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ensure accuracy. Air Quality Management in the United States
Each of those components is described below. The first step in
developing an emission-control strategy for a criteria pollutant
is to develop an inventory of pollutant emissions that lists all
sources of the pollutant or its precursor and the rate at which
each source emits the pollutant to the atmosphere. EPA has
specified a general procedure for emissions-inventory
development that categorizes emissions into four source types:
stationary, mobile, biogenic, and geogenic (EPA 2003f).
Stationary sources are further divided into major stationary and
area sources. Major stationary sources are defined as stationary
sources having emissions that exceed a minimum or threshold
level, which varies depending on the pollutant. Stationary
sources that fall below the threshold leve