Aromatic hydrocarbons in urban and suburban atmospheres in Central China : spatiotemporal patterns, source implications, and health risk assessment

Abstract

Ambient aromatic hydrocarbons (AHs) are hazardous air pollutants and the main precursors of ozone (O-3). In this study, the characteristics of ambient AHs were investigated at an urban site (Ziyang, ZY) and a suburban site (Jiangxia, JX) in Wuhan, Central China, in 2017. The positive matrix factorization (PMF) model was used to investigate the sources of AHs, and a health risk assessment was applied to estimate the effects of AHs on human health. The concentrations of total AHs at ZY (2048 +/- 1364 pptv) were comparable (p > 0.05) to that (2023 +/- 1015 pptv) at JX. Source apportionment results revealed that vehicle exhaust was the dominant source of both, total AHs, and toluene, contributing 51.9 +/- 13.1% and 49.3 +/- 9.5% at ZY, and 44.7 +/- 12.6% and 43.2 +/- 10.2% at JX, respectively. Benzene was mainly emitted from vehicle exhaust at ZY (50.2 +/- 15.5%), while it was mainly released from biomass and coal burning sources at JX (50.6 +/- 16.7%). The health risk assessment results indicated that AHs did not have a significant non-carcinogenic risk, while the carcinogenic risks of benzene exceeded the regulatory limits set by the USEPA for adults (1 x 10(-6)) at both sites. Hence, controlling the emissions of vehicular and biomass/coal burning sources will be an effective way to reduce ambient AHs and the health risk of benzene exposure in this region. These findings will enhance our knowledge of ambient AHs in Central China and be helpful for local governments to formulate air pollution control strategies.