biostudies-literatureUnknown14(2)Yan HClean heating policies were implemented in rural areas of Shaanxi Province in 2017 to alleviate severe air pollution. To evaluate their impacts on bioavailability of PM_2.5-bound metals, the influence of emission sources and aerosol acidity on PM_2.5-bound metal solubility was explored in Xi'an over three policy-defined periods between 2016 and 2021. Results showed that aerosol pH increased progressively from 4.81 ± 1.82 to 5.29 ± 1.79 following policy implementation, closely associated with reductions in SO₂ and NO₂ concentrations due to emission controls. Metal concentrations decreased significantly over the study period. In contrast, metal solubility exhibited clear source-dependent variations. Solubilities of metals associated with coal combustToxics168https://www.ebi.ac.uk/biostudies/studies/S-EPMC12945187biostudies-literatureChanges in Metal Solubility in PM<sub>2.5</sub> in Xi'an City Under Clean Heating Policies: Effects of Emission Source and Aerosol Acidity.PMC12945187Dong YLi CLiu PXue ZXue JXu HYan HSun JfalseChanges in Metal Solubility in PM<sub>2.5</sub> in Xi'an City Under Clean Heating Policies: Effects of Emission Source and Aerosol Acidity.Clean heating policies were implemented in rural areas of Shaanxi Province in 2017 to alleviate severe air pollution. To evaluate their impacts on bioavailability of PM_2.5-bound metals, the influence of emission sources and aerosol acidity on PM_2.5-bound metal solubility was explored in Xi'an over three policy-defined periods between 2016 and 2021. Results showed that aerosol pH increased progressively from 4.81 ± 1.82 to 5.29 ± 1.79 following policy implementation, closely associated with reductions in SO₂ and NO₂ concentrations due to emission controls. Metal concentrations decreased significantly over the study period. In contrast, metal solubility exhibited clear source-dependent variations. Solubilities of metals associated with coal combust2026-01-01T00:00:00Z2026 Feb2026-07-11T03:13:10.734Z2026-07-11T03:11:21.518ZS-EPMC129451874174584210.3390/toxics14020168