As a part of study of air pollution by automobiles, measurements of servcral pollutants have been made in the high-way Iikura road tunnel, the Hibiya crossing and the inside of a car driving around the central area of Tokyo in the summer of 1974. Concentrations of polynuclear aromatic hydrocarbons (PAH) in the areas mentioned above were significantly higher than the valul in the control area (Chiyoda-ku, Tokyo) and the average values in 9 central areas of Tokyo. For example, concentration of benzo (a) pyrene (BaP) was about two times higher in the crossing and about 9 times higher in the tunnel than those in both the control and central areas. Concentrations of the other PAH (pyrene, benz (a) anthracene, benzo (ghi)-perylene, bonzo (k) flouranthene) in the tunnel were 2.5 to 4.6 times higher than those in the crossing rood.
PAH concentrations in a car were highly elevated by traffic congestion. The BaP concentration in the car was 6.4 times higher when the car was driven on the congested Showa Street than when it was on the Uchibori Street.
PAH concentrations in the car rose also significantly up by opening the car windows; that is concentration of BaP was 8.6 times higher when the windows were opened 10 cm wide than they were 1 cm wide. BaP concentrations in the car as well as in the tunnel increased with the increase of carbon monoxide concentration. It was also found that 90 to 98% of PAH in the air of the road tunnel as well as the crossing road were in the suspended particulates smaller than 8μm in diameter, that is respirable dust.
Concentrations of heavy metals in the air decreased in the order of the tunnel, the crossing and control area. Lead concentration was 31 times higher in the tunnel and 7 times higher in the crossing than the value in the control area. Particle size distributions of Pb and Cd were similar to those of PAH, but the distributions of the other heavy metals, for example Ni, Fe, Mn, were different from those of PAH.
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