Source	Definition	Examples
Stationary:
Major	Emissions of 10 tons per year or more of any one air toxic, or 25 tons per year or more of any combination of air toxics	Utilities, refineries, steel manufacturers, chemical manufacturers
Area	Emissions of less than 10 tons per year of any one air toxic pollutant, or less than 25 tons per year of any combination of air toxics	Dry cleaners, gas stations, auto body refinishing paint shops, decorative chromium electroplating operations
Mobile:
On-road	Emissions from motorized vehicles normally operated on public roadways	Cars, buses, sport-utility vehicles, light- and heavy- duty trucks
Non-road	Emissions from a diverse collection of engines, equipment, vehicles, and vessels operated off public roads	Construction and agricultural equipment, personal watercraft, lawn and garden equipment