Indoor PM10 and its heavy metal composition at a roadside residential environment, Phitsanulok, Thailand

Abstract

The concentrations of PM₁₀ were measured both indoors and outdoors at 10 roadside residential buildings in Phitsanulok, Thailand during the dry and wet seasons of 2014. Seven trace metals (Zn, Fe, Pb, Cd, Ni, Cu and Cr) were also analysed in PM₁₀. The monthly average concentrations of indoor and outdoor PM₁₀ were 41.5 to 105.3 μg m^–3 and 95.2 to 145.1 μg m^–3, respectively. PM₁₀ concentrations were significantly higher during the dry season compared to the wet season. The indoor/outdoor (I/O) ratios were less than one indicating that the particulate matter originates from the outdoor environment. Overall, the average concentrations of heavy metals in PM10 ranged from 0.2 to 2.7 μg m^–3 and 0.5 to 7.1 μg m^–3 for the indoor and outdoor environments, respectively. A strong positive correlation in indoor PM₁₀ was found between Zn and Cu, Zn and Ni, and Cu and Ni. Zn and Ni, Pb and Cu, Cu and Ni, Cd and Ni, and Zn and Cu showed strong positive correlations in the outdoor environment. The enrichment factors of Zn, Cu, Pb, Cr and Ni were less than one suggesting that the metals in indoor PM₁₀ have originated from crustal materials. For the health risk assessment, Cr was found to have the highest excess cancer risk in an evaluation using an Integrated Risk Information System.