Temporal Evolution, Source Apportionment, and Health Risks of Atmospheric Halocarbons: A Case Study in the Central Yangtze River Delta Region

Recently, the environmental impact of halocarbons has become increasingly concerning, particularly due to the growing influence of non-regulated halocarbons on stratospheric ozone depletion and their adverse health effects in the troposphere. Previous model studies have highlighted the importance of halocarbon emissions from the YRD. However, only several reports have discussed the long-term pollution characteristics and health risks of halocarbons in the YRD based on observational data. The continuous observation of halocarbons was conducted in the central part of the YRD (Shanxi site) from 2018 to 2023. The result showed that rise in halocarbon levels was primarily driven by alkyl halides, including dichloromethane (1.194 ppb to 1.831 ppb), chloromethane (0.205 ppb to 1.121 ppb), 1,2-dichloroethane (0.399 ppb to 0.772 ppb), and chloroform (0.082 ppb to 0.300 ppb). The PMF and CBPF analysis revealed that pharmaceutical manufacturing (37.0% to 60.2%), chemical raw material manufacturing (8.0% to 19.9%), solvent use in machinery manufacturing (12.4% to 24.7%), solvent use in electronic industry, and background sources were the main sources of halocarbons at the Shanxi site. Among them, the contributions of chemical raw material manufacturing, as well as of solvent use in machinery manufacturing and electronic industry, are increasing. These aspects are all dominated by local emissions. Furthermore, the carcinogenic risks of chloroform and 1,2-dichloroethane, which rank first in this regard, are increasing. Also, attention should be paid to solvent use in the electronic industry and the background. The probabilities of these activities coming with health risks that exceed the acceptable levels are 94.8% and 94.9%. This study enriches the regional observation data in the YRD region, offering valuable insights into halocarbon pollution control measures for policy development.