Indoor PM0.1 and PM2.5 in Hanoi: Chemical characterization, source identification, and health risk assessment

This study attempted to provide comprehensive insights into the chemical composition, source identification, and health risk assessment of indoor particulate matter (PM) in urban areas of Vietnam. Three hundred and twenty daily samples of PM0.1 and PM2.5 were collected at three different types of dwellings in Hanoi in two seasons, namely summer and winter. The samples were analyzed for 10 trace elements (TEs), namely Cr, Mn, Co, Cu, Ni, Zn, As, Cd, Sn, and Pb. The daily average concentrations of indoor PM0.1 and PM2.5 in the city were in the ranges of 7.0-8.9 mu g/m3 and 43.3-106 mu g/m3, respectively. The average concentrations of TEs bound to indoor PM ranged from 66.2 ng/m3 to 216 ng/m3 for PM0.1 and 391 ng/m3 to 2360 ng/m3 for PM2.5. Principle component analysis and enrichment factor were applied to identify the possible sources of indoor PM. Results showed that indoor PM2.5 was mainly derived from outdoor sources, whereas indoor PM0.1 was derived from indoor and outdoor sources. Domestic coal burning, industrial and traffic emissions were observed as outdoor sources, whereas household dust and indoor combustion were found as indoor sources. 80% of PM2.5 was deposited in the head airways, whereas 75% of PM0.1 was deposited in alveolar region. Monte Carlo simulation indicated that the intake of TEs in PM2.5 can lead to high carcinogenic risk for people over 60 years old and unacceptable non-carcinogenic risks for all ages at the roadside house in winter.