Comprehensive Analysis of Vocs in an Industrial Harbor City: Spatiotemporal Distribution, Health Risk Assessment, and Potential Sources

Abstract

Volatile organic compounds (VOCs) measurements during the worst air quality season of 2020-2022 were conducted at three distinct sites within Kaohsiung Harbor, Taiwan's largest harbor and a significant hub in Asia. Spatiotemporal variations, origins, ozone formation potential (OFP), and health risks of VOCs were investigated and discussed. The results indicate a decrease in average total VOC (TVOC) concentrations (ppbv) over the study period: 37.9 ± 4.5 in 2020, 23.3 ± 9.9 in 2021, and 23.3 ± 2.6 in 2022. Dominant VOC components were C2-VOCs and aromatics, which made up more than 50% of TVOCs. According to diagnostic ratio analysis, local anthropogenic emissions, such as industrial and ship/vehicle emissions around harbor area, were main causes. Four sources were identified by positive matrix factorization (PMF), with industrial activities (33.7%), followed by vehicle and ship emissions (30.6%), solvent usages (21.1%), and fuel evaporations (14.6%). OFP results indicated that toluene was primary OFP contributor, accounting for an average of 30.4%, followed by C2-VOCs at 16.2% and m/p-xylenes at 12.5%, collectively contributing nearly 60% to OFP. These OFP contributors were significantly attributed to vehicle/ship emissions and solvent usages. Cumulative non-carcinogenic hazard index were below safe level of 1, whereas carcinogenic risks of 1,2-dichloroethane and 1,3-butadiene were higher than the acceptable risk level (1 × 10-6) in three years and in 2020, respectively. Industrial emissions could mainly contribute to carcinogenic risks in Kaohsiung Harbor and surrounding area. The results are conducive to developing control strategies for VOCs to reduce human exposure to ambient air.

Keywords: Carcinogenic risks, Green port, Ozone formation, Pollution sources, Volatile organic compounds.