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Definitions
Point Sources
The major point source emissions
categories are power plants, industrial boilers, petroleum refineries,
industrial surface coatings and chemical manufacturing industries. Point
sources' emissions are generated from stack emissions. Since most of the
records are kept in AIRS/AFS, the point sources information is readily
available for developing a control strategies, tracking and implementation
of the State Implementation Plans (SIP). For SIP inventory purposes, the
point source emission cutoff is 10 tons per year for VOC and 100 tons per
year for NOx and CO sources. For VOC sources emitting 10 tons per year
or more, base year inventory emissions must be determined from each facility.
Area Sources
Area sources are those emissions
that are too small to be treated as point sources. Area sources' emissions
can be generated from solvents used for surface coating operation, degreasing,
graphic arts, dry cleaning and gasoline station (tank truck unloading and
refueling). Area sources are the activities where aggregated source emissions
information is maintained for the entire source categories instead of each
point source, and are reported at the county level.
Mobile Sources
Mobile sources are categorized
for highway and off-highway sources. The highway sources include the automobile,
buses truck and other vehicle traveling on local and highway roads. The
emission from highway vehicles represents one third of the overall national
volatile organic compounds (VOC) and 40 percent of the overall nitric oxide
(NOx) emissions. Highway emissions are calculated using MOBILE models.
States must present highway mobile source emissions by pollutant (VOC,
NOx and CO) and by individual nonattainment county. Off-highway sources
are any mobile combustion sources such as railroads, marine vessel, off-road
motorcycle, snowmobiles, farm, construction, industrial and lawn/garden
equipment. Emissions are determined based on a source activity variable.
Activity levels for each off-highway category must be developed using EPA
guidance documents.
Actual Emissions
The annual "actual"
emissions which have been estimated or calculated for a plant in the
State Emission Inventory, added to those annual emissions that have been
removed by the application of a control factor.
Allowable Emissions
Maximum emissions for a pollutant
that a plant or a source is allowed to discharge into the atmosphere legally.
Potential Controlled
Emissions
Pollutant emissions while operating
at the maximum design capacity, a schedule of 8760 hours per year and considering
the efficiency of the pollution control equipment.
Potential Uncontrolled
Emissions
Pollutant emissions while operating
at the maximum design capacity and a schedule of 8760 hours per year.