Analysis and comparative evaluation of AIRPOL-4.

Data are present which establish the utility and integrity of an air pollution prediction model, AIRPOL-4, relative to CALAIR (developed by the California Department of Highways) and HIWAY (developed by the U.S. Environmental Protection Agency). The three models are compared with regard to the basic formulation, the determination of stability classes and dispersion parameters, carbon monoxide (CO) level versus wind spend relationship, and ability to determine emission factors and analysis upwind receptors. The cost performances of the models and their predictive performances relative to observed field data are described. Both absolute and relative measures of the performances of each of these models are described. AIRPOL-4 costs less and is simpler to use, is significantly more accurate, and can accurately determine OC levels for both the upwind and downwind sides of roadways. AIRPOL-4 yields accurate predictions for a wide variety of meteorological conditions, including small road/wind angles and very low wind speeds, and accurate carbon monoxide predictions for a wide variety of topogrographies and source/receptor geometrics.