Best available control technology (BACT) is a standard established under the U.S. Clean Air Act (CAA) that requires regulated activities to incorporate the use of currently available technology to reduce their emissions of criteria pollutants (i.e., particulate matter, carbon monoxide, nitrogen oxides, sulfur oxides, and volatile organic compounds) to the maximum degree possible while taking into consideration economic, energy, environmental and other related costs. Under the U.S. federal New Source Review (NSR) program, BACT applies to construction of major new sources and major modifications (including relocation) of existing facilities within areas that meet U.S. Environmental Protection Agency (EPA) ambient air quality standards.

For the purposes of the NSR program, a major project is defined as one that has the potential to significantly increase emissions of pollutants, ...