On June 14, 1999, under the authority of section 112 of the Clean Air Act (CAA), EPA promulgated national emission standards for hazardous air pollutants (NESHAP) for new and existing sources in the Portland cement manufacturing industry. On December 15, 2000, the United States Court of Appeals for the District of Columbia Circuit (D.C. Circuit) remanded parts of the NESHAP for the Portland cement manufacturing industry to EPA to consider, among other things, setting standards based on the performance of the maximum achievable control technology (MACT) floor standards for hydrogen chloride (HCl), mercury, and total hydrocarbons (THC), and metal hazardous air pollutants (HAP). EPA published a proposed response to the court's remand on December 2, 2005. We received over 1700 comments on the proposed response. This action promulgates EPA's final rule amendments in response to the court's remand and the comments received on the proposed amendments.