{
  "abstract": "Reactive oxygen species (ROS) formation by atmospheric fine particulate matter (PM) is widely implicated in adverse health effects, yet the molecular determinants of particle-level ROS formation remain poorly constrained, largely due to the chemical complexity of organic aerosol (OA). Here, we link ROS formation to molecular-level OA composition by applying a maximum carbonyl ratio-Van Krevelen framework to ambient fine PM collected from four Chinese megacities, a German semi-urban site, a boreal forest, and laboratory-generated secondary organic aerosol (SOA) from multiple precursors. Using ultrahigh-resolution mass spectrometry combined with hydrogen peroxide (H ₂ O ₂ ) and radical measurements, we show the intrinsic ROS (H ₂ O ₂ + radicals) formation potential of fine PM is governed by OA composition rather than particle mass. Volume-normalized ROS yields increase with fine PM mass concentration and dominate overall exposure in polluted urban environments. In contrast, mass-normalized ROS yields vary independently of particle loading and are strongly driven by the balance between relative fractions of oxidized organic compounds (RF OOC ) and unsaturated organic compounds (RF UOC ), i.e., RF OOC / RF UOC . Across urban sites, mass-normalized ROS and H ₂ O ₂ yields exhibit strong correlations with RF OOC / RF UOC , establishing this metric as a robust predictor of ROS formation. Remote, biogenic-influenced aerosols exhibit higher RF OOC / RF UOC and higher ROS yields per unit mass, whereas urban aerosols exhibit the opposite behavior. Laboratory SOA further supports these composition-reactivity relationships, with OOC-rich biogenic SOA exhibiting the highest ROS yields. This study reveals molecular-level characteristics in governing aerosol ROS formation and introduces a framework for assessing health-relevant aerosol oxidative activity of chemically complex OA.",
  "abstract_shown": true,
  "affiliations": [
    "China Agricultural University (Beijing, China)",
    "Helmholtz-Zentrum Hereon (Geesthacht, Germany)",
    "Max Planck Institute for Chemistry (Mainz, Germany)"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 10,
  "authors": [
    {
      "name": "Fobang Liu",
      "orcid": "0000-0002-9914-165X"
    },
    {
      "name": "Yun Zhang"
    },
    {
      "name": "Siyao Yue"
    },
    {
      "name": "Helmi-Marja K. Keskinen",
      "orcid": "0000-0003-3614-0542"
    },
    {
      "name": "Tuukka Petäjä",
      "orcid": "0000-0002-1881-9044"
    },
    {
      "name": "Markku Kulmala",
      "orcid": "0000-0003-3464-7825"
    },
    {
      "name": "Pingqing Fu",
      "orcid": "0000-0001-6249-2280"
    },
    {
      "name": "Thorsten Hoffmann",
      "orcid": "0000-0003-0939-271X"
    },
    {
      "affs": [
        0
      ],
      "name": "Kai Wang",
      "orcid": "0000-0002-1305-6789"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Haijie Tong",
      "orcid": "0000-0001-9887-7836"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/daaj00jdzj00e.bib",
  "cited_by": 0,
  "doi": "10.5194/acp-26-14655-2026",
  "fulltext_url": null,
  "id": "daaj00jdzj00e",
  "issns": [
    "1680-7324"
  ],
  "landing_url": "https://acp.copernicus.org/articles/26/14655/2026/",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1902|Atmospheric chemistry and aerosols"
    ]
  ],
  "openalex": "W7169868761",
  "pdf_url": "https://acp.copernicus.org/articles/26/14655/2026/acp-26-14655-2026.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-16",
  "publisher": "Copernicus GmbH",
  "ris": "https://research.draconitic.com/paper/daaj00jdzj00e.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:34Z",
      "native_id": "10.5194/acp-26-14655-2026",
      "source": "crossref",
      "url": "https://acp.copernicus.org/articles/26/14655/2026/"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "openalex:1902|Atmospheric chemistry and aerosols",
      "subfield": "atmospheric"
    }
  ],
  "title": "Linking molecular composition of organic aerosols to reactive oxygen species formation using an MCR-VK framework",
  "title_text": "Linking molecular composition of organic aerosols to reactive oxygen species formation using an MCR-VK framework",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:20:34Z",
  "url": "https://research.draconitic.com/paper/daaj00jdzj00e",
  "venue": "Atmospheric Chemistry and Physics",
  "versions": [
    {
      "doi": "10.5194/egusphere-2026-3897",
      "pid": null,
      "relation": "preprint",
      "title": null,
      "venue": null
    }
  ]
}