Air pollution can increase the risk of positive COVID-19 testing
Air pollution can increase the risk of positive COVID-19 testing

Air pollution can increase the risk of positive COVID-19 testing

An observation JAMA Network Open examination today, involving young adults in Sweden, suggests that short-term exposure to even relatively low levels of air pollution is associated with a higher risk of later testing positive for COVID-19, probably by exacerbating the symptoms in those who are already infected.

A team led by researchers from Karolinska Institutet in Stockholm linked the potential child, allergy milieu, Stockholm, epidemiological birth cohort (after 4,089 infants born from 1994 to 1996) to the Swedish National Infectious Disease Register to identify positive COVID-19 test results from 5 May 2020 to 31 March 2021.

From August to June 2021, participants were invited to complete online questionnaires and undergo a clinical trial. The median age was 25.6 years.

A total of 425 participants were diagnosed with COVID-19. The investigators used dispersion models to estimate daily levels of air pollution consisting of particles, black carbon and nitrogen oxides at home addresses. The primary source of air pollution in Stockholm is road traffic, the researchers noted.

The results may have “major implications for public health”

Each interquartile range increases in short-term exposure to small diameter (2.5 micrometers [μm] or less) particles (inhalable microscopic solids or liquids) were associated with a relative increase of 6.8% in positive COVID-19 test results over the next 2 days.

Exposure to larger diameter particles (10 μm or less) was associated with an increase of 6.9% in positive tests within 2 days, while exposure to black carbon was associated with an increase of 5.8% the next day. No such compound was found for nitrogen oxides. The results did not change when considering sex, smoking, asthma, obesity, or COVID-19 respiratory symptoms.

“Seven percent do not sound [like] much, but considering that everyone is more or less exposed to air pollutants, the association can have great significance for public health, “said joint senior author Erik Melén, MD, PhD, in a Karolinska Institutet news release.

The study authors said that the results, when taken together with the results of previous studies, suggest that short-term exposure to air pollution has a role in exacerbating COVID-19 symptoms in those who are already infected, rather than in helping with viral dispersion.

“Short-term exposure to air pollution can affect airway inflammation and oxidative stress, whereas absorbed air pollutants can cause deep lung irritation and immune modulation of the host’s response to infection, possibly exacerbating the severity of existing infection,” they wrote. “These results support the broad public health benefits of reducing ambient air pollution.”

The researchers warned that the results may have been influenced by the willingness to take a COVID-19 test, the asymptomatic or mild nature of many infections, and time-varying confusing factors.

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