air quality assessment & management
Reference and User Manual
VOC SpeciationEmissions of VOCs is usually from distributed, area sources rather than stacks, and due to evaporation rather than combustion processes as well as from biological processes.
Fugitive VOC emisisons originate from industrial and commercial areas and households (e.g., from chemical production processes, use of points and solvents), and the transportation (fuel) system.
Since the simulation models require more detailed emission data (in terms of chemical substances or "species") than are realistically measured, assumptions on the distribution of bulk data (VOC) are made referred to as speciation.
For the 3D dynamic photochemical model CAMx, AirWare uses the EPA speciation list (http://www.epa.gov/ttn/chief/emch/speciation/cbiv-profiles_mar_4_2002.xls ) to create CBIV lumped species from TOG (total organix gases) taken from: http://www.epa.gov/ttn/chief/emch/speciation/
TOG = factor*VOC (default: factor=1); values above one represent the Methane fraction.
The mass speciation factors for TOG are defined in the
default profile (#0) which can be overloaded by emission source class, type, and individual source. (Source: http://www.epa.gov/ttn/chief/emch/speciation/)