2020 Volume 55 Issue 2 Pages 78-91
A trend analysis of Hazardous Air Pollutants (HAPs) concentrations (21 substances) in Japan during the period from 2001 to 2015 was conducted to investigate temporal variations using monitoring data from the Ministry of the Environment of Japan. The monitoring sites were classified into three categories, i.e., general environment (I), stationary industrial region (H), and road site (E) for all over Japan and 6 regions in Japan. Most of the HAPs concentrations tended to decrease except for several species. The trend analytical value, which is described as [concentrations], was below the environmental standard or guideline values. Except for several species, the total reductions of the [concentrations] were 13‒79% for I, 19‒62% for H, 19‒74% for E. In I, the seasonal variation was categorized as three types; i.e., higher values in the winter/spring seasons resulting from the high contributions of transboundary transport from Northeast Asia, higher values in the summer due to a higher contribution from domestic sources, and the mixed type. The difference in the [concentrations] among the region was greater in the first half of the 2000s and these differences began to decrease in the 2010s. The [Concentrations] of the HAPs in H and E were 1‒3 and 0.9‒1.5 times greater than those in I, respectively.
