EPA Proposes Plan for Addressing Regional Ozone Transport Under Clean Air Act

Legal Intelligencer

(By Varun Shekhar)

On April 6, the U.S. Environmental Protection Agency (EPA) published in the Federal Register a proposed rule that, if finalized, would establish a federal implementation plan (FIP) to address regional ozone transport under the Clean Air Act (CAA). The proposed rule is noteworthy based on the numerous adjustments it makes to existing nitrogen oxides (NOx) emissions budgets for a number of states, including Pennsylvania, as well as marking the first time that the EPA has used the regional ozone transport provision under the CAA to regulate sources other than electricity generating units (EGUs).


Section 109 of the CAA directs the EPA to establish federal National Ambient Air Quality Standards (NAAQS) for certain pollutants deemed appropriate by the EPA. One of these pollutants is ozone, which is formed in part by photochemical reactions involving NOx and volatile organic compounds (VOCs). The most recent NAAQS for ozone was promulgated by the EPA in 2015, which establishes an eight-hour 70 parts per billion ambient standard. Section 110 of the CAA also directs states to submit to the EPA “state implementation plans” (SIPs), to detail how emissions from facilities in each state will attain the NAAQS. SIPs are also required to demonstrate that emissions from facilities in the state will not “contribute significantly” to nonattainment or interfere with continued attainment of the NAAQS by other states (often referred as the CAA’s “Good Neighbor” provision). If a state fails to submit a satisfactory SIP to achieve these requirements, the EPA is required under the CAA to develop and implement a FIP for that state.

The EPA’s approach to implementing the CAA’s Good Neighbor provision began in 2011 with enactment of the Cross-State Air Pollution Rule (CSAPR) (76 Fed. Reg. 48208), designed to address the 1997 ozone NAAQS among other things. Under this rulemaking, the EPA established a NOx emission budget and trading system for EGUs. The emission budgets, developed on a state-by-state basis, were based on a four-step process involving: identification of receptors in downwind states with demonstrated issues achieving the ozone NAAQS; determining those upwind states contributing to downwind nonattainment through ambient air quality modeling; identifying and quantifying the amount of emissions that significantly contribute to downwind nonattainment and the amount of emissions reductions needed to prevent such downwind nonattainment; and development and implementation of an emission budget. Based on each state’s budget, affected EGUs in each state would be allocated one allowance per ton of NOx emissions, which would be debited from their account at the end of each ozone season. Those sources with a shortfall of NOx allowances would need to purchase additional allowances.

CSAPR and its periodic updatesincluding the “CSAPR II” rulemaking in 2016 (81 Fed. Reg. 74504) which was developed in response to the promulgation of the 2008 ozone NAAQShave been subject to litigation over the years. In particular, in Wisconsin v. EPA, 938 F.3d 303 (D.C. Cir. 2019), the U.S. Court of Appeals for the D.C. Circuit found that the emission budgets established by the EPA were not sufficient to fully eliminate upwind states’ significant contributions to downwind nonattainment, in violation of the CAA’s Good Neighbor provision. As a result, the EPA promulgated a subsequent revision to CSAPR and CSAPR II in April 2021 (86 Fed. Reg. 23054) to further reduce the emission budgets allocated to each state. The proposed rule implements further reductions to emission budgets, based on implementation of the 2015 ozone NAAQS which is more stringent than the 2008 ozone NAAQS.

Notable Features of the Proposed Rule

In the proposed rule, the EPA would continue to find that interstate transport of NOx emissions from EGUs in several states, including Pennsylvania, significantly contribute to downwind nonattainment of the 2015 ozone NAAQS. However, the proposed rule would expand the number of states subject to this finding and would also find that NOx emissions from certain non-EGU sources also are significant contributors to downwind nonattainment. Finally, the proposed rule would issue a FIP for these states, imposing a revised NOx emissions trading program among these states.

While the proposed FIP would not appreciably change the types of EGUs subject to the existing NOx trading program, it would, among other things, expand the trading program under the current iteration of CSAPR to include EGUs from eight other states. It would also reduce the amount of NOx emissions budgets for states by varying amounts between 2023-2025, and by roughly 25% beginning in 2026, reflecting an emissions level based on installation of post-combustion selective catalytic reduction (SCR) or noncatalytic reduction (SNCR) controls at 30% of coal-fired power plants. The proposed FIP’s NOx emissions trading program would also include a “recalibration” provision, such that a surplus of banked allowances among all sources in a state beyond a 10.5% target bank amount would be subject to downward adjustment.

Moreover, the proposed rule would establish additional emissions limits beyond a strict trading program for certain affected EGUs. Coal-fired EGUs with greater than 100 MW nameplate capacity would be subject to a daily emissions limit of 0.14 lbs NOx/MMBTU. If a facility exceeds this limit, it would be charged allowances at a penalty rate of three times the normal rate (i.e., three allowances surrendered per excess ton NOx emitted). In addition, the proposed rule establishes a 50-ton limit for NOx over the emissions level at 0.1 lbs NOx/MMBTU, for EGUs that are found to be responsible for contributing to a state’s exceedance of its “assurance level,” i.e., 121% of the state’s emissions budget. These limits have potentially significant implications for facilities with a seasonal operating pattern.

Finally, the proposed rule would establish NOx emissions limits for several types of industrial sources other than EGUs (including reciprocating internal combustion engines in pipeline transportation of natural gas, cement kilns, boilers and furnaces in iron and steel mills, glass furnaces, paper mills and other equipment for chemical, petroleum and coal product manufacturing). These limits would be established on a source category basis. However, sources in these categories would not be required to participate in the trading program established for EGUs. If finalized, this would mark the first iteration of CSAPR in which EPA would use the Good Neighbor provision of the CAA to establish emission limits for specific source categories.

Key Takeaways

The proposed rule not only represents increased stringency in the existing NOx emissions trading program among EGUs under the CSAPR, it also reflects a substantial expansion in the scope of industries regulated under the CAA’s Good Neighbor provision. Sources may want to consider whether the proposed rule will establish limitations that are more stringent than those arising under other provisions of the CAA (for example, the “new source performance standards” under Section 111, or “reasonably available control technology” standards developed by states under Section 182). It also remains to be seen whether future iterations of CSAPR rulemaking will further expand the types of sources covered by the rule.

The proposed rule will remain open for public comment under docket number EPA-HQ-OAR-2021-0668 until June 21, (which includes a 15-day extension granted by the EPA). Given the wide array of industries that may be affected by the proposed rule, it is expected that it will elicit a substantial number of comments from industry, nonprofit organizations, and state and local agencies.

Varun Shekhar is a senior associate in Babst, Calland, Clements and Zomnir’s environmental and transportation safety groups. His environmental practice focuses on compliance matters arising under the Clean Air Act and implementing regulations. Contact him at vshekhar@babstcalland.com.

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Reprinted with permission from the June 2, 2022 edition of The Legal Intelligencer© 2022 ALM Media Properties, LLC. All rights reserved.