Will EPA Establish National Ambient Air Quality Standards for Greenhouse Gases?

Photo Credit: Getty

Will the Environmental Protection Agency (EPA) propose to establish national ambient air quality standards (NAAQS) for carbon dioxide (CO2) and other greenhouse gases (GHGs)? The question naturally arises given the Biden administration’s ambition to “put the United States on an irreversible path to a net-zero [GHG emission] economy by 2050” and Senate Democrats’ historic reluctance to vote for the “bold and ambitious” climate policies they profess to support.

A more particular circumstance also raises the question. On March 4, acting EPA Administrator Jane Nishida withdrew Trump EPA administrator Andrew Wheeler’s January 19 denial of a petition, submitted in December 2009 by the Center for Biological Diversity (CBD), to set NAAQS for GHGs.

Outside experts offer diverse opinions as to why the EPA is now cozying up to a petition it ignored for seven years during the first and second Obama-Biden administrations. See: “EPA Reopens Consideration of National Climate Pollution Cap” (CBD Press Release, 5 March); “Biden EPA Ponders ‘Hail Mary’ Move on Greenhouse Gas Air Limits” (Bloomberg Energy, 12 March); and “Whiff of the Unthinkable at EPA: CO2 Standards for States” (E&E News, 17 March).

The Biden team’s knee-jerk opposition to any policy bearing the Trump label may be a factor. Tactical considerations may also play a part. A NAAQS for CO2 set at 350 parts per million (ppm), as CBD proposes, would be economically devastating. Reviving the specter of this regulatory Sword of Damocles could spur capital flight from fossil fuel industries. The EPA could also threaten to initiate a NAAQS rulemaking if Senate Republicans block Green New Deal-style climate legislation.

The two articles and press release linked above quote Nishida’s explanation: The Trump EPA “did not fully and fairly assess the issues raised in the petition.” Really? Wheeler’s review of three GHG regulatory petitions, including CBD’s, is 19 single-spaced pages long. Nishida’s entire critique of Wheeler’s denial is limited to the 12 words quoted above. Wheeler’s assessment is certainly fuller and fairer than the silent treatment CBD got from the EPA during the Obama-Biden years.   

Wheeler’s Argument

Wheeler’s denial of the CBD petition was his last significant policy decision as EPA administrator. It deserves more analysis and commentary than Nishida’s dismissive one-sentence remark quoted in the press. I aim to supply that here.

Wheeler argues that he must deny the CBD petition because setting NAAQS for GHGs “would be inconsistent with the text and structure of the Clean Air Act (CAA).” He also outlines five policy considerations that support his decision. For example, NAAQS regulation of GHGs would undercut U.S. leverage in climate negotiations because adopting and implementing a NAAQS cannot be made “contingent on the actions of foreign countries.” Wheeler’s discussion of policy implications is of secondary importance and very accessible, so I won’t say more about it.

Statutory Text

CBD petitioned the EPA to set “national pollution standards” for GHGs under CAA § 108. “For the purpose of establishing [NAAQS],” Wheeler explains, quoting the statute, CAA § 108 provides that the EPA “shall” from time to time revise a list of air pollutants, known as “criteria pollutants.” But only if three conditions are met.

The conditions are set forth in subparts (A), (B), and (C) of the provision. First, emissions of the pollutant, in the administrator’s judgment, must cause or contribute to air pollution, “which may reasonably be anticipated to endanger public health of welfare.” CAA § 108(a)(1)(A). Second, the air pollution must “result from numerous or diverse mobile or stationary sources.” CAA § 108(a)(1)(B). Third, the pollutant must be one “for which [the administrator] plans to issue air quality criteria under this section.” CAA § 108(a)(1)(C).

Air quality criteria are documents that assess the latest scientific information about a pollutant’s health and welfare effects, which are the central criteria on which the EPA is to base air quality standards. As Wheeler notes, Congress originally identified five criteria pollutants: carbon monoxide, ground-level ozone, particulate matter, nitrogen dioxide, and sulfur dioxide. “To date, EPA has added only one to the list: lead.”

According to CBD, the EPA must establish NAAQS for GHGs because the agency concluded, in its December 2009 endangerment finding, that “greenhouse gas air pollution” endangers public health and welfare, and that the rise in atmospheric concentration results from numerous and diverse mobile and stationary sources.

The problem, Wheeler contends, is that CBD “effectively reads the third condition out of the statute.” Under subpart (C), the EPA may list a pollutant only if it is one for which the administrator “plans” to issue air quality criteria. No EPA administrator has ever planned to issue criteria for GHGs.

CBD relies for its legal interpretation on Natural Resources Defense Council (NRDC) v. Russell Train, a 1976 case decided by the Second Circuit Court of Appeals. EPA administrator Russell Train concluded that lead pollution from numerous sources endangered public health and welfare. However, he preferred to reduce lead emissions via CAA § 211, which regulates motor fuels and additives, and declined to issue air quality criteria for lead. The court agreed with the NRDC that Train had a mandatory duty to regulate lead under the NAAQS program.

Wheeler rebuts the court’s reasoning. In CAA § 108(a), subpart (C) is one of three conditions that must be satisfied prior to listing a pollutant for NAAQS regulation. The court, partly on the basis of legislative history, decided that subpart (C) is either ambiguous or a drafting error.

In fact, Wheeler avers, the meaning of subpart (C) is clear and the provision helps safeguard the reasonableness of the NAAQS program. It gives the administrator discretion to consider whether the NAAQS regime is the appropriate framework for regulating a pollutant from multiple sources. He explains: “A pollutant that cannot plausibly be controlled under the NAAQS regime should not be the subject of air quality criteria, and when the Administrator does not plan to issue criteria for a pollutant, it should not be listed, according to the plain language of the statute.”

Wheeler also disputes the court’s use of legislative history. Yes, some legislators in 1970 assumed the “EPA would issue a long list of criteria pollutants (‘fluorides, nitrogen oxides, polynuclear organic matter, lead, and odors’) within 30 days of passage,” as the court noted. But the NAAQS regime in practice has not worked that way. In the 45 years since NRDC v. Train was decided, “Lead remains the only criteria pollutant EPA has added to the original list of five. It is clearly not the case that every dangerous pollutant that originates from multiple sources must be added to the list of criteria pollutants.”

In addition, Wheeler points out, statutory interpretation that “looks for meaning first in legislative history and only secondarily in the words of the statute has fallen out of favor with the courts in the intervening decades as inconsistent with the judicial role.” As the Supreme Court recently stated: “It is ultimately the provisions of our laws rather than the principal concerns of our legislators by which we are governed.”

The court, in NRDC v. Train, also opined that making NAAQS regulation contingent on the administrator’s “plan” to issue air quality criteria would render the mandatory language of CAA § 108 “mere surplusage” and make the statutory timetable for attainment an “exercise in futility.” That assessment is no longer credible. Even though no criteria pollutants have been added to the list since 1977, the timetable “continues to drive state and federal action in response to EPA’s increasingly stringent NAAQS for the six existing criteria pollutants.”


The structure of the NAAQS program, with its local attainment and non-attainment areas, and five- to 10-year deadlines, has no rational application to gases evenly dispersed across the globe and persisting in the ambient air for decades to centuries.

The NAAQS regime is designed for local air pollution that state-level regulation can meaningfully control. In contrast, GHGs are mixed throughout the global atmosphere. Consequently, “No state implementation plan [SIP] could possibly have any measurable effect on the concentration of GHG within its own borders, and no state could ever come into attainment, on the basis of state-level action, with CBD’s preferred level of 350 parts per million (ppm) CO2 or any other standard set below current global concentrations.”

Establishing a CO2 NAAQS of 350 ppm would turn the United States into a single giant non-attainment area. Non-attainment would, for all practical purposes, be “perpetual,” given that CO2 levels are expected to reach 430-480 ppm in 2100 even under RCP2.6, the Intergovernmental Panel on Climate Change’s (IPCC) most stringent mitigation scenario (IPCC, Summary for Policy Makers, p. 18). Yet each state would face penalties, such as loss of highway funding grants, for failing to attain the unattainable within 10 years. CAA § 179(b)(1).

One might object that a 350 ppm CO2 NAAQS would not literally require states to reduce global CO2 concentrations to that level within 10 years. Under CAA § 179B, a state is deemed compliant if its implementation plan would be sufficient to attain and maintain the applicable NAAQS “but for emissions emanating from outside the United States.” For example, a CO2 NAAQS would not compel states to offset China’s emissions, only to make proportionate contributions to meeting the target.

That argument is unavailing, Wheeler explains. No state could demonstrate that its SIP would attain and maintain the NAAQS “by the attainment date” but for emissions emanating from beyond its borders. “Even if all the foreign countries in the world were to immediately cease anthropogenic emissions of GHG, it is unlikely that a hypothetical NAAQS would be attained by the attainment date, due to the long atmospheric lifetime of GHG and the comparatively high contribution of GHG from natural sources.”

Other structural incompatibilities identified by Wheeler also make NAAQS regulation of GHGs inappropriate or unworkable. States must “provide for the establishment and operation” of air quality monitoring devices. “This requirement has no relevance” to GHGs, which are well-mixed globally and have “no location-specific effect that could be measured by an air quality monitor.”

The NAAQS program gives states flexibility if they are downwind of polluting states, and may impose additional requirements on upwind states. Those so-called good neighbor provisions have no reasonable application to GHGs. Because GHG concentrations in the ambient air are essentially uniform across the globe, every state is simultaneously upwind and downwind with respect to all other jurisdictions worldwide.

To enforce compliance with NAAQS, the EPA may prohibit the Department of Transportation from awarding highway grants to noncompliant states, require new and modified sources in a noncompliant state to obtain two tons of emission reductions (“offsets”) for every ton they emit, and order the state to revise its SIP to include “all measures that can be feasibly implemented in the area.” CAA § 179(b)(1), (b)(2), (d)(2). Yet exercising those authorities would not bring any state into attainment with the proposed 350 ppm CO2 NAAQS. In such a context of nationwide and perpetual nonattainment, “the statutory devices that incentivize SIP submission and NAAQS attainment within specific geographic areas would serve no useful function.”

In short, if the EPA were to promulgate NAAQS for GHGs, the “cooperative federalism framework of the NAAQS regime would [eventually] collapse as ineffectual SIPs would give rise to ineffectual federal implementation plans (FIPs).” In the meantime, “states would be forced to play a meaningless regulatory charade with no hope of having any measurable effect on the GHG levels within their borders.” Wheeler thus declares: “EPA will not presume that Congress intended to legislate a meaningless exercise,” citing the Supreme Court’s dictum that “A purpose so wholly futile is not to be attributed to Congress.”

In conclusion, Wheeler advises petitioners to lobby Congress rather than demand that the EPA dictate climate policy through a 50-year-old provision neither designed nor intended for that purpose:

Congress has the power to craft a comprehensive solution to the problem of greenhouse emissions, but such a solution will necessarily involve equitable participation by other nations that emit significant amounts of GHG. EPA cannot create such a solution unilaterally and it has not been given the statutory tools that would be necessary.