Risk of Long COVID Increases with Air Pollution

Zhenin Yu, PhD

A new study published in the Lancet Regional Health found a positive association between ambient air pollution and long COVID among young adults in Sweden suggesting ambient long-term particulate matter ≤2.5 μm (PM_2.5) exposure may pose a risk to this population.¹

Post-COVID-19 conditions like long COVID have become a public health concern, though there’s still limited evidence about the impact of their underlying risk factors. These findings support the need for continuous improvement of air quality, investigators wrote.

The other air pollutants examined in the study also displayed positive associations which remained consistent across sensitivity analyses, with stronger associations generally observed among participants with asthma and those who had COVID during 2020.

Persistent COVID-19 and PM_2.5 Air Pollution

To examine the ambient air pollution level, particulate matter ≤10 μm (PM₁₀), black carbon (BC), and nitrogen oxides (NO_x) were assessed along with PM_2.5. Estimations were made with individual-level addresses and dispersion modeling conducted by the team of investigators led by Zhebin Yu, Institute of Environmental Medicine, Karolinska Institutet.

A total of 116 (15.4%) of the 753 participants with SARS-CoV-2 infection included in the study, reported having long COVID. The most common symptoms were altered smell or taste (10.6%), dyspnea (4.8%), and fatigue (4.5%).

In addition to a link between the risk of long COVID and long-term exposure to PM_2.5 air pollution, data showed the median annual level of PM_2.5 exposure increased since before the pandemic. In 2019 the median annual PM_2.5 exposure was 6.39 (interquartile range [IQR] 6.06–6.71) μg/m3.

Increases of 1.28 for long COVID, 1.65 for dyspnea symptoms, and 1.29 for altered smell or taste were revealed with adjusted Odds Ratios (95% confidence intervals) of PM_2.5.

Investigating the link between air pollution and long COVID

To investigate the associations of air pollution exposure with long COVID, data were collected from the Children, Allergy, Environment, Stockholm, Epidemiology (BAMSE) cohort, a long-term follow-up study of Swedish children born between 1994 and 1996, with a focus on the relationship between environmental exposures and allergy and asthma development.

From October 2021 to February 2022, the participants answered a web-based questionnaire that addressed persistent symptoms following acute infections with SARS-CoV-2. Long COVID was defined as the presence of symptoms lasting for 2 months or longer after a confirmed infection.

As of September 2022, the COVID-19 pandemic has caused With more than 612 million confirmed cases and over 6.5 million deaths worldwide, as of September 2022, concerns have increased regarding persistent symptoms and long-term risk factors of the virus.

Following infection, individuals typically continue to experience fatigue, chronic cough, and altered smell and taste, which can affect them for several months. Investigators emphasized the necessity of ongoing initiatives to improve air quality and reduce air pollution in order to reduce the burden of long COVID risk, particularly for this population.

“These findings shed light on the complex pathogenesis of long-term post-COVID-19 symptoms and ubiquitous adverse health effects of air pollutants,” the team wrote. “Since ambient air pollution is a modifiable risk factor through national or regional public health regulations as well as individual interventions, our results support the broad public health benefits of continuous efforts to reduce ambient air pollution levels.”

References:

1. Yu Z, Ekström S, Bellander T, et al. Ambient air pollution exposure linked to long COVID among young adults: a nested survey in a population-based cohort in Sweden. The Lancet Regional Health - Europe. 2023; 100608.