Journal-based CME Course: Association of Short-term Air Pollution Exposure With SARS-CoV-2 Infection Among Young Adults in Sweden

Activity ID

12667

Expires

April 22, 2025

Format Type

Journal-based

CME Credit

1

Fee

30

CME Provider: JAMA Network Open

Description of CME Course

Importance  Mounting ecological evidence shows an association between short-term air pollution exposure and COVID-19, yet no study has examined this association on an individual level.

Objective  To estimate the association between short-term exposure to ambient air pollution and SARS-CoV-2 infection among Swedish young adults.

Design, Setting, and Participants  This time-stratified case-crossover study linked the prospective BAMSE (Children, Allergy Milieu, Stockholm, Epidemiology [in Swedish]) birth cohort to the Swedish national infectious disease registry to identify cases with positive results for SARS-CoV-2 polymerase chain reaction (PCR) testing from May 5, 2020, to March 31, 2021. Case day was defined as the date of the PCR test, whereas the dates with the same day of the week within the same calendar month and year were selected as control days. Data analysis was conducted from September 1 to December 31, 2021.

Exposures  Daily air pollutant levels (particulate matter with diameter ≤2.5 μm [PM_2.5], particulate matter with diameter ≤10 μm [PM₁₀], black carbon [BC], and nitrogen oxides [NOx]) at residential addresses were estimated using dispersion models with high spatiotemporal resolution.

Main Outcomes and Measures  Confirmed SARS-CoV-2 infection among participants within the BAMSE cohort. Distributed-lag models combined with conditional logistic regression models were used to estimate the association.

Results  A total of 425 cases were identified, of whom 229 (53.9%) were women, and the median age was 25.6 (IQR, 24.9-26.3) years. The median exposure level for PM_2.5 was 4.4 [IQR, 2.6-6.8] μg/m³ on case days; for PM₁₀, 7.7 [IQR, 4.6-11.3] μg/m³ on case days; for BC, 0.3 [IQR, 0.2-0.5] μg/m³ on case days; and for NOx, 8.2 [5.6-14.1] μg/m³ on case days. Median exposure levels on control days were 3.8 [IQR, 2.4-5.9] μg/m³ for PM_2.5, 6.6 [IQR, 4.5-10.4] μg/m³ for PM₁₀, 0.2 [IQR, 0.2-0.4] μg/m³ for BC, and 7.7 [IQR, 5.3-12.8] μg/m³ for NOx. Each IQR increase in short-term exposure to PM_2.5 on lag 2 was associated with a relative increase in positive results of SARS-CoV-2 PCR testing of 6.8% (95% CI, 2.1%-11.8%); exposure to PM₁₀ on lag 2, 6.9% (95% CI, 2.0%-12.1%); and exposure to BC on lag 1, 5.8% (95% CI, 0.3%-11.6%). These findings were not associated with NOx, nor were they modified by sex, smoking, or having asthma, overweight, or self-reported COVID-19 respiratory symptoms.

Conclusions and Relevance  The findings of this case-crossover study of Swedish young adults suggest that short-term exposure to particulate matter and BC was associated with increased risk of positive PRC test results for SARS-CoV-2, supporting the broad public health benefits of reducing ambient air pollution levels.

Disclaimers

1. This activity is accredited by the American Medical Association.
2. This activity is free to AMA members.

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