On October 29, EPA published a proposed revision to its Cross State Air Pollution Rule (CSAPR) Update in response to the remand of the rule by the D.C. Circuit. The CSAPR Update was promulgated under the Clean Air Act’s “Good Neighbor” provision, which requires states to ensure that pollution from sources within their borders does not significantly contribute to the ability of downwind states to attain or maintain the National Ambient Air Quality Standards (NAAQS). Under the Good Neighbor provision, if a State Implementation Plan (SIP) does not adequately address the interstate transport of pollutants, EPA must step in and issue its own rules through a Federal Implementation Plan (FIP). EPA issued the CSAPR Update in 2016, imposing FIPs on 22 states requiring ozone season NO_x reductions from electric generating units (EGUs) to address the 2008 ozone NAAQS. In the 2018 CSAPR Closeout, EPA determined that no further emission reductions were required for all but two of the states covered by the CSAPR Update.

Both the CSAPR Update and the CSAPR Closeout were challenged in the D.C. Circuit by downwind states claiming that emission reductions required under those rules would not sufficiently address the upwind states’ Good Neighbor obligations under the 2008 ozone NAAQS. The D.C. Circuit remanded the CSAPR Update because it unlawfully allowed upwind states to continue their significant contributions to downwind air quality problems beyond the 2021 attainment deadline for the 2008 ozone standard and later vacated the CSAPR Closeout on the same grounds.

EPA’s proposed revision to the CSAPR Update addresses the remand of the CSAPR Update and vacatur of the CSAPR Closeout by focusing on the 2021 attainment deadline for the 2008 ozone standard. For the 22 states affected by the CSAPR Update and CSAPR Closeout, EPA has proposed the following:

• For nine of those states (Alabama, Arkansas, Iowa, Kansas, Mississippi, Missouri, Oklahoma, Texas, and Wisconsin), EPA found that existing CSAPR Update FIPs fully address their interstate ozone transport obligations for the 2008 ozone NAAQS.
• For 11 of those states (Illinois, Indiana, Louisiana, Maryland, Michigan, New Jersey, New York, Ohio, Pennsylvania, Virginia, and West Virginia), EPA determined that further ozone season NOx reductions are necessary and has proposed new FIPs for these states.
• For the remaining state, Kentucky, EPA has proposed to reverse a 2018 approval of the state’s “Good Neighbor” SIP and to require additional emission reductions.

EPA’s proposed revisions to the CSAPR Update are based on emission reductions at EGUs from optimization of existing Selective Catalytic Reduction (SCR) NO_x controls and installation of combustion controls, such as low NO_x burners and overfire air. EPA has not proposed reductions from non-EGU sources, finding that sufficient reductions could not be achieved at those sources before controls on EGUs have already accomplished the necessary emission reductions. However, EPA requests comment in the proposal on the potential for emission reductions from certain industry sectors and source types, including glass and cement manufacturing, industrial, commercial, and institutional boilers, and reciprocating internal combustion engines.

Public comments are due on the rule by December 14, 2020. EPA is under a court order to publish a final rule by March 15, 2021.