inventory terminology, emissions are grouped as point (major), area, and
mobile sources. The following
definitions describe how these terms are used in the emission inventory.
|Major sources: Pollutants
can be released when equipment leaks, when material is transferred from one
area to another, or when waste is given off from a facility through smoke
|Area sources: Examples
include neighborhood dry cleaners, small metal plating operations, gas
stations, and woodstoves. These sources may not be identified in the
inventory by a specific location.
Routine releases, such as those from industry, cars, landfills, or
incinerators, may follow regular patterns and happen continuously over
time. Other releases may be routine
but intermittent, such as when a plant's production is performed in
batches. Accidental releases can occur
during an explosion, equipment failure, or a transportation accident. The timing and amount released during
accidental releases are difficult to estimate.