Characterization and sources of volatile organic compounds (VOCs) during 2022 summer ozone pollution control in Shanghai, China

Abstract

An experimental study was conducted to evaluate the effectiveness of the measures for controlling ozone (O3) pollution in Jinshan District, Shanghai, China during the summer months of June 2022–August 2022. The study period was divided into a control period (CP) when measures were enforced and a non-control period (NCP) without interventions. The concentrations of volatile organic compounds (VOCs) were compared between the two periods, with the ranking of various types of identical VOCs, in which alkanes exhibited the highest (39.48%) concentrations, followed by aromatics (24.35%), halohydrocarbons (19.94%) and alkenes (16.23%). Compared to NCP, the mean levels of VOCs were 32.67% lower in CP, indicating the control measures significantly reduced the concentrations of VOCs during the months when control measures were in effect. The typical bimodal O3 pattern was eliminated during CP along with the absence of peak VOC levels between 10:00 Hrs and 16:00 Hrs, which surpassed the level of 40 μg/m3 during NCP. The analyses of O3 formation potential (OFP) and rate of loss of OH radicals (LOH) indicated that alkenes and aromatics were the most chemically active VOCs driving the production of O3. Following six types of sources were determined for VOCs using positive matrix factorization (PMF): (1) solvent use (8.2%); (2) fuel evaporation (25.1%); (3) petrochemical plant (17.3%); (4) LPG (20.1%); (5) industrial process (16.1%); (6) vehicular emissions (13.2%). Emissions from vehicles and solvent use declined by 19.21% and 15.43%, respectively, underscoring their importance as controllable VOC sources in Shanghai, China. Overall, the study demonstrated the effectiveness of regional control measures in improving air quality by reducing the production of O3 and related VOCs.