Characteristics, Sources and Health Risks Assessment of VOCs in Zhengzhou, China During Haze Pollution Season

Zhengzhou is one of the most haze-polluted cities in Central China with high organic carbon emission, which accounts for 15%-20% of particulate matter (PM) in winter and causes significantly adverse health effects. Volatile organic compounds (VOCs) are the precursors of secondary PM and O formation. An investigation of characteristics, sources and health risks assessment of VOCs was carried out at the urban area of Zhengzhou from 1 to 31 December, 2019. The mean concentrations of total detected VOCs were 48.8 ± 23.0 ppbv. Alkanes (22.0 ± 10.4 ppbv), halocarbons (8.1 ± 3.9 ppbv) and aromatics (6.5 ± 3.9 ppbv) were the predominant VOC species, followed by alkenes (5.1 ± 3.3 ppbv), oxygenated VOCs (3.6 ± 1.8 ppbv), alkyne (3.5 ± 1.9, ppbv) and sulfide (0.5 ± 0.9 ppbv). The Positive Matrix Factorization model was used to identify and apportion VOCs sources. Five major sources of VOCs were identified as vehicular exhaust, industrial processes, combustion, fuel evaporation, and solvent use. The carcinogenic and non-carcinogenic risk values of species were calculated. The carcinogenic and non-carcinogenic risks of almost all air toxics increased during haze days. The total non-carcinogenic risks exceeded the acceptable ranges. Most VOC species posed no non-carcinogenic risk during three haze events. The carcinogenic risks of chloroform, 1,2-dichloroethane, 1,2-dibromoethane, benzyl chloride, hexachloro-1,3-butadiene, benzene and naphthalene were above the acceptable level (1.0  ×  10) but below the tolerable risk level (1.0  ×  10). Industrial emission was the major contributor to non-carcinogenic, and solvent use was the major contributor to carcinogenic risks.