An ASPEN (Assessment System for Population Exposure Nationwide) model: is a computer simulation model used to estimate toxic air pollutant concentrations. The ASPEN model takes into account important determinants of pollutant concentrations, such as: rate of release, location of release, the height from which the pollutants are released, wind speeds and directions from the meteorological stations nearest to the release, breakdown of the pollutants in the atmosphere after being released (i.e., reactive decay), settling of pollutants out of the atmosphere (i.e., deposition), and transformation of one pollutant into another (i.e., secondary formation). The model estimates toxic air pollutant concentrations for every census tract in the continental United States, Puerto Rico and the Virgin Islands. However, the output for the model is presented at the county level. For more detailed information, see ASPEN Model.

Related Articles

Hazardous Air Pollutant Exposure Model ■■■■■■■■■
Hazardous Air Pollutant Exposure Model : The Hazardous Air Pollutant Exposure Model, Version 4 (HAPEM4) . . . Read More
Dispersion model: ■■■■■■■
A Dispersion model: is a computerized set of mathematical equations that uses emissions and meteorological . . . Read More
Nuclear energy ■■■■■■
A nuclear energy is Energy or power produced by nuclear reactions (fusion or fission). Other /More definition: . . . Read More
Aerodynamics ■■■■■■
Aerodynamics in the environmental context refers to the study of how air moves around objects, including . . . Read More
Background concentrations: ■■■■■■
A Background concentrations: is In this context, EPA uses background concentrations to mean the contributions . . . Read More
Primary NAAQS ■■■■■■
Primary NAAQS: Primary National Ambient Air Quality Standards (NAAQS) in the environmental context refer . . . Read More
Chimney ■■■■■
In the environmental context, a chimney refers to a structure that provides ventilation for smoke or . . . Read More
Power plant ■■■■■
A Power plants is a facility (plant) that produce energy. In the context of the environment, "power plants" . . . Read More
Deposition ■■■■■
A deposition is the processes by which chemical constituents move from the atmosphere to the earth's . . . Read More
Droplet ■■■■■
Droplet in the environmental context typically refers to a small particle of liquid, often water, that . . . Read More