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COVID-19

Air Pollution Exposure Linked to Increased Risk of COVID-19

Strategic Insights

— 2 min read

Research conducted by the Environmental Research Group at Imperial College London has found a significant association between long-term air pollution exposure and the risk of SARS-CoV-2 infection, COVID-19 hospitalization, and mortality. The study analyzed data from cohort studies with individual-level information and found that exposure to particulate matter less than 2.5 aerodynamic diameter (PM) was associated with an increased risk of all three outcomes investigated.

The systematic review and meta-analysis, published in the journal Environmental Pollution, included 20 studies with a total of 1.8 million participants. The results showed that long-term PM exposure was associated with an increased risk of SARS-CoV-2 infection (RR: 1.04 [1.02-1.07]), COVID-19 hospitalization (RR: 1.11 [1.06-1.15]), and COVID-19 mortality (RR: 1.09 [1.03-1.15]) per 1 µg/m³ increase. Nitrogen dioxide (NO) exposure was also associated with an increased risk of COVID-19 hospitalization (RR: 1.02 [1.01-1.03]) and mortality (RR: 1.01 [1.01-1.02]) per 1 µg/m³ increase.

Key Takeaways:

  • Long-term air pollution exposure is associated with an increased risk of SARS-CoV-2 infection, COVID-19 hospitalization, and mortality.
  • Particulate matter less than 2.5 aerodynamic diameter (PM) exposure was associated with an increased risk of all three outcomes investigated.
  • Nitrogen dioxide (NO) exposure was associated with an increased risk of COVID-19 hospitalization and mortality.
  • The study analyzed data from 20 studies with a total of 1.8 million participants.
  • No associations were found for ozone (O) exposure.

Statistics:

  • 1.8 million participants were included in the analysis.
  • 20 studies were included in the systematic review and meta-analysis.
  • The risk of SARS-CoV-2 infection increased by 4% (RR: 1.04 [1.02-1.07]) per 1 µg/m³ increase in PM exposure.
  • The risk of COVID-19 hospitalization increased by 11% (RR: 1.11 [1.06-1.15]) per 1 µg/m³ increase in PM exposure.
  • The risk of COVID-19 mortality increased by 9% (RR: 1.09 [1.03-1.15]) per 1 µg/m³ increase in PM exposure.
  • Nitrogen dioxide (NO) exposure was associated with an increased risk of COVID-19 hospitalization (RR: 1.02 [1.01-1.03]) and mortality (RR: 1.01 [1.01-1.02]) per 1 µg/m³ increase.

Sources:

  • Investigating links between long-term air pollution exposure and the risk of SARS-CoV-2 infection, COVID-19 hospitalisation and mortality: a systematic review and meta-analysis of cohort studies. Environmental Pollution, 2025;386:127222.
  • Environmental Pollution. Elsevier Sci Ltd, 125 London Wall, London, England. (www.elsevier.com; www.journals.elsevier.com/environmental-pollution/)
  • NewsRx. Studies from Imperial College London Provide New Data on COVID-19. Ecology, Environment & Conservation. October 31, 2025; p 263.

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