Region 1: EPA New England
How are these Emission Estimates Prepared?
The emission estimates are prepared using a variety of means. Emissions estimates for point sources are primarily obtained from annual information collection requests sent by the state air pollution agency to the large industrial sources within their borders. Area source emission estimates are most often prepared by the state air agencies themselves via use of indicators of activity levels such as gasoline consumption levels, solvent use, and population data, in conjunction with emission factors developed by EPA. Mobile source emission estimates are also prepared primarily by state air agencies using models provided by EPA that use data such as vehicle miles traveled, fuel characteristics, and equipment populations to approximate emissions over broad geographic areas, such as a county. EPA emission estimates are used to gap fill parts of the emissions inventory that a state air agency does not provide estimates for.