Abstract
Estimation of the long-term average concentration in a comparatively wide region into which substances are continuously discharged should be required in the environmental assessment of chemical substances. A model with which to estimate long-term average atmospheric concentrations of chemicals was developed. The model validation was conducted for trichloroethylene and tetrachloroethylene concentrations in atmosphere by comparing calculated values and observed values from a monitoring survey conducted over several weeks in summer and winter in the Kanto region. Good agreement with the measured values was obtained for the monthly average concentration of trichloroethylene, excluding two sites for the winter measurements where the monitored values were extremely high. For tetrachloroethylene, the calculated values greatly overstimated the monitored values at urban sites. More accurate emission date will improve model performance, because extremely high calculated values were mainly influenced by the methodology used to estimate the gridded source inventory. The model is capable of estimating the long-term (such as monthly) average distribution of concentration of chemicals in a wide flat area such as the Kanto plain.
