A new bottom-up, multimedia emission inventory for the Chinese mainland shows that emissions of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) fell by approximately 89% and more than 99%, respectively, between 2016 and 2021. The study, published in Environmental Science and Ecotechnology, provides the first consecutive annual, 0.1° × 0.1° resolution mapping of these persistent organic pollutants across air, water, and soil. While the overall reductions are striking, the research highlights that residual emissions are increasingly concentrated in specific industrial and firefighting sites, often overlapping with dense populations, which poses ongoing health and environmental risks.
The inventory, developed by researchers from Peking University, Shanghai Jiao Tong University, and Southern University of Science and Technology, tracked five PFOS and four PFOA source categories using source-specific activity data, literature-derived emission factors, and Monte Carlo uncertainty analysis. The authors attribute the sharp declines to regulatory restrictions and technological transitions in fluoropolymer manufacturing, metal plating, aqueous film-forming foams (AFFFs), and sulfuramid pesticides. In 2016, PFOS emissions were dominated by use-related releases, while PFOA emissions were overwhelmingly production-related. By 2021, AFFFs dominated residual PFOS and nearly all residual PFOA emissions, indicating a structural shift from dispersed pesticide and industrial uses toward concentrated firefighting and manufacturing sites.
Despite the national reductions, the spatial structure of emissions has reshaped, with hotspots persisting in the Bohai Rim, Yangtze River Delta (YRD), and Pearl River Delta (PRD). These areas coincide with dense populations in eastern and southeastern industrial zones. A population-weighted emission index identified the YRD and PRD as priority areas where residual sources coincide with high human exposure potential. Water remained the principal receiving medium for both compounds, underscoring the importance of monitoring aquatic systems. The authors emphasize that targeted control should prioritize remaining metal-plating and firefighting-related sources, and recommend monitoring PFOA hotspots near fluoropolymer facilities.
The study's implications extend beyond China's borders. PFOS and PFOA are regulated under the Stockholm Convention due to their persistence, bioaccumulation, and links to immunotoxicity, endocrine disruption, developmental effects, and certain cancers. The inventory offers spatially and temporally resolved source terms for multimedia fate modeling, exposure assessment, and policy evaluation, particularly in the YRD and PRD. The authors call for facility-level mass-balance measurements and China-specific process-level emission factors to improve future inventories, and for expanding compound coverage to replacement PFAS as nationally consistent activity data become available. Such work could help assess the health benefits of source-control strategies and inform future regulatory priorities.
The research was supported by the National Natural Science Foundation of China and the Fundamental and Interdisciplinary Disciplines Breakthrough Plan of the Ministry of Education of China. The full study is available at 10.1016/j.ese.2026.100785.
