Air pollution increases the duration of Long COVID symptoms

Exposure to air pollutants (PM_2.5 and PM₁₀) is associated with an increased risk of persistent long-term COVID symptoms, in part due to its influence on the severity of acute infection. This is the main conclusion of a study carried out by the Barcelona Institute for Global Health (ISGlobal), a center supported by the “la Caixa” Foundation, in collaboration with the Germans Trias i Pujol Research Institute (IGTP) and published in Environmental Health Perspectives became .

Long COVID is a heterogeneous disease in which symptoms such as fatigue, shortness of breath, and cognitive problems persist months after COVID-19 infection and cannot be explained by other diagnoses. The true burden of long-COVID remains unclear, but it is estimated that millions of people worldwide are affected. The risk factors have not yet been fully researched, as even people with mild or no symptoms can develop long COVID disease during an acute infection.

“We have previously found that exposure to air pollution is associated with a higher risk of severe COVID-19 disease and lower vaccine response, but there are very few studies on long-term COVID and the environment,” explains Manolis Kogevinas, ISGlobal -Researcher and lead author of the study. In this study, he and his colleagues examined whether air pollution and other environmental exposures such as noise, artificial light at night and green spaces are associated with the risk – or persistence – of long-COVID.

The study followed over 2,800 adults of the COVICAT cohort living in Catalonia, aged 40 to 65, who completed three online questionnaires during the pandemic (2020, 2021, 2023). These surveys collected information on COVID-19 infections, vaccination status, health status, and sociodemographic data. The researchers estimated the residential exposure to noise, particulate matter, ozone, nitrogen dioxide, green spaces and light at night for each participant.

Long COVID risk factors

The analysis showed that one in four people who were infected with COVID-19 had symptoms lasting three months or longer, with 5% having symptoms lasting two years or longer. Women, those with lower levels of education, those with previous chronic illnesses, and those with severe COVID-19 disease were at highest risk of developing long-term COVID. Vaccination, on the other hand, made a positive difference: only 15% of vaccinated participants developed long COVID, compared to 46% of unvaccinated participants.

Air pollution and ongoing long-term COVID

Exposure to fine dust (PM_2.5 and PM₁₀) in the air was associated with a slight increase in the risk of persistent long-COVID (i.e., people who reported long-COVID in 2021 and whose symptoms were still present in the last week before the interview in 2023). The risk of persistent long-term COVID increased linearly with increasing exposure to fine particulate matter in the air. In contrast, factors such as nearby green spaces or traffic noise had little influence on Long-COVID.

The researchers note that while air pollution may not directly lead to long-COVID, it could increase the severity of the initial infection, which in turn increases the risk of long-COVID. “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,” says Apolline Saucy, lead author of the study.

Further research is needed to break down the different types of long-term symptoms and to get a more detailed picture of what role environmental factors might play. “These types of studies are particularly relevant as more people recover from COVID-19 and deal with the possible long-term consequences,” says Kogevinas.

About COVICAT

The COVICAT cohort is a population-based COVID-19 cohort that aims to characterize the health impact of the COVID-19 pandemic on the population in Catalonia, Spain. Basic data comes from the GCAT (Genomes for Life) project of the Germans Trias i Pujol Research Institute (IGTP).

reference

Saucy A, Espinosa A, Iraola-Guzman S, Castaño-Vinyals G, Harding BN, Karachaliou M, Ranzani I, De Cid R, Garcia-Aymerich J, Kogevinas M. Environmental exposures and long-COVID in a prospective population-based study in Catalonia ( COVICAT study). Environmental health perspectives. 2024. https://doi.org/10.1289/EHP15377