Driver exposure to particulate matter in bangkok

The aims of this study were to determine the particulate matter with aerodynamic diameters ≥2.5 μm (PM_2.5) and 2.5–10 μm (PM_10–2.5) exposure levels of drivers and to analyze the proportion of elemental carbon (EC) and organic carbon (OC) in PM_2.5 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 PM_2.5 exposure level of the Tuk-tuk drivers was 86 μg/m³ in August and 198 μg/m³ in January. The mean for the non-air-conditioned bus drivers was 63 μg/m³ in August and 125 μg/m³ in January. The PM_2.5 and PM_10–2.5 exposure levels of the drivers in January were approximately twice as high as those in August. The proportion of total carbon (TC) in PM_2.5 to the PM_2.5 level in August (0.97 ± 0.28 μg/m³) was higher than in January (0.65 ± 0.13 μg/m³). The proportion of OC in the TC of the PM_2.5 in August (0.51 ± 0.08 μg/m³) was similar to that in January (0.65 ± 0.07 μg/m³). The TC exposure by PM_2.5 in January (81 ± 30 μg/m³) remained higher than in August (56 ± 21 μg/m³). The mean level of OC in the PM_2.5 was 29 ± 13 μg/m³ in August and 50 ± 24 μg/m³ in January. In conclusion, the PM exposurelevel in Bangkok drivers was higher than that in the general environment, which was already high, and it varied with the seasonsand vehicle type. This study also demonstrated that the major component of the PM was carbon, likely derived from vehicles.