ArticleBMJ open respiratory research2026
Association between short-term exposure to air pollution and COVID-19: a case-crossover cohort study.
Article in BMJ open respiratory research, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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12 authors.
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Abstract
objectiveTo investigate associations between short-term fluctuations in urban background air pollution and the incidence of COVID-19 across three Swedish cities using detailed individual-level data.
methodsA case-crossover analysis was conducted using individual-level data from a prospective cohort of adults across three Swedish cities (Stockholm, Gothenburg and Uppsala), including 3999 confirmed COVID-19 cases. Subjects were classified as cases on the date of their first positive PCR test, which occurred between 7 March 2020 and 26 January 2022. Exposure data for daily levels of PM2.5, PM10 and NO
resultsA significant association was observed between elevated PM2.5 levels and testing positive for COVID-19 on the same day (lag 0), with an OR of 1.084 (95% CI 1.011 to 1.162) per IQR (3.3 µg/m³) increase. Similar lag 0 effects were found across the three cities. For PM10, the most consistent associations were observed at lag 3. For NO
conclusionsOur findings suggest that short-term fluctuations in air pollution, particularly for PM2.5, are associated with the timing of confirmed COVID-19 cases. A possible explanation for the short lag association is that air pollution exacerbates symptoms, prompting individuals to seek testing, rather than directly facilitating new infections.
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