Atmospheric photochemistry of O3-NOX-RH were considered theoretically, to clarify the reasons for the different trends of between the formation of photochemical oxidants (OX) and its primary pollutants for the Low- and High-NOX regimes. Equations of OH, HO2, and production of ozone (O3) as a function of nitrogen oxides (NOX) and reactive hydrocarbons (RH) were represented in this study. For the Low-NOX regime, HO2 radical is proportional to RH but independent of NOX. OH radical is proportional to NOX but inversely-proportional to RH. O3 production is proportional to NOX but has a weak dependence on RH. For the High-NOX regime, OH and HO2 radicals concentrations and O3 production are proportional to RH but inversely-proportional to NOX. In addition, the Osaka Bay and surrounding areas of Japan were evaluated with the mass balance of odd-hydrogen radicals (Odd-H) using CBM-Ⅳ photochemical mechanism, in order to distinguish the Low- and High-NOX regimes. The Harima area (emission ratio, RH/NOX = 6.1) was classified to the Low-NOX regime. The Hanshin area (RH/NOX = 3.5) and Osaka area (RH/NOX = 4.3) were classified to the High-NOX regime.

We developed a numerical model that considered the influences on the thermal environment of vegetation, water surfaces and buildings to predict micro climatic changes in a few km2 scales; and applied this model to the Mino residential development region in Osaka Prefecture by using a nested technique. The calculated temperatures and winds in the residential development region reasonably agreed with the observed ones. We then investigated the influences on the thermal environment of the construction of a dam, the change of the green coverage rate. The results obtained from the numerical simulations were qualitatively reasonable.