EPA
EPA/TTN/EFIG
The U.S. Environmental Protection Agency (EPA) Clearinghouse for Inventories and Emission Factors (CHIEF) provides a mechanism of exchanging information on air pollution control matters between federal, state, and local agencies, private citizens, universities, contractors and foreign governments. The CHIEF maintains air pollution emission factors and criteria for six major pollutants (particulates (PM-10), SO2, CO, NOx, VOC, and lead) and toxic substances from stationary and mobile sources.