On May 13, 2010, EPA issued its GHG Tailoring Rule, which will require hundreds of stationary source facilities to address, and thus reduce, GHG emissions under the Clean Air Act's New Source Review, Prevention of Significant Deterioration (PSD), and Title V Operating Permit programs. Through this rule, EPA has attempted to rewrite the Clean Air Act's requirement that any facility emitting more than 250 tons per year of a pollutant must obtain a permit. Arguing that this low threshold is "not appropriate" or feasible for GHGs, EPA raised it to 75,000 and 100,000 tons per year ("tpy"). By doing this, it limited the applicability of the new rule for GHGs to large facilities. EPA estimates that in the first two years about 550 new sources will require permits and it will need to issue permits to 900 other new and modified emission sources because of increased GHG emissions.

Beginning in July 2011, EPA will require all new facilities with GHG emissions of at least 100,000 tpy — and modifications at existing facilities that would increase GHG emissions by at least 75,000 tpy — to be permitted. Those permits must demonstrate the use of the best available control technologies (BACT) to minimize GHG emission increases when facilities are constructed or significantly modified. EPA also made clear that while it is starting at 75,000 tpy, it plans to ratchet that down in ensuing years requiring even small emitters to obtain permits. Next year EPA plans to begin another rule-making process to phase in more permits and determine whether some smaller sources of emissions can be excluded permanently from the process.