COMPARATIVE-EVALUATION OF METHODS FOR ESTIMATING POTENTIAL HUMAN EXPOSURE TO OZONE - PHOTOCHEMICAL MODELING AND AMBIENT MONITORING

Photochemical modeling and ambient monitoring of ground-level ozone co ncentrations provide two alternative/complementary methods for calcula ting potential population exposure estimates, A comparative evaluation of these methods was undertaken over a study area comprised of the en tire state of New Jersey and neighboring parts of Delaware, Maryland P ennsylvania and New York. Kriging, a geostatistical interpolation tech nique, was used for the interpolation of hourly ozone data from 38 air quality monitoring stations operating within the study area, to deriv e concentration fields for the entire domain. The Urban Airshed Model (UAM-IV), a comprehensive photochemical grid-based model, was then use d to calculate the same concentrations from emissions and meteorology inputs. Concentration fields, thus developed, were linked with corresp onding population data to calculate potential population exposure esti mates to outdoor ozone (E-p,E-o). The adequacy of kriging as an interp olation technique was evaluated by comparing E-p,E-o estimates derived via photochemical UAM modeling with those calculated by using concent rations obtained from kriging UAM-calculated values at the locations o f the monitoring stations. In general, UAM was found to predict higher E-p,E-o compared to those derived by kriging observations. In order t o test the robustness of the interpolation methodology with respect to assumptions of statistical correlation, two different semivariogram m odels, spherical and exponential, were used for kriging. Application o f the different semivariograms yielded almost identical E-p,E-o patter ns.