城市公交流动微环境中苯系物污染现状及致癌风险评价

Pollution condition and cancer risk of BTEX in mobile microenvironment of urban public transportation vehicles

通过监测杭州市公交中不同类型公交车、出租车流动微环境内的苯系物(BTEX)浓度,对杭州市公共交通流动微环境中的BTEX的致癌风险进行了评估。结果表明,杭州市公交流动微环境中的BTEX均值为72.36μg/m3,其中苯、甲苯、乙苯、二甲苯均值分别为15.47、23.52、6.11、17.78μg/m3。公交车流动微环境中的苯浓度低于出租车流动微环境中的。杭州市公交流动微环境中BTEX中的苯、甲苯、乙苯、二甲苯体积比约为3∶4∶1∶3,接近汽车尾气中这4者的相应比,交通工具类型、所用的动力、通风状况等对公交流动微环境中的BTEX浓度均有不同程度的影响。杭州市公交流动微环境中BTEX对不同人群的致癌风险为1.26×10-6～5.92×10-6,超过了美国环境保护署(EPA)制定的致癌风险限值。相对来说,乘坐出租车的致癌风险是乘坐公交车的1.35倍。

The concentration of benzene, toluene, ethylbenzene and xylene （BTEX） in the carriages of buses and taxis in Hangzhou was measured to investigate the pollution condition and cancer risk of BTEX in public transportation vehicles in Hangzhou. Results showed that the average BTEX concentration in public transportation vehicles of Hangzhou was 72.36 g/m^3 with the concentration of benzene, toluene, ethylbenzene and xylene were 15.47, 23.52, 6.11, 17.78 g/m^3 respectively, and the average benzene concentration in buses was lower than that in taxis. The volume ratio of benzene, toluene, ethylbenzene and xylene in mobile microenvironment was 3 ： 4 ： 1 ： 3, which was closer to the ratio that in automobile exhaust. Concentration of BTEX in mobile microenvironment was seriously influenced by types, motivities, and ventilation of vehicles. The cancer risk of BTEX in vehicles carriages was ranged from 1.26×10^-6 to 5.92×10^-6, exceeding the limit level of cancer risk suggested by EPA. The cancer risk caused by BETX pollution in taxis was 1.35 times than that in buses.