ANALYSIS OF WINTERTIME NO2 POLLUTION IN THE TOKYO METROPOLITAN-AREA

The high concentration of NO2 in the Tokyo Metropolitan area was inves tigated by means of air quality monitoring station data analysis and t wo numerical models: a photochemical box model and a photochemical gri d model. Based on monitoring data, the typical variation with time of NO, NO2 and O-3 for days with high NO2 concentrations is presented. Th e application of the photochemical box and photochemical grid models s uccessfully reproduced these variations when using typical emission in tensities for NOx and NMHC from the Tokyo downtown area. Model results revealed that the high concentrations of NO2 in winter (exceeding the Japan environmental quality standard) mainly result from photochemica l oxidation of NO to NO2.