Estimated pollutant concentrations beyond 80 km from a coal power plant stack

Concentrations of criteria pollutants, i.e. SO2, NO2, TSP, and PM10 were estimated at various downwind distances from the stack. The distances ranged from 1 to 10 km (at 1 km intervals), and 11 to 80 km (at 5 km intervals). This modeling was limited to 50 km, and then to 80 km, as an upper bound of reasonable results using the Environmental Protection Agency's approved Industrial Source Complex-Long Term (EPA ISCLT) model. Ambient concentrations at distances greater than 80 km from the stack were desired at a number of selected points, i.e., 99.2, 112, 160, 240, 320, 560, 800, and 1600 km. These concentrations are used in the subsequent health impact analysis as part of the U.S.-EC fuel cycle study. The initial prediction was performed using an emission value of 1 g per second (g/s). Ambient concentrations for SO2, NO2, TSP, and PM10 resulting from the coal-fired power plant emissions were then estimated by multiplying the concentrations derived by the corresponding emission rates in g/s. The emission rate values used are shown. Seasonal and annual average concentrations were computed for distances ranging from 1 to 8 km from the stack for 16 sectors on a polar grid with a 22.5' of angular increment. The spatial and temporal resolutions in the analyses were limited to the 16 directions and 4 seasons, respectively. Since the health impact analysis does not require air quality data on a seasonal basis and the yearly average concentrations appear to be adequate, the annual averages were used. ISCLT computed the annual average as the arithmetic average of the four seasonal averages