On May 13, 2010, EPA finalized its “tailoring” rule  aimed at focusing new source review and Title V permitting requirements on the largest stationary sources. The need for this proposal results from interlocking provisions contained in the Clean Air Act. Under the constructs of the Act, any pollutant subject to regulation under any provision of the Act triggers additional requirements including:
EPA issued its first standards for greenhouse gass (GHG) emissions on April 1, 2010, when it finalized rules setting GHG standards for light-duty vehicles.
The tailoring rule is EPA’s effort to modify the current thresholds in the Act – new sources emitting 100-250 tons per year of greenhouse gases would be subject to these requirements. The final rule raised this threshold and phases-in these requirements. Beginning on January 2, 2011, sources currently subject to new source review permitting requirements for other pollutants would also have to meet requirements for greenhouse gas emissions if their GHG emissions exceeded 75,000 tons per year. Beginning on July 1, 2011, these requirements would also apply to any new sources with GHG emissions greater than 100,000 tons per year regardless of the amount of emissions of other pollutants they emit.