More research suggests link between air pollution and COVID risk

Matt Woodley

12/01/2022 5:57:34 PM

A new study has added to existing evidence associating air pollution with increased risk of COVID-19 infection.

Bergamo, Italy.
Most of the 3.9 million Europeans residing in areas where air pollution exceeds European limits live in northern Italy.

Long term exposure to ambient air pollution may heighten the risk of COVID-19 infection, according to new research published in Occupational & Environmental Medicine.
The association was strongest for particulate matter, with an average annual rise of 1 µg/m3 linked to a 5% increase in the infection rate – equivalent to an extra 294 cases/100,000 people a year.
Applying seasonal rather than annual averages yielded similar results, and these findings were confirmed in separate analyses that excluded care home residents – which were at a more than 10-fold heightened risk of infection – and further adjusted to account for localised socioeconomic influences and the use of public transport.
Associate Professor Vicki Kotsirilos, a GP who has advised the Victorian Government on the impacts of air pollution, told newsGP the study reinforces the ‘urgent need’ for authorities to address air pollution in Australia, especially in areas of high pollution exposure.
‘It is a good study as it excluded other confounding variables such as seasons,’ she said.
‘The findings add to the overall weight of evidence of previous studies that air pollution increases the risk of respiratory infections.
‘Air pollution from particulate matters – especially the smaller PM 2.5 – can increase the risk of inflammation of the lungs, making the lungs more susceptible to harm to respiratory infections such as COVID-19.
‘The study also identified that other pollutants – PM 10, NO2, NO and Ozone – increase the risk of COVID infection, but not to the same degree.’
While previous research has implicated airborne pollution as a risk factor for COVID-19 infection, study design flaws and data capture only up to mid-2020 have limited the findings, the authors wrote.
To get mitigate these issues, the researchers looked at long-term exposure to airborne pollutants and patterns of COVID-19 infection from the start of the pandemic up until March 2021 among the residents of Varese, Lombardy, which has been Italy’s worst affected region in terms of both cases and deaths.
The observed associations were even more noticeable among older age groups, indicating air pollutants had a stronger effect on the COVID-19 infection rate among 55–64 and 65–74-year-olds.
Associate Professor Kotsirilos said while further research is needed to verify the study’s results, much is already known about how air pollution increases acute lower respiratory tract infections, pneumonia and hospitalisations, even from exposure at low doses below national standards.
‘Air pollution is a known risk factor for a number of chronic diseases such as heart and lung disease, and is associated with increased risk of mortality, while PM 2.5 leads to increases in healthcare use due to lower respiratory tract infections,’ she said.  
‘This research also found that air pollution was also associated with increased risk of drug treatment for diabetes, hypertension, obstructive airways disease and a history of stroke during the study period.’

Associate Professor Vicki Kotsirilos says there is an urgent need for authorities to address air pollution in Australia.

Estimates from the European Union Environmental Agency show that most of the 3.9 million Europeans residing in areas where air pollution exceeds European limits live in northern Italy.
Although the researchers considered various potentially confounding factors, they were not able to account for mobility, social interaction, humidity, temperature and certain underlying conditions, such as mental ill health and kidney disease. As it was an observational study, they were also not able to establish causation.
Nevertheless, the researchers wrote that the findings ‘deserve future generalisation in different contexts’.
‘Our findings provide the first solid empirical evidence for the hypothesised pathway linking long-term exposure to air pollution with the incidence of COVID-19,’ they conclude.
‘Government efforts to further reduce air pollution levels can help to mitigate the public health burden of COVID-19.’
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