Air pollution linked to increased risk of COVID-19

An observational study of young adults in Stockholm, Sweden showed that residential exposure to ambient air pollutants is associated with a higher risk of SARS-CoV-2 infection. The study was conducted by researchers from Karolinska Institutet and published in JAMA Network is open.

Since pollutants in outdoor air can increase the risk of respiratory infections such as influenza and SARS, the COVID-19 pandemic has raised concerns that they can also contribute to the risk of SARS-CoV-2 infection. Studies have also shown that areas with poor air quality have more cases of COVID-19.

Researchers at Karolinska Institutet have now studied this more closely by examining the link between estimated exposure to air pollutants at home addresses and positive PCR tests for SARS-CoV-2 in young adults in Stockholm, Sweden.

The results show that exposure to certain traffic-related air pollutants is associated with a greater likelihood of a positive test.

says Olena Gruzieva, associate professor at Karolinska Institutet’s Institute of Environmental Medicine and one of the study’s latest authors.

The study is based on the population-based BAMSE project, which has regularly followed more than 4,000 participants in Stockholm from birth. By correlating this data with the National Registry of Infectious Diseases (SmiNet), researchers identified 425 individuals who tested positive for SARS-CoV-2 (PCR testing) between May 2020 and the end of March 2021. The average age of the participants was 26, and 54 percent were women. .

Daily outdoor concentrations of various air pollutants at participants’ home addresses were estimated using dispersal models. The pollutants were particulate matter less than 10 micrometers in diameter (PM10) and 2.5 micrometers (PM2.5), carbon black and nitrogen oxides.

The researchers studied the relationship between infection and exposure to air pollutants on the days before a positive PCR test, on the day of the test and on the days of subsequent observation. Each participant acted as his or her own controller on these different occasions.

The results show associations between infection risk and exposure to PM10 and PM2.5 two days before a positive test and exposure to carbon black one day before. They found no link between infection risk and nitrogen oxides.

The increase in risk by volume was about seven percent for each increase in particulate exposure equivalent to the quartile, i.e. between the first (25%) and third quartile (75%) of the estimated particle concentrations.

Eric Millen, MD, professor of pediatrics in the Department of Medical Sciences and Education, Södersjukhuset, Karolinska Institutet, BAMSE project lead and joint recent author of the study.

The observed association was not affected by sex, smoking, weight gain, or asthma.

The researchers note that the results may be influenced by willingness to take the PCR test and the fact that many young people have no or only mild symptoms after infection. The study also cannot rule out the possibility that confounding factors varying over time also affected the results.

Researchers are now examining the relationship between air pollutants and post-COVID symptoms in young adults.

The paper’s first author is Zhebin Yu, a postdoctoral researcher in Olena Gruzieva’s group. The study was funded by Forte, the Swedish Research Council, the Swedish Heart and Lung Foundation and the Stockholm Region. The authors did not report any conflict of interest.

the post: “Short-Term Exposure to Air Pollution and SARS-CoV-2 Infection Among Young People in Sweden” Zybin Yu, Tom Belander, Anna Bergstrom, Joachim Dillner, Christina Enroth, Magnus Engardt, Antonius Goergelis, Inger Koll, Peter Ljungmann, Goran Bershagen, Massimo Stafogia Eric Mellin, Olina Gruzeeva and the BAMSE COVID-19 Study, JAMA Network is open, Online. 20 Apr 2022, doi: 10.1001/jamanetworkopen.2022.8109.

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