Emissions of two legacy per- and polyfluoroalkyl substances (PFAS) across the Chinese mainland fell sharply between 2016 and 2021, according to a new bottom-up inventory that tracks releases to air, water and soil at a 0.1° × 0.1° resolution. The study, published in Environmental Science and Ecotechnology, reports that perfluorooctane sulfonate (PFOS) emissions dropped by about 89% and perfluorooctanoic acid (PFOA) emissions by more than 99% over the six-year period.
The findings matter because PFOS and PFOA are persistent organic pollutants regulated under the Stockholm Convention. They can accumulate in the human body and have been linked to immunotoxicity, endocrine disruption, developmental effects and certain cancers. China has introduced measures including the PFOS Priority Sectors Reduction and Phase-Out Project and restrictions on sulfuramid, but earlier inventories often covered single years or selected regions, leaving consecutive annual trends and medium-specific releases poorly quantified.
Researchers from Peking University, Shanghai Jiao Tong University and Southern University of Science and Technology built the inventory using source-specific activity data, literature-derived emission factors and Monte Carlo uncertainty analysis, covering five PFOS and four PFOA source categories. The reductions coincided with regulatory restrictions and technological transitions in fluoropolymer manufacturing, metal plating, aqueous film-forming foams (AFFFs) and sulfuramid pesticides.
The study also documents a structural shift in where emissions originate. PFOS releases were dominated by use-related sources in 2016, while PFOA emissions were overwhelmingly production-related. By 2021, AFFFs dominated residual PFOS emissions and nearly all residual PFOA emissions, concentrating releases at industrial and firefighting sites rather than across dispersed pesticide and industrial uses. Water remained the principal receiving medium for both compounds.
Residual hotspots persisted in the Bohai Rim, Yangtze River Delta (YRD) and Pearl River Delta (PRD), overlapping 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 dense populations. Grid-level emission densities contracted sharply, yet relative spatial heterogeneity remained substantial.
The authors said the declines reflect a structural transformation in China's emission profile for legacy eight-carbon PFAS, driven by source-directed regulation and industrial transition, and that targeted control should prioritize remaining metal-plating and firefighting-related sources. They recommend prioritizing monitoring of PFOS sources linked to metal plating and firefighting, and PFOA hotspots near fluoropolymer facilities.
The inventory, detailed in the study available at 10.1016/j.ese.2026.100785, offers spatially explicit source terms for exposure assessment and environmental monitoring, particularly in the YRD and PRD. The authors caution that replacement PFAS were not included because consistent national activity data and process-specific emission factors remain unavailable, and they call for facility-level mass-balance measurements and China-specific process-level emission factors. Such work could help assess the health benefits of source-control strategies and inform future regulatory priorities.
