Characterization, source apportionment and associated health risk assessment of respirable air particulates in Metro Manila, Philippines

Coarse (PM10) and fine (PM2.5) aerosols were sampled from June to November 2016 at three different sites in Metro Manila Philippines (Valenzuela, NAMRIA, and MMDA). PM2.5 average levels in all sites exceeded the World Health Organization annual and daily limits, indicating that the ambient air qualities in all sites were unhealthy. Black Carbon (BC), a fingerprint of incomplete combustion, constituted 31-46% of PM2.5. Multi-element analysis of PM indicated that the sulfur, lead, and zinc had substantial contributions to PM2.5, with the highest level found in Valenzuela. Receptor modeling highlighted six important sources: vehicular emissions, biomass burning, industrials, secondary sulfur, sea spray, and fine soil. Among the sources, vehicular emission was the most dominant source, comprising 20-35% of the apportioned sources. An industrial source, predominantly with Zn and Pb, was seen in Valenzuela, contributing about 5.4% of its PM2.5. The health risks of fine aerosol, BC, and major elements were evaluated also in this study. Elements studied showed negligible potential (HQ < 1) to cause non-carcinogenic health effects and very low (<1 x 10(-6)) carcinogenic health effects to children and adults. The observed trend for carcinogenic risks of PM2.5 in children was Valenzuela > MMDA > NAMRIA while a medium carcinogenic risk was observed for adults at all sites (CR > 1 x 10(-5)). The trend for PM2.5 average HQ values in both age groups was Valenzuela > MMDA > NAMRIA. Our results showcased varying levels and sources of PM and its components that can impact the health upon exposure and should be addressed in future policies to safeguard public health.