"The Commuters�f Exposure to Volatile Chemicals and Carcinogenic Risk in Mexico City" 

Naohide Shinohara¹, Adrian A. Fernandez-Bremauntz², Salvador Blanco Jimenez², Yukio Yanagisawa³

¹National Institute of Advanced Industrial Science and Technology
²Mexico's Instituto Nacional de Ecologia
³The University of Tokyo

ATMOSPHERIC ENVIRONMENT, Vol.39 No.19 pp.3481-3489 (2005)

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Abstract

The commuters�f exposure levels to volatile organic compounds were investigated in the following public transport modes: private car, microbus, bus, and metro along three commuting routes in the Metropolitan Area of Mexico City. The target chemicals were benzene, toluene, ethylbenzene, m/p-xylene, and formaldehyde. Integrated samples were taken while traveling during the morning rush hour (weekdays 7:00 a.m. to 9:00 a.m.) for consecutive 6 weeks in June and July in 2002. Scheffe test showed that the average concentrations of all chemicals inside cars and microbuses were statistically higher than in metro trains (P<0.05). For non-formaldehyde chemicals, the average levels inside automobiles were significantly higher than in metro trains and buses (P<0.05). The exposure level of formaldehyde in the microbus was much higher than those in the car, bus, and metro (P<0.05). On the other hand, there were no differences in the exposure levels among transport routes. These findings suggest that for commuting trips of comparable durations, car and microbus passengers are exposed to higher levels of volatile organic compounds than bus and metro commuters. These findings are consistent with previous studies looking at exposure of commuters to carbon monoxide. The lifetime carcinogenic risk due to commuting by car was 2.0�~10-5-3.1�~10-5, that by microbus was 3.1�~10-5-4.0�~10-5, that by bus was 2.0�~10-5-2.7�~10-5, and that by metro was 1.3�~10-5-1.7�~10-5 in Mexico City. 

Keywords

Personal exposure, Commuting, Benzene, Formaldehyde, Lifetime cancer risk, Potential carcinogenic incidences