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Air pollution in relation to COVID-19 morbidity and mortality: A large population-based cohort study in Catalonia, Spain (COVAIR-CAT)

Principal Investigator: 

Barcelona Institute for Global Health (ISGlobal), Spain

This study will test whether long- or short-term exposure to air pollution increases the risk of COVID-19 hospital admissions or mortality and identify vulnerable subgroups among 6 million residents of Catalonia, Spain. The investigators will link air pollution exposures to residents’ addresses and inpatient and outpatient electronic medical records.

Funded under

Poster abstract for HEI Annual Conference 2023

Air pollution in relation to COVID-19 morbidity and mortality: a large population-based study in Catalonia, Spain (COVAIR-CAT)

Cathryn Tonne1, Anna Alari1, Carla Avellaneda2, Joan Ballester1, Xavier Basagaña1, Carlos Chaccour1, Payam Dadvand1, Talita Duarte-Salles3,  Maria Foraster1,  Carles Milà1, Mark Nieuwenhuijsen1,  Sergio Olmos1, Otavio Ranzani1, Alex Rico1, Jordi Sunyer1,  Antònia Valentín1, Rosa Vivanco4

1ISGlobal, Barcelona, Spain; 2Institut Hospital del Mar d’Investigacions Mèdiques, 3IDIAPJGOL, Barcelona, Spain Barcelona, Spain; 4Agency for Health Quality and Assessment of Catalonia, Barcelona, Spain

Background. Evidence from epidemiological studies based on individual-level data indicate that air pollution may be associated with COVID-19 severity. We aimed to test whether: 1) long-term exposure to air pollution is associated with COVID-19 hospital admission or mortality in the general population; 2) short-term exposure to air pollution is associated with COVID-19 hospital admission following COVID-19 diagnosis; 3) there are vulnerable population subgroups; and 4) the influence of long-term air pollution exposure on COVID-19 hospital admissions and mortality differed from that for non-COVID-19 respiratory infections.

Methods. We constructed a cohort covering nearly the full population of Catalonia through electronic health record linkage, with follow up from 1 Jan 2015 to Dec 31 2020. Exposures at residential address were estimated using newly developed spatio-temporal models of PM2.5, PM10, NO2, and maximum 8h-average O3 at a spatial resolution of 250m for the period 2018-2020.

Results. The general population cohort included 4,660,502 individuals; in 2020 there were 340,608 COVID-19 diagnoses, 47,174 COVID-19 hospital admissions, and 10,001 COVID-19 deaths. Mean (sd) annual exposures were 13.8 (2.2) µg/m3 for PM2.5, 26.2 (10.3) µg/m3 for NO2, and 91.6 (8.2) µg/m3 for O3. In aim 1, an increase of 16.1 μg/m3 NO2 was associated with 25% (95% CI, 22-29) increase in hospitalizations and 18% (95% CI, 10-27) increase in deaths. In aim 2, cumulative air pollution exposure over the previous seven days was positively associated with COVID-related hospitalization. Lag-specific results indicated that cumulative-exposure associations were driven by exposure on the day of the hospital admission. Associations between short-term exposure to air pollution and COVID-19 hospitalization were similar in all population sub-groups. In aim 3, individuals with lower socioeconomic position had greater risk of hospitalization due to long-term air pollution (e.g., 43%, 95% CI, 37-49 in the upper vs 27%, 95% CI, 23-32 in the lowest tercile of area-level deprivation index per 16.1 μg/m3 of NO2), while those with co-morbid conditions generally had lower risk of hospitalization due to air pollution (e.g., 20%, 95% CI, 17-23 for those with hypertension vs 30%, 95% CI, 27-33 for those without hypertension per 3.2 μg/m3 of PM2.5). Aim 4 analyses are ongoing.

Conclusions. Linkage across several electronic health record databases allowed for the construction of a large population-based cohort, tracking COVID-19 cases from primary care and testing data to hospital admissions, and/or death. Long- and short-term exposure to ambient air pollution were positively associated with severe COVID-19 events. The effects of long-term air pollution exposure on COVID-19 severity was greater among those with lower individual- and area-level socioeconomic position.