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).

Background

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.