Clean Air Interstate Rule (CAIR) Overview

The Clean Air Interstate Rule (CAIR) program is designed to reduce the amount of fine particulate matter and ozone that crosses state lines in the eastern United States. CAIR caps emissions of nitrogen oxides and sulfur dioxide and sets up a market for facilities to trade emissions credits.

DHEC implements the CAIR program in South Carolina by including CAIR permits in affected Title V permitted facilities and determining allocations of emissions allowances for those facilities.

Legal Disputes

On July 11, 2008, the U.S. Court of Appeals for the D.C. Circuit (Court of Appeals) vacated CAIR. Following petitions filed by parties in the litigation the Court of Appeals issued a subsequent opinion on December 23, 2008, wherein it remanded the CAIR to the U.S. Environmental Protection Agency (EPA) without vacatur.

CAIR is now in effect while EPA develops a replacement rule. South Carolina's CAIR regulations, at Regulation 61-62.96, went into effect on May 1, 2009, replacing the NOX SIP Call Program. DHEC implemented CAIR in South Carolina through a State Implementation Plan (SIP) .

On July 6, 2011, the US Environmental Protection Agency (EPA) finalized a rule that replaced CAIR, the Cross State Air Pollution Rule (CSAPR). But that rule, too, has been challenged.

On August 21, 2012, the U.S Court of Appeals for the DC Circuit issued a ruling vacating the CSAPR.

On June 24, 2013, the U.S. Supreme Court granted the EPA's petition asking the court to review the DC Circuit court's decision. For updates on this case, see EPA's CSAPR webpage .