Air pollution may boost risk of longer-term long-COVID symptoms, research suggests

COVID-19
Woman holding up cloth to face to avoid air pollution from cars

Werawad Ruangjaroon / iStock

Exposure to small- or fine-particle air pollution may predispose COVID-19 survivors to a longer duration of persistent symptoms by increasing the severity of the infection, among other contributing factors, finds a study led by the Barcelona Institute for Global Health (ISGlobal).

The researchers followed 2,853 adult COVID-19 survivors and healthy controls aged 40 to 65 years in the Catalonia region of northeastern Spain who completed three online questionnaires in 2020, 2021, and 2023 on COVID-19 infections, vaccination status, health status, and sociodemographic factors. The team also estimated participants' exposure to nighttime traffic noise, particulate matter, ozone, nitrogen dioxide, green spaces, and artificial light at night.

The findings were published last week in Environmental Health Perspectives.

Vaccination conferred protection

Roughly 1 in 4 (24.5%) COVID-19 patients reported persistent symptoms lasting at least 3 months, and 5% had symptoms for 2 years or longer. Risk factors were female sex (27.6% vs 19.4% in men), lower educational attainment (29.2% vs 22.2% of those with a university education), underlying medical conditions (33.3% vs 19.7% of those without them), and severe COVID-19 infection (71.8% vs 25.1% of those with mild or moderate cases). 

Vaccination conferred a protective effect, with 15.4% of vaccinees developing long COVID, compared with 46.0% of the unvaccinated.

We previously found that air pollution exposure is linked to a higher risk of severe COVID-19 and a lower vaccine response, but there are very few studies on long-COVID and the environment.

Manolis Kogevinas, MD, PhD

Exposure to airborne particulate matter of no more than 10 or 2.5 microns in diameter was tied to a modestly increased risk of long COVID among participants who reported having long COVID in 2021 and still had symptoms the week before the 2023 survey. Unlike air pollution, factors such as nearby green spaces or traffic noise seemed to have little effect.

"We previously found that air pollution exposure is linked to a higher risk of severe COVID-19 and a lower vaccine response, but there are very few studies on long-COVID and the environment,” senior author Manolis Kogevinas, MD, PhD, of ISGlobal, said in an institute news release.

While air pollution may not directly cause long COVID, it could make the infection more severe, which raises the risk of lingering symptoms. "This hypothesis is supported by the association between particulate matter and the most severe and persistent cases of long-COVID, but not with all cases of long-COVID,” first author Apolline Saucy, PhD, of ISGlobal, said in the release.

The researchers called for future research on long-COVID subtypes and symptoms. 

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