Volatile organic compounds in Shihezi, China, during the heating season: pollution characteristics, source apportionment, and health risk assessment

From November 2018 to March 2019, the mixing ratios of 57 types of volatile organic compounds (VOCs) were measured using gas chromatography-mass spectrometry in Shihezi. The results depicted that the average mixing ratios of VOCs were 58.48 ppbv and alkanes (34.15 ppbv) showed the largest contribution, followed by ethyne (20.16 ppbv), alkenes (2.62 ppbv), and aromatics (1.55 ppbv). Based on the positive matrix factorization (PMF) model result, coal burning (39.83%), traffic-related exhaust (26.87%), liquefied petroleum gas/natural gas usage (LPG/NG) (17.32%), fuel evaporation and paint usage (9.02%), and industrial emission (6.96%) were distinguished. Secondary formation potential was applied to demonstrate the probability of secondary pollution; the results indicated that alkanes (27.30 ppbv) and alkenes (21.42 ppbv) played leading roles in ozone formation potential (OFP) and the contributions of alkanes (1.05 mu g/m(3)) and aromatics (0.99 mu g/m(3)) were nearly equal for secondary organic aerosol formation potential (SOAFP) under high-NOx condition. However, under a low-NOx condition, aromatics (2.12 mu g/m(3)) dominated, and the contribution of alkanes (1.05 mu g/m(3)) was lower. Monte Carlo simulation results showed that exposure to 1,3-butadiene and benzene may contribute potential carcinogenic risks to local residents; PMF results showed that reducing traffic-related and industrial emissions as well as coal burning was more effective in controlling carcinogenic risks. This study provides a crucial theoretical basis for decision-makers to minimize local air pollution more effectively.