Air pollution linked to higher risk of Covid-19 in young adults

Exposure to air pollution has been linked to an increased risk of Covid-19 infection in an observational study of young adults in Sweden.

Since pollutants in the outdoor air can increase the risk of respiratory infections such as influenza and SARS, the Covid-19 pandemic aroused concerns that they could also contribute to the risk of SARS-CoV-2 infection.

Previous studies have found that areas of poor air quality have more cases of Covid-19.

Researchers at the Karolinska Institutet studied this more closely, examining the link between estimated exposure to air pollutants at home addresses and positive PCR tests for Covid-19 in young adults in Stockholm.

The results show that exposure to certain traffic-related air pollutants is associated with a greater likelihood of testing positive for Covid-19.

‘Our results add to the growing body of evidence that air pollution has a part to play in COVID-19 and support the potential benefit of improving air quality,’ says Olena Gruzieva, Associate Professor at the Institute of Environmental Medicine at Karolinska Institutet and one of the study’s last authors.

The study measured daily outdoor concentrations of different air pollutants, including PM10, PM2.5, black carbon and nitrogen oxides, using dispersion models.

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

The increase in risk was of an order of magnitude around 7% per particle exposure increase. The observed association was not influenced by gender, smoking, weight or asthma.

‘Seven per cent doesn’t sound much, but given that everyone is more or less exposed to air pollutants, the association may be of great significance to public health,’ says Erik Melén, Professor of Paediatrics at the Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, BAMSE project leader and the study’s joint last author.

Photo by Mufid Majnun