The ambient air concentrations of PM10 were observed in Bangkok and its vicinity areas including Nonthaburi and Nakhon Pathom, Thailand. The selected study areas are located near heavy-traffic roads with a high concentration of traffic-related air pollution. The ambient air samples were collected in the winter season (October 2019 to February 2020). The highest average level of PM10 was found in Nonthaburi (66.63 µg/m³), followed by Bangkok (56.79 µg/m³) and Nakhon Pathom (40.18 µg/m³), respectively. The morphology of these particles is typically spherical and irregular shape particles. At the sampling site in Bangkok, these particles are primarily composed of C, O, and Si, and a certain amount of metals such as Fe, Cu, and Cr. Some trace amount of other elements such as Ca, Na, and S are present in minor concentration. The particles collected from Nakhon Pathom and Nonthaburi sampling sites contain the main abundant elements C, O, and Si, followed by Cu, Cr, S, Fe, Ca, and Na, respectively. These particles are an agglomeration of carbon particles resulting from the incomplete combustion of organic matter. Their origin may be associated with road dust, vehicle emission, and the erosion of building products. It can be noted that the levels and characteristics of PM10 are key factors in understanding the behavior of the particles in not only atmospheric visibility but also human health risks.

Concentrations of PM₁₀, PM_2.5, and the BTEX chemical group were studied in Nakhon Pathom, Thailand. The occupational health risk for workers (security guards and printing machine operators) was estimated against exposure to these pollutants. The average levels of PM₁₀, PM_2.5, and BTEX (benzene, toluene, ethylbenzene, and xylenes) were 67.32, 40.21, and 80.93 µg/m³, respectively. Among the BTEX group, toluene was the most prevalent at all the sampling sites, with mean levels of 55.71 µg/m³. The measured toluene/benzene ratios (T/B) indicated that the potential sources of BTEX at EG, CP1, and CP2 sites were influenced by vehicular or traffic sources. The level of benzene was utilized for evaluating the risk of cancer, whereas toluene and PM_2.5 were estimated for non-cancer health risk. According to the health risk assessment (at the 95% CI), security guards tended to have higher cancer risk values due to benzene (4.04 × 10⁻⁵) when compared to printing machine operators (2.41 × 10⁻⁵) due to their frequent exposure to particular sources of high concentration. Meanwhile, the non-cancer risk values were at an acceptable level for security guards and copy center employees. In order to lower the overall cancer risk levels of workers, the most effective method is to reduce the chemical concentration.