EPA to determine “whether sufficient information exists to make an endangerment finding” for greenhouse gases. Id. at 534, 127 S.Ct. 1438. Massachusetts v. EPA spurred a cascading series of greenhouse gas-related rules and regulations. First, in direct response to the Supreme Court’s directive, EPA issued an Endangerment Finding for greenhouse gases. , Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act (“Endangerment Finding”), 74 Fed. Reg. 66,496 (Dec. 15, 2009). The Endangerment Finding defined as a single “air pollutant” an “aggregate group of six long-lived and directly-emitted greenhouse gases” that are “well mixed” together in the atmosphere and cause global climate change: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Id. at 66,-536-37. Following “common practice,” EPA measured the impact of these gases on a “carbon dioxide equivalent basis,” (C02e) which is based on the gases’ “warming effect relative to carbon dioxide ... over a specified timeframe.” Id. at 66,519. (Using the carbon dioxide equivalent equation, for example, a mixture of X amount of nitrous oxide and Y amount of sulfur hexafluoride is expressed as Z amount of C02e). After compiling and considering a considerable body of scientific evidence, EPA concluded that motor-vehicle emissions of these six well-mixed gases “contribute to the total greenhouse gas air pollution, and thus to the climate change problem, which is reasonably anticipated to endanger public health and welfare.” Id. at 66,499. Next, and pursuant to the CAA’s requirement that EPA establish motor-vehicle emission standards for “any air pollutant ... which may reasonably be anticipated to endanger public health or welfare,” 42 U.S.C. § 7521(a)(1), the agency promulgated its Tailpipe Rule for greenhouse gases. Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards; Final Rule (“Tailpipe Rule”), 75 Fed. Reg. 25,324 (May 7, 2010). Effective January 2, 2011, the Tailpipe Rule set greenhouse gas emission standards for cars and light trucks as part of a joint rulemaking with fuel economy standards issued by the National Highway Traffic Safety Administration (NHTSA). Id. at 25,326. Under EPA’s longstanding interpretation of the CAA, the Tailpipe Rule automatically triggered regulation of stationary greenhouse gas emitters under two separate sections of the Act. The first, the Prevention of Significant Deterioration of Air Quality (PSD) program, requires state-issued construction permits for certain types of stationary sources — for example, iron and steel mill plants — if they have the potential to emit over 100 tons per year (tpy) of “any air pollutant.” See 42 U.S.C. §§ 7475; 7479(1). All other stationary sources are subject to PSD permitting if they have the potential to emit over 250 tpy of “any air pollutant.” Id. § 7479(1). The second provision, Title V, requires state-issued operating permits for stationary sources that have the potential to emit at least 100 tpy of “any air pollutant.” Id. § 7602(j). EPA has long interpreted the phrase “any air pollutant” in both these provisions to mean any air pollutant that is regulated under the CAA. See Requirements for Preparation, Adoption, and Submittal of Implementation Plans; Approval and Promulgation of Implementation Plans (“1980 Implementation Plan Requirements”), 45 Fed. Reg. 52,676, 52,-711 (Aug. 7, 1980) (PSD program); Prevention of Significant Deterioration and Title V Greenhouse Gas Tailoring Rule (“Tailoring Rule”), 75 Fed. Reg. 31,514, 31,553-54 (June 3, 2010) (discussing history of Title V regulation and applicability). And once the Tailpipe Rule set motor-vehicle emission standards for greenhouse gases, they became a regulated pollutant under the Act, requiring PSD and Title V greenhouse permitting. Acting pursuant to this longstanding interpretation of the PSD and Title V programs, EPA issued two rules phasing in stationary source greenhouse gas regulation. First, in the Timing Rule, EPA concluded that an air pollutant becomes “subject to regulation” under the Clean Air Act — and thus subject to PSD and Title V permitting — only once a regulation requiring control of that pollutant takes effect. Reconsideration of Interpretation of Regulations That Determine Pollutants Covered by Clean Air Act Permitting Programs (“Timing Rule”), 75 Fed. Reg. 17,004 (Apr. 2, 2010). Therefore, EPA concluded, major stationary emitters of greenhouse gases would be subject to PSD and Title V permitting regulations on January 2, 2011 — the date on which the Tailpipe Rule became effective, and thus, the date when greenhouse gases first became regulated under the CAA. Id. at 17,019. Next, EPA promulgated the Tailoring Rule. In the Tailoring Rule, EPA noted that greenhouse gases are emitted in far greater volumes than other pollutants. Indeed, millions of industrial, residential, and commercial sources exceed the 100/250 tpy statutory emissions threshold for C02e. Tailoring Rule, 75 Fed. Reg. at 31,534-36. Immediately adding these sources to the PSD and Title V programs would, EPA predicted, result in tremendous costs to industry and state permitting authorities. See id. As a result, EPA announced that it was “relieving overwhelming permitting burdens that would, in the absence of this rule, fall on permitting authorities and sources.” Id. at 31,516. Departing from the CAA’s 100/250 tpy emissions threshold, the Tailoring Rule provided that only the largest sources — those exceeding 75,000 or 100,000 tpy C02e, depending on the program and project — would initially be subject to greenhouse gas permitting. Id. at 31,523. (The Tailoring Rule further provided that regulated sources must also emit greenhouse gases at levels that exceed the 100/250 tpy emissions threshold on a mass basis. That is, they must emit over 100/250 tpy of actual pollutants, in addition to exceeding the 75,000/100,000 tpy carbon dioxide equivalent. Id. at 31,-523.) A number of groups — including states and regulated industries — filed petitions for review of EPA’s greenhouse gas regulations, contending that the agency misconstrued the CAA and otherwise acted arbitrarily and capriciously. This appeal consolidates the petitions for review of the four aforementioned rules: the Endangerment Finding, the Tailpipe Rule, the Timing Rule, and the Tailoring Rule. “The Clean Air Act empowers us to reverse the Administrator’s action in rule-making if it is ‘arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with the law.’ ” Med. Waste Inst. & Energy Recovety Council v. EPA, 645 F.3d 420, 424 (D.C.Cir.2011) (quoting 42 U.S.C. § 7607(d)(9)(A)). Questions of statutory interpretation are governed by the familiar Chevron two-step: “First ... if the intent of Congress is clear, that is the end of the matter; for the court, as well as the agency, must give effect to the unambiguously expressed intent of Congress.” Chevron, U.S.A. Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 842-43, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984). But “if the statute is silent or ambiguous with respect to the specific issue, the question for the court is whether the agency’s answer is based on a permissible construction of the statute.” Id. at 843, 104 S.Ct. 2778. This opinion proceeds in several steps. Part II explains why the Endangerment Finding was neither arbitrary nor capricious, while Part III does the same for the Tailpipe Rule. Turning to stationary source regulation, Part IV examines whether any petitioners may timely challenge EPA’s longstanding interpretation of the PSD statute. Because we conclude that they may, Part V addresses the merits of their statutory arguments, and explains why EPA’s interpretation of the CAA was compelled by the statute. Next, Part VI explains why petitioners lack standing to challenge the Timing and Tailoring Rules themselves. Finally, Part VII disposes of several arguments that have nothing to do with the rules under review, and thus are not properly before us. II. We turn first to State and Industry Petitioners’ challenges to the Endangerment Finding, the first of the series of rules EPA issued after the Supreme Court remanded Massachusetts v. EPA In the decision ordering the remand, the Supreme Court held that EPA had failed in its statutory obligations when it “offered no reasoned explanation for its refusal to decide whether greenhouse gases cause or contribute to climate change.” Massachusetts v. EPA 549 U.S. at 534, 127 S.Ct. 1438. On remand, EPA compiled a substantial scientific record, which is before us in the present review, and determined that “greenhouse gases in the atmosphere may reasonably be anticipated both to endanger public health and to endanger public welfare.” Endangerment Finding, 74 Fed. Reg. at 66,497. EPA went on to find that motor-vehicle emissions of greenhouse gases “contribute to the total greenhouse gas air pollution, and thus to the climate change problem, which is reasonably anticipated to endanger public health and welfare.” Id. at 66,499. State and Industry Petitioners challenge several aspects of EPA’s decision, including (1) EPA’s interpretation of CAA § 202(a)(1), which sets out the endangerment-finding standard; (2) the adequacy of the scientific record supporting the Endangerment Finding; (3) EPA’s decision not to “quantify” the risk of endangerment to public health or welfare created by climate change; (4) EPA’s choice to define the “air pollutant” at issue as an aggregate of six greenhouse gases; (5) EPA’s failure to consult its Science Advisory Board before issuing the Endangerment Finding; and (6) EPA’s denial of all petitions for reconsideration of the Endangerment Finding. We ultimately conclude that the Endangerment Finding is consistent with Massachusetts v. EPA and the text and structure of the CAA, and is adequately supported by the administrative record. A. Industry Petitioners contend that EPA improperly interpreted CAA § 202(a)(1) as restricting the Endangerment Finding to a science-based judgment devoid of considerations of policy concerns and regulatory consequences; They assert that CAA § 202(a)(1) requires EPA to consider, e.g., the benefits of activities that require greenhouse gas emissions, the effectiveness of emissions regulation triggered by the Endangerment Finding, and the potential for societal adaptation to or mitigation of climate change. They maintain that eschewing those considerations also made the Endangerment Finding arbitrary and capricious. These contentions are foreclosed by the language of the statute and the Supreme Court’s decision in Massachusetts v. EPA. Section 202(a) of the CAA states in relevant part that EPA’s Administrator shall by regulation prescribe (and from time to time revise) in accordance with the provisions of this section, standards applicable to the emission of any air pollutant from any class or classes of new motor vehicles or new motor vehicle engines, which in his judgment cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare. 42 U.S.C. § 7521(a)(1). This language requires that the endangerment evaluation “relate to whether an air pollutant ‘cause[s], or contribute^ to, air pollution which may reasonably be anticipated to endanger public health or welfare.’ ” Massachusetts v. EPA, 549 U.S. at 532-33, 127 S.Ct. 1438. At bottom, § 202(a)(1) requires EPA to answer only two questions: whether particular “air pollution” — here, greenhouse gases — “may reasonably be anticipated to endanger public health or welfare,” and whether motor-vehicle emissions “cause, or contribute to” that endangerment. These questions require a “scientific judgment” about the potential risks greenhouse gas emissions pose to public health or welfare — not policy discussions. Massachusetts v. EPA 549 U.S. at 534, 127 S.Ct. 1438. In Massachusetts v. EPA the Supreme Court rebuffed an attempt by EPA itself to inject considerations of policy into its decision. At the time, EPA had “offered a laundry list of reasons not to regulate” greenhouse gases, including that a number of voluntary Executive Branch programs already provide an effective response to the threat of global warming, that regulating greenhouse gases might impair the President’s ability to negotiate with “key developing nations” to reduce emissions, and that curtailing motor-vehicle emissions would reflect “an inefficient, piecemeal approach to address the climate change issue.” Id. at 533, 127 S.Ct. 1438 (citations omitted). The Court noted that “these policy judgments ... have nothing to do with whether greenhouse gas emissions contribute to climate change. Still less do they amount to a reasoned justification for declining to form a scientific judgment.” Id. at 533-34, 127 S.Ct. 1438. In the Court’s view, EPA’s policy-based explanations contained “no reasoned explanation for [EPA’s] refusal to decide” the key part of the endangerment inquiry: “whether greenhouse gases cause. or contribute to climate change.” Id. at 534, 127 S.Ct. 1438. As in Massachusetts v. EPA a “laundry list of reasons not to regulate” simply has “nothing to do with whether greenhouse gas emissions contribute to climate change.” Id. at 533-34, 127 S.Ct. 1438. The additional exercises State and Industry Petitioners would have EPA undertake — e.g., performing a cost-benefit analysis for greenhouse gases, gauging the effectiveness of whatever emission standards EPA would enact to limit greenhouse gases, and predicting society’s adaptive response to the dangers or harms caused by climate change — do not inform the “scientific judgment” that § 202(a)(1) requires of EPA. Instead of focusing on the question whether greenhouse gas emissions may reasonably be anticipated to endanger public health or welfare, the factors State and Industry Petitioners put forth only address what might happen were EPA to answer that question in the affirmative. As EPA stated in the Endangerment Finding, such inquiries “muddle the rather straightforward scientific judgment about whether there may be endangerment by throwing the potential impact of responding to the danger into the initial question.” 74 Fed. Reg. at 66,515. To be sure, the subsection following § 202(a)(1), § 202(a)(2), requires that EPA address limited questions about the cost of compliance with new emission standards and the availability of technology for meeting those standards, see infra Part III, but these judgments are not part of the § 202(a)(1) endangerment inquiry. The Supreme Court made clear in Massachusetts v. EPA that it was not addressing the question “whether policy concerns can inform EPA’s actions in the event that it makes such a finding,” 549 U.S. at 534-35, 127 S.Ct. 1438, but that policy concerns were not part of the calculus for the determination of the endangerment finding in the first instance. The Supreme Court emphasized that it was holding “that EPA must ground its reasons for action or inaction in the statute.” Id. at 535, 127 S.Ct. 1438. The statute speaks in terms of endangerment, not in terms of policy, and EPA has complied with the statute. State and Industry Petitioners insist that because statutes should be interpreted to avoid absurd results, EPA should have considered at least the “absurd” consequences that would follow from an endangerment finding for greenhouse gases. Specifically: having made an endangerment finding, EPA will proceed to promulgate emission standards under § 202(a)(1). Issuing those standards triggers regulation — under EPA’s PSD and Title V programs — of stationary sources that emit greenhouse gases at levels above longstanding statutory thresholds. Because greenhouse gases are emitted in much higher volumes than other air pollutants, hundreds of thousands of small stationary sources would exceed those thresholds. This would subject those sources to PSD and Title V permitting requirements despite what Petitioners claim was Congress’s clear intent that the requirements apply only to large industrial sources. Petitioners assert that even EPA believed such overbroad regulation to be an absurd result, which it attempted to rectify by adopting the Tailoring Rule to raise the statutory thresholds, see infra Part VI. However “absurd” Petitioners consider this consequence, though, it is still irrelevant to the endangerment inquiry. That EPA adjusted the statutory thresholds to accommodate regulation of greenhouse gases emitted by stationary sources may indicate that the CAA is a regulatory scheme less-than-perfectly tailored to dealing with greenhouse gases. But the Supreme Court has already held that EPA indeed wields the authority to regulate greenhouse gases under the CAA. See Massachusetts v. EPA. The plain language of § 202(a)(1) of that Act does not leave room for EPA to consider as part of the endangerment inquiry the stationary-source regulation triggered by an endangerment finding, even if the degree of regulation triggered might at a later stage be characterized as “absurd.” B. State and Industry Petitioners next challenge the adequacy of the scientific record underlying the Endangerment Finding, objecting to both the type of evidence upon which EPA relied and EPA’s decision to make an Endangerment Finding in light of what Industry Petitioners view as significant scientific uncertainty. Neither objection has merit. 1. As an initial matter, State and Industry Petitioners question EPA’s reliance on “major assessments” addressing greenhouse gases and climate change issued by the Intergovernmental Panel on Climate Change (IPCC), the U.S. Global Climate Research Program (USGCRP), and the National Research Council (NRC). Endangerment Finding, 74 Fed. Reg. at 66,-510-11. These peer-reviewed assessments synthesized thousands of individual studies on various aspects of greenhouse gases and climate change and drew “overarching conclusions” about the state of the science in this field. Id. at 66,511. The assessments provide data and information on, inter alia, “the amount of greenhouse gases being emitted by human activities”; their continued accumulation in the atmosphere; the resulting observed changes to Earth’s energy balance, temperature and climate at global and regional levels, and other “climate-sensitive sectors and systems of the human and natural environment”; the extent to which these changes “can be attributed to human-induced buildup of atmospheric greenhouse gases”; “future projected climate change”; and “projected risks and impacts to human health, society and the environment.” Id. at 66,510-11. State and Industry Petitioners assert that EPA improperly “delegated” its judgment to the IPCC, USGCRP, and NRC by relying on these assessments of climate-change science. See U.S. Telecom Ass’n v. FCC, 359 F.3d 554, 566 (D.C.Cir.2004). This argument is little more than a semantic trick.. EPA did not delegate, explicitly or otherwise, any decision-making to any of those entities. EPA simply did here what it and other decision-makers often must do to make a science-based judgment: it sought out and reviewed existing scientific evidence to determine whether a particular finding was warranted. It makes no difference that much of the scientific evidence in large part consisted of “syntheses” of individual studies and research. Even individual studies and research papers often synthesize past work in an area and then build upon it. This is how science works. EPA is not required to re-prove the existence of the atom every time it approaches a scientific question. Moreover, it appears from the record that EPA used the assessment reports not as substitutes for its own judgment but as evidence upon which it relied to make that judgment. EPA evaluated the processes used to develop the various assessment reports, reviewed their contents, and considered the depth of the scientific consensus the reports represented. Based on these evaluations, EPA determined the assessments represented the best source material to use in deciding whether greenhouse gas emissions may be reasonably anticipated to endanger public health or welfare. Endangerment Finding, 74 Fed. Reg. at 66,510-11. It then reviewed those reports along with comments relevant to the scientific considerations involved to determine whether the evidence warranted an endangerment finding for greenhouse gases as it was required to do under the Supreme Court’s mandate in Massachusetts v. EPA 2. Industry Petitioners also assert that the scientific evidence does not adequately support the Endangerment Finding. As we have stated before in reviewing the science-based decisions of agencies such as EPA, “[ajlthough we perform a searching and careful inquiry into the facts underlying the agency’s decisions, we will presume the validity of agency action as long as a rational basis for it is presented.” Am. Farm Bureau Fed’n v. EPA 559 F.3d 512, 519 (D.C.Cir.2009) (internal quotation marks omitted). In so doing, “we give an extreme degree of deference to the agency when it is evaluating scientific data within its technical expertise.” Id. (internal quotation marks omitted). The body of scientific evidence marshaled by EPA in support of the Endangerment Finding is substantial. EPA’s scientific evidence of record included support for the proposition that greenhouse gases trap heat on earth that would otherwise dissipate into space; that this “greenhouse effect” warms the climate; that human activity is contributing to increased atmospheric levels of greenhouse gases; and that the climate system is warming. Based on this scientific record, EPA made the linchpin finding: in its judgment, the “root cause” of the recently observed climate change is “very likely” the observed increase in anthropogenic greenhouse gas emissions. Endangerment Finding, 74 Fed. Reg. at 66,518. EPA found support for this finding in three lines of evidence. First, it drew upon our “basic physical understanding” of the impacts of various natural and manmade changes on the climate system. For instance, EPA relied on evidence that the past half-century of warming has occurred at a time when natural forces such as solar and volcanic activity likely would have produced cooling. Endangerment Finding, Response to Comments (RTC) Vol. 3, at 20. Other evidence supports EPA’s conclusion that the observed warming pattern — warming of the bottommost layer of the atmosphere and cooling immediately above it — is consistent with greenhouse-gas causation. Id. EPA further relied upon evidence of historical estimates of past climate change, supporting EPA’s conclusion that global temperatures over the last half-century are unusual. Endangerment Finding, 74 Fed. Reg. at 66,518. Scientific studies upon which EPA relied place high confidence in the assertion that global mean surface temperatures over the last few decades are higher than at any time in the last four centuries. Technical Support Document for the Endangerment Finding (TSD), at 31. These studies also show, albeit with significant uncertainty, that temperatures at many individual locations were higher over the last twenty-five years than during any period of comparable length since 900 A.D. Id. For its third line of evidence that anthropogenic emissions of greenhouse gases spurred the perceived warming trend, EPA turned to computer-based climate-model simulations. Scientists have used global climate models built on basic principles of physics and scientific knowledge about the climate to try to simulate the recent climate change. These models have only been able to replicate the observed warming by including anthropogenic emissions of greenhouse gases in the simulations. Endangerment Finding, 74 Fed. Reg. at 66,523. To recap, EPA had before it substantial record evidence that anthropogenic emissions of greenhouse gases “very likely” caused warming of the climate over the last several decades. EPA further had evidence of current and future effects of this warming on public health and welfare. Relying again upon substantial scientific evidence, EPA determined that anthropogenically induced climate change threatens both public health and public welfare. It found that extreme weather events, changes in air quality, increases in food- and water-borne pathogens, and increases in temperatures are likely to have adverse health effects. Id. at 66,497-98. The record also supports EPA’s conclusion that climate - change endangers human welfare by creating risk to food production and agriculture, forestry, energy, infrastructure, ecosystems, and wildlife. Substantial evidence further supported EPA’s conclusion that the warming resulting from the greenhouse gas emissions could be expected to create risks to water resources and in general to coastal areas as a result of expected increase in sea level. Id. at 66,-498. Finally, EPA determined from substantial evidence that motor-vehicle emissions of greenhouse gases contribute to climate change and thus to the endangerment of public health and welfare. Industry Petitioners do not find fault with much of the substantial record EPA amassed in support of the Endangerment Finding. Rather, they contend that the record evidences too much uncertainty to support that judgment. But the existence of some uncertainty does not, without more, warrant invalidation of an endangerment finding. If a statute is “precautionary in nature” and “designed to protect the public health,” and the relevant evidence is “difficult to come by, uncertain, or conflicting because it is on the frontiers of scientific knowledge,” EPA need not provide “rigorous step-by-step proof of cause and effect” to support an endangerment finding. Ethyl Corp. v. EPA, 541 F.2d 1, 28 (D.C.Cir.1976). As we have stated before, “Awaiting certainty will often allow for only reactive, not preventive, regulation.” Id. at 25. Congress did not restrict EPA to remedial regulation when it enacted CAA § 202(a). That section mandates that EPA promulgate new emission standards if it determines that the air pollution at issue “may reasonably be anticipated to endanger public health or welfare.” 42 U.S.C. § 7521(a)(1). This language requires a precautionary, forward-looking scientific judgment about the risks of a particular air pollutant, consistent with the CAA’s “precautionary and preventive orientation.” Lead Indus. Ass’n, Inc. v. EPA, 647 F.2d 1130, 1155 (D.C.Cir.1980). Requiring that EPA find “certain” endangerment of public health or welfare before regulating greenhouse gases would effectively prevent EPA from doing the job Congress gave it in § 202(a) — utilizing emission standards to prevent reasonably anticipated endangerment from maturing into concrete harm. Cf. id. (“[Requiring EPA to wait until it can conclusively demonstrate that a particular effect is adverse to health before it acts is inconsistent with both the [CAAj’s precautionary and preventive orientation and the nature of the Administrator’s statutory responsibilities. Congress provided that the Administrator is to use his judgment in setting air quality standards precisely to permit him to act in the face of uncertainty.”). In Massachusetts v. EPA the Supreme Court confirmed that EPA may make an endangerment finding despite lingering scientific uncertainty. Indeed, the Court held that the existence of “some residual uncertainty” did not excuse EPA’s decision to decline to regulate greenhouse gases. Massachusetts v. EPA 549 U.S. at 534, 127 S.Ct. 1438. To avoid regulating emissions of greenhouse gases, EPA would need to show “scientific uncertainty ... so profound that it precludes EPA from making a reasoned judgment as to whether greenhouse gases contribute to global warming.” Id. Clearly, then, EPA may issue an endangerment finding even while the scientific record still contains at least “some residual uncertainty.” Industry Petitioners have shown no more than that. In the end, Petitioners are asking us to re-weigh the scientific evidence before EPA and reach our own conclusion. This is not our role. As with other reviews of administrative proceedings, we do not determine the convincing force of evidence, nor the conclusion it should support, but only whether the conclusion reached by EPA is supported by substantial evidence when considered on the record as a whole. See, e.g., New York v. EPA 413 F.3d 3, 30 (D.C.Cir.2005). When EPA evaluates scientific evidence in its bailiwick, we ask only that it take the scientific record into account “in a rational manner.” Am. Petroleum Inst. v. Costle, 665 F.2d 1176, 1187 (D.C.Cir.1981). Industry Petitioners have not shown that EPA failed to do so here. C. State Petitioners, here led by Texas, contend that the Endangerment Finding is arbitrary and capricious because EPA did not “define,” “measure,” or “quantify” either the atmospheric concentration at which greenhouse gases endanger public health or welfare, the rate or type of climate change that it anticipates will endanger public health or welfare, or the risks or impacts of climate change. According to Texas, without defining these thresholds and distinguishing “safe” climate change from climate change that endangers, EPA’s Endangerment Finding is just a “subjective conviction.” It is true that EPA did not provide a quantitative threshold at which greenhouse gases or climate change will endanger or cause certain impacts to public health or welfare. The text of CAA § 202(a)(1) does not require that EPA set a precise numerical value as part of an endangerment finding. Quite the opposite; the § 202(a)(1) inquiry necessarily entails a case-by-case, sliding-scale approach to endangerment because “[d]anger ... is not set by a fixed probability of harm, but rather is composed of reciprocal elements of risk and harm, or probability and severity.” Ethyl, 541 F.2d at 18. EPA need not establish a minimum threshold of risk or harm before determining whether an air pollutant endangers. It may base an endangerment finding on “a lesser risk of greater harm ... or a greater risk of lesser harm” or any combination in between. Id Ethyl is instructive. There, EPA made an endangerment finding for airborne lead. During its endangerment inquiry, EPA initially tried to do what Texas asks of it here: find a specific concentration of the air pollutant below which it would be considered “safe” and above which it would endanger public health. Id at 56. However, EPA abandoned that approach because it failed to account for “the wide variability of dietary lead intake” and lacked predictive value. EPA substituted a “more qualitative” approach, which relied on “predictions based on uncertain data” along with clinical studies. Id at 56-57. This court upheld the endangerment finding that used that qualitative approach despite the lack of a specific endangerment “threshold.” In its essence, Texas’s call for quantification of the endangerment is no more than a specialized version of Industry Petitioners’ claim that the scientific record contains too much uncertainty to find endangerment. EPA relied on a substantial record of empirical data and scientific evidence, making many specific and often quantitative findings regarding the impacts of greenhouse gases on climate change and the effects of climate change on public health and welfare. Its failure to distill this ocean of evidence into a specific number at which greenhouse gases cause “dangerous” climate change is a function of the precautionary thrust of the CAA and the multivariate and sometimes uncertain nature of climate science, not a sign of arbitrary or capricious decision-making. D. EPA defined both the “air pollution” and the “air pollutant” that are the subject of the Endangerment Finding as an aggregate of six greenhouse gases, which EPA called “well mixed greenhouse gases”: carbon dioxide (C02), methane (CH4), nitrous oxide (N20), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). Industry Petitioners argue that EPA’s decision to include PFCs and SF6 in this group of greenhouse gases was arbitrary and capricious primarily because motor vehicles generally do not emit these two gases. No petitioner for review of the Endangerment Finding has established standing to make this argument. Industry Petitioners concede that EPA’s decision to regulate PFCs and SF6 along with the other four greenhouse gases does not injure any motor-vehicle-related petitioner. Nor has any non-motor-vehicle-related petitioner shown an injury-in-fact resulting from EPA’s inclusion of these two gases in the six-gas amalgam of “well-mixed greenhouse gases.” At oral argument, Industry Petitioners asserted for the first time that certain utility companies — members of associations that petitioned for review of the Endangerment Finding — own utility transformers that emit SF6. However, they never demonstrated or even definitively asserted that any of these companies would not be subject to regulation or permitting requirements but for EPA’s decision to include SF6 as part of the “well-mixed greenhouse gases” that are the subject of the Endangerment Finding. See Sierra Club v. EPA, 292 F.3d 895, 898-900 (D.C.Cir.2002) (requiring that a petitioner seeking review of agency action demonstrate standing by affidavit or other evidence if standing is not “self-evident” from the administrative record). Absent a petitioner with standing to challenge EPA’s inclusion of PFCs and SF6 in the “air pollution” at issue, this court lacks jurisdiction to address the merits of Industry Petitioners’ contention. E. EPA did not submit the Endangerment Finding for review by its Science Advisory Board (SAB). Industry Petitioners claim that EPA’s failure to do so violates its mandate to “make available” to the SAB “any proposed criteria document, standard, limitation, or regulation under the Clean Air Act” at the time it provides the same “to any other Federal agency for formal review and comment.” 42 U.S.C. § 4365(c)(1); see Am. Petroleum Inst., 665 F.2d at 1188. To begin with, it is not clear that EPA provided the Endangerment Finding “to any other Federal agency for formal review and comment,” which triggers this duty to submit a regulation to the SAB. EPA only submitted a draft of the Endangerment Finding to the Office of Information and Regulatory Affairs pursuant to Executive Order 12,866. EPA contends that this was merely an informal review process, not “formal review and comment” — at least when compared with a statutory review-and-comment requirement in which other agencies are given the opportunity to provide written comments about the impacts of a proposed regulation on the reviewing agency’s universe of responsibility. See, e.g., 49 U.S.C. § 32902(j). Industry Petitioners failed to respond to this contention. In any event, even if EPA violated its mandate by failing to submit the Endangerment Finding to the SAB, Industry Petitioners have not shown that this error was “of such central relevance to the rule that there is a substantial likelihood that the rule would have been significantly changed if such errors had not been made.” 42 U.S.C. § 7607(d)(8); see Am. Petroleum Inst., 665 F.2d at 1188-89 (applying this standard to EPA’s failure to submit an ozone standard to the SAB). F. Lastly, State Petitioners maintain that EPA erred by denying all ten petitions for reconsideration of the Endangerment Finding. Those petitions asserted that internal e-mails and documents released from the University of East Anglia’s Climate Research Unit (CRU) — a contributor to one of the global temperature records and to the IPCC’s assessment report— undermined the scientific evidence supporting the Endangerment Finding by calling into question whether the IPCC scientists adhered to “best science practices.” EPA’s Denial of the Petitions To Reconsider the Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act (“Reconsideration Denial”), 75 Fed. Reg. 49,556, 49,556-57 (Aug. 13, 2010). The petitions pointed to factual mistakes in the IPCC’s assessment report resulting from the use of non-peer-reviewed studies and several scientific studies postdating the Endangerment Finding as evidence that the Endangerment Finding was flawed. Id. On August 13, 2010, EPA issued a denial of the petitions for reconsideration accompanied by a 360-page response to petitions (RTP). Id. at 49,556. It determined that the petitions did not provide substantial support for the argument that the Endangerment Finding should be revised. According to EPA, the petitioners’ claims based on the CRU documents were exaggerated, contradicted by other evidence, and not a material or reliable basis for questioning the credibility of the body of science at issue; two of the factual inaccuracies alleged in the petitions were in fact mistakes, but both were “tangential and minor” and did not change the key IPCC conclusions; and the new scientific studies raised by some petitions were either already considered by EPA, misinterpreted or misrepresented by petitioners, or put forth without acknowledging other new studies. Id. at 49,557-58. 1. EPA is required to convene a proceeding for reconsideration of a rule if a party raising an objection to the rule can demonstrate to the Administrator that it was impracticable to raise such objection within such time or if the grounds for such objection arose after the period for public comment (but within the time specified for judicial review) and if such objection is of central relevance to the outcome of the rule. 42 U.S.C. § 7607(d)(7)(B). For the purpose of determining whether to commence reconsideration of a rule, EPA considers an objection to be of “central relevance to the outcome” of that rule “if it provides substantial support for the argument that the regulation should be revised.” Reconsideration Denial, 75 Fed. Reg. at 49,561. State Petitioners have not provided substantial support for their argument that the Endangerment Finding should be revised. State Petitioners point out that some studies the IPCC referenced in its assessment were not peer-reviewed, but they ignore the fact that (1) the IPCC assessment relied on around 18,000 studies that were peer-reviewed, and (2) the IPCC’s report development procedures expressly permitted the inclusion in the assessment of some non-peer-reviewed studies (“gray” literature). Moreover, as EPA determined, the limited inaccurate information developed from the gray literature does not appear sufficient to undermine the substantial overall evidentiary support for the Endangerment Finding. State Petitioners have not, as they assert, uncovered a “pattern” of flawed science. Only two of the errors they point out seem to be errors at all, and EPA relied on neither in making the Endangerment Finding. First, as State Petitioners assert, the IPCC misstated the percentage of the Netherlands that is below sea level, a statistic that was used for background information. However, the IPCC corrected the error, and EPA concluded that the error was “minor and had no impact,” and the Endangerment Finding did not refer to the statistic in any way. Id. at 49,576-77. Second, the IPCC acknowledged misstating the rate at which Himalayan glaciers are receding. EPA also did not rely on that projection in the Endangerment Finding. Id. at 49,577. State Petitioners also contend that a new study contradicts EPA’s reliance on a projection of more violent storms in the future as a result of climate change, but the study they cite only concerns past trends, not projected future storms. The record shows that EPA considered the new studies on storm trends and concluded that the studies were consistent with the Endangerment Finding. In sum, State Petitioners have failed to show that these isolated “errors” provide substantial support for their argument to overturn the Endangerment Finding. 2. State Petitioners’ further argument that EPA erred in denying reconsideration fails as well. These Petitioners claim EPA erred by failing to provide notice and comment before denying the petitions for reconsideration because EPA’s inclusion of a 360-page RTP amounted to a revision of the Endangerment Finding, and revision of a rule requires notice and comment. The RTP, however, appears to be exactly what EPA called it — a response to the petitions for reconsideration, not a revision of the Endangerment Finding itself. EPA certainly may deny petitions for reconsideration of a rule and provide an explanation for that denial, including by providing support for that decision, without triggering a new round of notice and comment for the rule. III. State and Industry Petitioners contend that in promulgating the Tailpipe Rule, EPA relied on an improper interpretation of CAA § 202(a)(1), and was arbitrary and capricious in failing to justify and consider the cost impacts of its conclusion that the Rule triggers stationary-source regulation under the PSD and Title V provisions. They do not challenge the substantive standards of the Rule and focus principally on EPA’s failure to consider the cost of stationary-source permitting requirements triggered by the Rule. Positing an absurd-consequences scenario, Petitioners maintain that if EPA had considered these costs it “would have been forced” to exclude carbon dioxide from the scope of the emission standards, to decline to issue greenhouse gas emission standards at all, or “to interpret the statute so as not to automatically trigger stationary source regulation.” Industry Tailpipe Br. 17; see also Industry Tailpipe Reply Br. 8-9. Both the plain text of Section 202(a) and precedent refute Petitioners’ contentions. A. Section 202(a)(1) provides: The Administrator shall by regulation prescribe ... standards applicable to the emission of any air pollutant from any class or classes of new motor vehicles or new motor vehicle engines, which in his judgment cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare. 42 U.S.C. § 7521(a)(1). By employing the verb “shall,” Congress vested a non-discretionary duty in EPA. See Sierra Club v. Jackson, 648 F.3d 848, 856 (D.C.Cir.2011). The plain text of Section 202(a)(1) thus refutes Industry Petitioners’ contention that EPA had discretion to defer issuance of motor-vehicle emission standards on the basis of stationary-source costs. Neither the adjacent text nor the statutory context otherwise condition this clear “language of command,” id. (citation omitted). Having made the Endangerment Finding pursuant to CAA § 202(a), 42 U.S.C. § 7521(a), EPA lacked discretion to defer promulgation of the Tailpipe Rule on the basis of its trigger of stationary-source permitting requirements under the PSD program and Title V. The Supreme Court’s decision in Massachusetts v. EPA compels this interpretation of Section 202(a)(1). “If EPA makes a finding of endangerment, the Clean Air Act requires the [a]gency to regulate emissions of the deleterious pollutant from new motor vehicles.” 549 U.S. at 533, 127 S.Ct. 1438. “Under the clear terms of the Clean Air Act, EPA can avoid taking further action only if it determines that greenhouse gases do not contribute to climate change or if it provides some reasonable explanation as to why it cannot or will not exercise its discretion to determine whether they do.” Id. (emphasis added). In the Endangerment Finding, EPA determined that motor-vehicle emissions contribute to greenhouse gas emissions that, in turn, endanger the public health and welfare; the agency therefore was in no position to “avoid taking further action,” id., by deferring promulgation of the Tailpipe Rule. Given the non-discretionary duty in Section 202(a)(1) and the limited flexibility available under Section 202(a)(2), which this court has held relates only to the motor-vehicle industry, see infra Part III.C, EPA had no statutory basis on which it could “ground [any] reasons for” further inaction, Massachusetts v. EPA, 549 U.S. at 535, 127 S.Ct. 1438. The plain text of Section 202(a)(1) also negates Industry Petitioners’ contention that EPA had discretion to defer the Tailpipe Rule on the basis of NHTSA’s authority to regulate fuel economy. The Supreme Court dismissed a near-identical argument in Massachusetts v. EPA, rejecting the suggestion that EPA could decline to regulate carbon-dioxide emissions because the Department of Transportation (DOT) had independent authority to set fuel-efficiency standards. Id. at 531-32, 127 S.Ct. 1438. “[T]hat DOT sets mileage standards in no way licenses EPA to shirk its environmental responsibilities,” because EPA’s duty to promulgate emission standards derives from “a statutory obligation wholly independent of DOT’s mandate to promote energy efficiency.” Id. at 532, 127 S.Ct. 1438. Just as EPA lacks authority to refuse to regulate on the grounds of NHTSA’s regulatory authority, EPA cannot defer regulation on that basis. A comparison of the relevant statutes bolsters this conclusion. Compare 49 U.S.C. § 32902(f) (“When deciding maximum feasible average fuel economy ..., the Secretary of Transportation shall consider ... the effect of other motor vehicle standards of the Government on fuel economy....”), with 42 U.S.C. § 7521(a) (including no such direction). Nor, applying the same reasoning, was EPA required to treat NHTSA’s proposed regulations as establishing the baseline for the Tailpipe Rule. Furthermore, the Tailpipe Rule provides benefits above and beyond those resulting from NHTSA’s fuel-economy standards. See, e.g., Tailpipe Rule, 75 Fed. Reg. at 25,490 (Table III.F.1-2), 25,636 (Table IV.G.1-4). Petitioners’ related contentions regarding the PSD permitting triggers are addressed in Part V. B. Turning to the APA, Industry Petitioners contend, relying on Small Refiner Lead Phase-Down Task Force v. EPA, 705 F.2d 506, 525 (D.C.Cir.1983), and Ethyl Corp. v. EPA, 541 F.2d 1 (D.C.Cir.1976), that EPA failed both to justify the Tailpipe Rule in terms of the risk identified in the Endangerment Finding and to show that the proposed standards “would meaningfully mitigate the alleged endangerment,” Industry Tailpipe Br. 35. Instead, they maintain that EPA “separated these two integral steps,” id. at 11, and “concluded that it had no obligation to show ... ‘the resulting emissions control strategy or strategies will have some significant degree of harm reduction or effectiveness in addressing the endangerment,’ ” id. at 11-12 (quoting Endangerment Finding, 74 Fed. Reg. at 66,508). These contentions fail. Petitioners’ reliance on Small Refiner, 705 F.2d at 525, is misplaced; the court there laid out guidelines for assessing EPA’s discretion to set numerical standards and Petitioners do not challenge the substance of the emission standards. In Ethyl, 541 F.2d at 7, the court assessed the scope of EPA’s authority, under CAA § 211(c)(1), 42 U.S.C. § 1857f-6c(c)(1) (1970) (currently codified as amended at 42 U.S.C. § 7545(c)(1)), to regulate lead particulate in motor-vehicle emissions. The court rejected the argument that the regulations had to “be premised upon factual proof of actual harm,” Ethyl, 541 F.2d at 12, and instead deferred to EPA’s reasonable interpretation that regulations could be based on a “significant risk of harm,” id. at 13. Nothing in Ethyl implied that EPA’s authority to regulate was conditioned on evidence of a particular level of mitigation; only a showing of significant contribution was required. EPA made such a determination in the Endangerment Finding, concluding that vehicle emissions are a significant contributor to domestic greenhouse gas emissions. See, e.g., Endangerment Finding, 74 Fed. Reg. at 66,499. Further, in the preamble to the Tailpipe Rule itself, EPA found that the emission standards would result in meaningful mitigation of greenhouse gas emissions. For example, EPA estimated that the Rule would result in a reduction of about 960 million metric tons of C02e emissions over the lifetime of the model year 2012-2016 vehicles affected by the new standards. See Tailpipe Rule, 75 Fed. Reg. at 25,488-90. Other precedent is likewise unhelpful to Petitioners: in Chemical Manufacturers Association v. EPA 217 F.3d 861, 866 (D.C.Cir.2000), “nothing in the record” indicated that the challenged regulatory program would “directly or indirectly, further the Clean Air Act’s environmental goals,” whereas here the record is fulsome, see supra Part II. C. Petitioners also invoke Section 202(a)(2) as support for their contention that EPA must consider stationary-source costs in the Tailpipe Rule. Section 202(a)(2) provides: Any regulation prescribed under paragraph (1) of this subsection ... shall take effect after such period as the Administrator finds necessary to permit the development and application of the requisite technology, giving appropriate consideration to the cost of compliance within such period. 42 U.S.C. § 7521(a)(2). State Petitioners maintain the reference to compliance costs encompasses those experienced by stationary sources under the PSD program, while Industry Petitioners maintain stationary-source costs are a relevant factor in EPA’s Section 202(a)(1) rulemaking. This court, however, has held that the Section 202(a)(2) reference to compliance costs encompasses only the cost to the motor-vehicle industry to come into compliance with the new emission standards, and does not mandate consideration of costs to other entities not directly subject to the proposed standards. See Motor & Equip. Mfrs. Ass’n, Inc. v. EPA 627 F.2d 1095, 1118 (D.C.Cir.1979). D. Petitioners’ remaining challenges to the Tailpipe Rule fail as well. In Part II, the court rejects the contention that the Tailpipe Rule fails due to flaws in the underlying Endangerment Finding. The record also refutes Industry Petitioners’ suggestion that EPA “employed a shell game to avoid,” Industry Tailpipe Reply Br. 9 (capitalization removed), responding to comments regarding stationary-source costs. Industry Tailpipe Br. 19-20; see also Industry Tailpipe Reply Br. 14-15. EPA adequately responded to “significant comments,” 42 U.S.C. § 7607(d)(6)(B). See, e.g., Tailpipe Rule, 75 Fed. Reg. at 25,401-02; Tailpipe Rule, Response to Comments at 7-65 to 7-69. And, assuming other statutory mandates provide a basis for judicial review, see Industry Tailpipe Br. 21-22 (listing mandates); see, e.g., Small Refiner, 705 F.2d at 537-39, the record shows EPA’s compliance, see Tailpipe Rule, 75 Fed. Reg. at 25,539-42, and that EPA was not arbitrary and capricious by not considering stationary-source costs in its analyses. See, e.g., Michigan v. EPA 213 F.3d 663, 689 (D.C.Cir.2000); Mid-Tex Elec. Coop., Inc. v. FERC, 773 F.2d 327, 341-42 (D.C.Cir.1985). EPA’s economic impact assessment conducted pursuant to CAA § 317, 42 U.S.C. § 7617, does not provide grounds for granting the petitions because Petitioners’ contentions that EPA, “[i]n defiance of these requirements, ... refused to estimate or even consider the costs of the [Tailpipe Rule] for stationary sources,” Industry Tailpipe Br. 22, are no more than another attempt to avoid the plain text of Section 202(a). See also 42 U.S.C. § 7617(e). IV. We turn next to the stationary source regulations. As noted supra in Part I, EPA’s interpretation of the CAA requires PSD and Title V permits for stationary sources whose potential emissions exceed statutory thresholds for any regulated pollutant — including greenhouse gases. Industry Petitioners now challenge EPA’s longstanding interpretation of the scope of the permitting requirements for construction and modification of major emitting facilities under CAA Sections 165(a) and 169(1), 42 U.S.C. §§ 7475(a) & 7479(1) (“the PSD permitting triggers”). EPA maintains that this challenge is untimely because its interpretation of the PSD permitting triggers was set forth in its 1978, 1980, and 2002 Rules. In 1978, EPA defined “major stationary source” as a source that emits major amounts of “any air pollutant regulated under the [CAA].” Part 51 — Requirements for Preparation, Adoption, and Submittal of Implementation Plans; Prevention of Significant Air Quality Deterioration (“1978 Implementation Plan Requirements”), 43 Fed. Reg. 26,380, 26,382 (June 19, 1978). Industry petitioners’ challenge to the 1978 Rule in Alabama Power Co. v. Costle, 636 F.2d 323 (D.C.Cir.1980) reflected their understanding that EPA would apply the PSD permitting program to both pollutants regulated pursuant to National Ambient Air Quality Standards (NAAQS) and other regulated pollutants. See Br. for Industry Pet’rs on Regulation of Pollutants other than Sulfur Dioxide and Particulates, No. 78-1006 (and consolidated cases) (Dec. 19, 1978) at 10, 12. In the 1980 Rule, EPA highlighted that to be subject to PSD review, a “source need only emit any pollutant in major amounts (i.e., the amounts specified in [CAA § 169(1)]) and be located in an area designated attainment or unclassifiable for that or any other pollutant.” 1980 Implementation Plan Requirements, 45 Fed. Reg. at 52,711 (emphasis in original). EPA explained that “any pollutant” meant “both criteria pollutants, for which national ambient air quality standards have been promulgated, and non-criteria pollutants subject to regulation under the Act.” Id. The same explanation of EPA’s interpretation appeared in the 2002 Rule. Prevention of Significant Deterioration and Nonattainment New Source Review, 67 Fed. Reg. 80,186, 80,-239-40, 80,264 (Dec. 31, 2002). CAA Section 307(b)(1) provides that a petition for review of any promulgated nationally applicable regulations: “shall be filed within sixty days from the date notice of such promulgation ... 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. § 7607(b)(1). -The exception encompasses the occurrence of an event that ripens a claim. See Chamber of Commerce v. EPA 642 F.3d 192, 208 n. 14 (D.C.Cir.2011); Am. Rd. & Transp. Builders Ass’n v. EPA 588 F.3d 1109, 1113 (D.C.Cir. 2009). EPA acknowledges this precedent, but maintains that the “new grounds” exception is narrow and inapplicable because Industry Petitioners’ challenge to EPA’s interpretation of the PSD permitting triggers is based on legal arguments that were available during the normal judicial review periods for the 1978, 1980, and 2002 Rules, and the “new ground” on which they now rely is a factual development, namely the regulation of greenhouse gases by the Tailpipe Rule. This is correct so far as it goes, but fails to demonstrate that Industry Petitioners’ challenge is untimely. Industry Petitioners point out that two petitioners — the National Association of Home Builders (NAHB) and National Oilseed Processors Association (NOPA)— have newly ripened claims as a result of the Tailpipe Rule, which had the effect of expanding the PSD program to never-regulated sources: • NAHB’s members construct single family homes, apartment buildings, and commercial buildings. According to the Vice President of Legal Affairs, prior to the Tailpipe Rule, no member of NAHB was a major source of any regulated pollutant, and thus no member was ever required to obtain a PSD permit. Decl. of Thomas J. Ward, Vice President of Legal Affairs for NAHB, ¶ 6 (May 10, 2011). Since the Tailpipe Rule rendered greenhouse gases a regulated pollutant, it is now certain that NAHB members that engage in construction projects that emit greenhouse gases in major amounts will have to obtain PSD permits sometime in the future. Id. at ¶¶ 7, 8. Indeed, EPA estimated that 6,397 multifamily buildings and 515 single family homes would trigger PSD review annually absent the Tailoring Rule. See Prevention of