{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,5]],"date-time":"2026-11-05T19:26:51Z","timestamp":1793906811635,"version":"4.8.0"},"reference-count":38,"publisher":"Oxford University Press (OUP)","license":[{"start":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T00:00:00Z","timestamp":1791849600000},"content-version":"am","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"funder":[{"DOI":"10.13039\/501100020771","name":"Young Scientists Fund of the National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["22206049"],"award-info":[{"award-number":["22206049"]}],"id":[{"id":"10.13039\/501100020771","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Fundamental Research Funds for Central Universities","award":["2026MS195"],"award-info":[{"award-number":["2026MS195"]}]},{"name":"the Science and Technology Planning Project of Hebei Academy of Sciences","award":["26B103"],"award-info":[{"award-number":["26B103"]}],"id":[{"id":"https:\/\/ror.org\/03xqveg17","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Environmentally persistent free radicals (EPFRs) in atmospheric particulate matter (PM) are of increasing concern because of their potential health risks. This study systematically investigated the occurrence and characteristics of EPFRs in PM2.5 (PM with an aerodynamic diameter \u22642.5\u2009\u03bcm), PM10 (PM with an aerodynamic diameter \u226410\u2009\u03bcm), and total suspended particles. Mass-normalized EPFR concentrations and g factors were determined, human exposure was evaluated using an equivalent-cigarette model, and size-dependent formation mechanisms were examined through laboratory simulations. In the simulation system, SiO2, catechol, and ZnO were used as the surrogate particle, organic precursor, and transition-metal component, respectively, while scanning electron microscopy, energy-dispersive x-ray spectroscopy, Brunauer\u2013Emmett\u2013Teller analysis, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy were applied to characterize particle morphology, elemental composition, and surface properties. The EPFRs in atmospheric PM were identified mainly as carbon-centered radicals with adjacent oxygen-containing functional groups. The highest EPFR concentration was PM2.5 (8.05\u2009\u00d7\u20091016 spins\u00b7g\u22121) and g factor (2.00337), indicating that finer particles contained more abundant radicals and a stronger contribution from oxygen-related species. The estimated daily equivalent-cigarette exposure was 0.326 cigarettes day\u22121 for PM2.5 and 0.346 cigarettes day\u22121 for PM10. Laboratory simulations showed that smaller particles generated more EPFRs and exhibited higher g factors because of their larger specific surface area and more accessible reactive sites. The EPFR concentration on 2-\u03bcm particles was 1.63 and 16.3 times higher than that on 10-\u03bcm and 150- to 380-\u03bcm particles, respectively. Zinc\u00a0also played a key role in promoting EPFR formation. Integrating field observations and laboratory simulations, this study assesses size-segregated EPFR exposure and Zn\u2019s role in EPFR formation in PM2.5. These findings underscore the need for coordinated control of heavy metals and organic species and support toxicity-oriented PM control.<\/jats:p>","DOI":"10.1093\/etojnl\/vgag274","type":"journal-article","created":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T11:47:12Z","timestamp":1791892032000},"source":"Crossref","is-referenced-by-count":0,"title":["Size-dependent characteristics, exposure risk, and formation mechanisms of environmentally persistent free radicals in atmospheric particulate matter"],"prefix":"10.1093","author":[{"given":"Mingyu","family":"Li","sequence":"first","affiliation":[{"name":"Hebei Key Laboratory of New Energy Environmental Safety and Resource Utilization, Department of Environment Science & Engineering, North China Electric Power University , Baoding,","place":["China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yixian","family":"Long","sequence":"additional","affiliation":[{"name":"Hebei Key Laboratory of New Energy 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Baoding,","place":["China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chun-Gang","family":"Yuan","sequence":"additional","affiliation":[{"name":"Hebei Key Laboratory of New Energy Environmental Safety and Resource Utilization, Department of Environment Science & Engineering, North China Electric Power University , Baoding,","place":["China"]},{"name":"Yanzhao Electric Power Laboratory, North China Electric Power University , Baoding,","place":["China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fucong","family":"Sui","sequence":"additional","affiliation":[{"name":"Hebei Key Laboratory of New Energy Environmental Safety and Resource Utilization, Department of Environment Science & Engineering, North China Electric Power University , Baoding,","place":["China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yiwen","family":"Shen","sequence":"additional","affiliation":[{"name":"Institute of Geographical Sciences, Hebei Academy of 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