EPA approved the Gila River Indian Community's tribal implementation plan to regulate air quality within the exterior boundaries of the tribe's reservation.

EPA promulgated new source performance standards and emission guidelines for commercial and industrial solid waste incineration units.

EPA established NESHAPs required for industrial/commercial/institutional boilers and process heaters at major sources

EPA promulgated NESHAPs for industrial boilers and commercial and institutional boilers at area sources.

EPA promulgated new source performance standards and emission guidelines for sewage sludge incineration units located at wastewater treatment facilities.

EPA amended certain NESHAP regulations for the Maricopa County air quality department in Arizona and the Santa Barbara County air pollution control district in California.

EPA stayed the requirement for chemical manufacturing area sources to comply with the Title V permit program during reconsideration of certain NESHAP provisions.

EPA extended attainment of the 1997 eight-hour ozone NAAQS for the Baltimore moderate nonattainment area until June 15, 2011.

EPA finalized amendments to the NESHAPs for existing stationary spark ignition reciprocating internal combustion engines.