Relation between heat islands and NO2 pollution in some Japanese cities

Abstract

In Japanese urban areas, NO_x air pollution has recently become more and more serious, and a rise in atmospheric temperature has been observed. This correlation was surveyed in 187 locations, where NO₂ concentration monitoring and atmospheric temperature measurement were conducted simultaneously and separately during the same period from 1982 to 1988. The following results were obtained. First, the percentage of areas where NO₂ concentration increased was 72%. Second, the percentage of areas where the correlation coefficient between the annual mean NO₂ concentration and the elapsed years was larger than 0.20, and at the same time the correlaltion coefficient between the annual mean NO₂ concentration and the annual mean atmospheric temperature was larger than 0.20, was 23%. About three-quarters of these areas were in the Tokyo and Osaka megalopolis. Third, in these areas, the relation between the mean NO₂ concentration and the regression coefficient of the change in atmospheric temperature relative to the change of annual mean NO₂ concentration was suspected to be distributed steeply with a reflected point in NO₂ concentration.