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Last updated
July 26, 2025

Ozone (O3)

Air pollution and ozone (O3) research focuses on this secondary pollutant that forms through complex atmospheric chemistry and poses significant health risks, particularly during warm weather. Studies demonstrate that ground-level ozone exposure contributes to respiratory disease, cardiovascular problems, and premature mortality, with effects that can persist long after exposure ends. The evidence reveals how ozone pollution disproportionately affects outdoor workers, children, and people with existing health conditions. Discover the research documenting ozone health impacts and why this pollutant requires comprehensive regional control strategies.
  • “Levels of ozone are increasing.” Heat waves worsen ozone pollution - seeing record-breaking heat waves (Ada Wright, Pallavi Pant, 2024)
  • Ground level/tropospheric ozone is 30-70% higher today than 100 years ago. Formed from chemical reactions of nitrogen oxides and VOCs in the sun which increase during higher temperatures. Leads to increased risk of acute and chronic respiratory illnesses, reduces crop yields (bad for food supply) (State of Global Air | 2024)
  • Ozone - 2020 - 93% world pop. lived in above WHO AQG for 60 ug/m3 aka 31 ppb (parts per billion) (State of Global Air | 2024)
  • Imported O3 represents 88.3% of all ozone-attributable deaths.  Ozone levels depend on tropospheric transport from distant sources, including the westerlies (Hicham Achebak et al., 2024)
  • Over 95% of Europe is exposed to ozone levels that exceed WHO guidelines (Hicham Achebak et al., 2024)
  • Half million premature deaths around world caused by ozone from methane (Kaveh Madani, 2024)
  • Warmer atmosphere is expected to increase O3 levels (UNECE, 2025)
  • PM2.5 and ozone are formed when Volatile Organic Compounds (VOCs) react with pollutants. Terpenoids are used by plants as chemical signals and antioxidants, but in the atmosphere are VOCs (James Dinneen, 2024).
    • 60% of ozone and secondary organic aerosol formation in LA is caused by biogenic terpenoid emissions - correlated with rising temperature (James Dinneen, 2024)

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