Interstate Air Transport of Pollutants

Cross-State Air Pollution Rule (CSAPR)

The Cross-State Air Pollution Rule (CSAPR) was published in the Federal Register on August 8, 2011 (76 FR 48208), and subsequently amended on June 12, 2012 (77 FR 34830), December 3, 2014 (79 FR 71663), and October 26, 2016 (81 FR 74504). In the eastern half of the U.S., the CSAPR addresses air pollution from upwind states that crosses state lines, affecting air quality in downwind states. Sulfur dioxide (SO2) and nitrogen oxides (NOX) emissions react in the atmosphere, which contribute to the formation of fine particle (soot) and ground-level ozone (smog) pollution in downwind states. The CSAPR requires fossil fuel-fired electric generating units (EGUs) at coal-, gas-, and oil-fired facilities to reduce emissions to help downwind areas attain fine particle and/or ozone National Ambient Air Quality Standards (NAAQS).

The CSAPR Update rule, published October 26, 2016 (81 FR 74504), updated the CSAPR rule to address the summertime (May though September) interstate transport of ozone with respect to the 2008 ozone NAAQS. South Carolina was found to not contribute significantly to ozone air quality problems in downwind states and was removed from the CSAPR for the ozone season.

On August 25, 2017, the Department added Regulation 61-62.97, Cross-State Air Pollution Rule (CSAPR) Trading Program, to incorporate the EPA’s CSAPR trading program for South Carolina in 40 CFR Part 97 for annual levels of NOX and SO2, to address mandatory transport and regional haze state implementation plan (SIP) infrastructure elements. The EGUs in the CSAPR program are subject to both the NOX Annual and SO2 programs.

Nitrogen Oxides (NOX) SIP Call Regulations

On January 25, 2019, the Department amended Regulation 61-62.96, Nitrogen Oxides (NOX) Budget Program, to repeal the Clean Air Interstate Rule (CAIR) trading program regulations (Subparts AA-IIII), after the repeal of the federal CAIR regulations. The Department reinstated applicable portions of the NOX SIP Call regulations (Subparts A-I) to maintain state compliance with federal NOX SIP Call requirements, addressing summertime ozone-season interstate transport. Sources subject to the NOX SIP Call include EGUs and large non-EGUs.

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Marie F. Brown, (803) 898-1796