All national emission standards for hazardous air pollutants (NESHAP) or maximum achievable control technology (MACT) standards were promulgated after 1992. Pre-existing sources still must comply with the applicable industry standard, but under an extended deadline, as long as they have not reconstructed. An extended compliance date is listed in each maximum achievable control technology (MACT). In setting the standards, the Environmental Protection Agency (EPA) is allowed to distinguish between new and existing sources and to subject new or reconstructed major sources to stricter controls.
"Reconstructed" means replacement of component parts of a stationary source to the extent that the capital cost of the new components exceeds 50 percent of the capital cost to construct a comparable new source if it is technologically and economically feasible for the reconstructed source to meet the maximum achievable control technology (MACT) standard.