2002 Volume 37 Issue 2 Pages 131-140
The atmospheric concentrations of six polycyclic aromatic hydrocarbons (PAHs) whose carcinogenic activities have been shown by the WHO and determination method shown by U.S.EPA were measured. The PAHs were collected for 24 hours at three sites of a large intersection, a residential area and a mountain area. Temporal variation of the PAHs concentrations and composition ratios of the PAHs were analysed.
The PAHs concentrations in air at the intersection and the residential area were varied between 8-20 fold and 20-50 fold in a week, respectively, and 60-90 fold in a year. Therefore, the mean exposure concentration to residents can not be grasped correctly by measurements for several times a year. The concentrations in winter were higher than those in summer, but the composition ratios of 6PAHs were almost constant, and the concentrations were BbF≥IcdP>BaP≥BaA≥BkF>>DahA in any terms. Hence, it was found that the grade of the relative degradation of each PAH in the ambient air doesn't change greatly through the year.
In comparison with the concentrations in the intersection, the concentrations in the residential area were about 1/2-1/4 and the concentrations in the mountain area were about 1/8-1/30. So it was shown that the PAHs from various emission sources spread extensively. Moreover, in comparison among the composition ratios in these three sites, it was suggested that BaA degraded more easily than the other PAHs in the ambient air.
Carcinogenic risks by 6PAHs were estimated in the order of BaP>>DahA>IcdP≅BbF>BaA>>BkF, and the risk of BaP was especially high. Moreover, it was revealed that the risks by 6PAHs were over 5×10-5 in the intersection and the residential area and the risk may be near 1×10-5 even in the mountain area.
Consequently, the results of this study showed that efficient monitoring was necessary immediately to set environmental standards of PAHs and to regulate various emission sources.
