Abstract
Continuous air pollutants and meteorological data, which were monitored at offical stations in Kanto and Keihanshin regions from April in 1975 to March in 1977, were statistically analysed. The following conclusions were obtained.
1) The appearance frequencies of days under the closed meteorological condition were 41 and 44% of a year in Kanto and Keihanshin regions, respectively, which were both at rather higher levels by some 15% compared with the 26% of the average frequency of such days in the Kanto region for the past tan years.
2) Wind direction under closed meteorological condition in both regions showed the trend as follows:
(1) In the warm season (June to September), air pollutants were transfered to inland by a sea breeze which began to blow at about 9 a. m. and countered to seashore by a land breeze which began to blow at about 9 p.m.
(2) In the cold season (November to February), too, similar phenomena occurred, although sea and land breezes began to blow at 12 a.m. and 6 p.m. respectively.
3) SO2 concentrations under closed meteorological condition were higher through all seasons in both regions than those under open meteorological condition.
NO2 concentrations under closed meteorological condition were also higher through all seasons in Keihanshinregion and through autumn and winter in Kanto region than those under open meteorological conditions.
NO concentrations showed no significant difference between closed and open meteorological conditions in both regions.
