Driver exposure to particulate matter in Bangkok

The aims of this study were to determine the particulate matter with aerodynamic diameters >= 2.5 mu m (PM2.5) and 2.5-10 mu m (PM10-2.5) exposure levels of drivers and to analyze the proportion of elemental carbon (EC) and organic carbon (OC) in PM2.5 in Bangkok, Thailand. Four bus routes were selected. Measurements were conducted over 10 days in August (rainy season) 2008 and 8 days in January (dry season) 2009. The mean PM2.5 exposure level of the Tuk-tuk drivers was 86 mu g/m(3) in August and 198 mu g/m(3) in January. The mean for the non-air-conditioned bus drivers was 63 mu g/m(3) in August and 125 mu g/m(3) in January. The PM2.5 and PM10-2.5 exposure levels of the drivers in January were approximately twice as high as those in August. The proportion of total carbon (TC) in PM2.5 to the PM2.5 level in August (0.97 +/- 0.28 mu g/m(3)) was higher than in January (0.65 +/- 0.13 mu g/m(3)). The proportion of OC in the TC of the PM2.5 in August (0.51 +/- 0.08 mu g/m(3)) was similar to that in January (0.65 +/- 0.07 mu g/m(3)). The TC exposure by PM2.5 in January (81 +/- 30 mu g/m(3)) remained higher than in August (56 +/- 21 mu g/m(3)). The mean level of OC in the PM2.5 was 29 +/- 13 mu g/m(3) in August and 50 +/- 24 mu g/m(3) in January. In conclusion, the PM exposure level in Bangkok drivers was higher than that in the general environment, which was already high, and it varied with the seasons and vehicle type. This study also demonstrated that the major component of the PM was carbon, likely derived from vehicles. Implications: Exposure to fine particulate matter (PM2.5) in public transportation vehicles could have harmful health effects on both drivers and commuters in Bangkok, Thailand, where air pollution from vehicle exhaust is a serious problem. Exposure to fine particulate matter within moving vehicles has not been sufficiently investigated. Thus, the authors measured the levels of PM2.5 within various types of transportation vehicles in Bangkok. The results are the first to demonstrate that drivers and commuters in Bangkok are exposed to a high level of PM2.5, which cannot be detected by current roadside monitoring, and suggest the need for further pollution control measures.