The association between long-term exposure to ambient air pollutants and severe COVID-19 is uncertain. This study followed 4,660,502 adults from the general population in Catalonia, Spain in 2020. Cox proportional models were used to evaluate the association between annual averages of PM2.5, NO2, BC, and O3 at each participant's residential address and severe COVID-19. Higher exposure to PM2.5, NO2, and BC was associated with an increased risk of COVID-19 hospitalization, ICU admission, death, and hospital length of stay. Ozone showed positive associations with severe outcomes when adjusted by NO2. The study provides robust evidence linking long-term air pollutant exposure to severe COVID-19.

Otavio Ranzani, Anna Alari, Sergio Olmos, Carles Milà, Alex Rico, Joan Ballester, Xavier Basagaña, Carlos Chaccour, Payam Dadvand, Talita Duarte-Salles, Maria Foraster, Mark Nieuwenhuijsen, Jordi Sunyer, Antònia Valentín, Manolis Kogevinas, Uxue Lazcano, Carla Avellaneda-Gómez, Rosa Vivanco, Cathryn Tonne