Long-term exposure to air pollution may increase Covid-19 risk, claims study
Long term exposure to ambient air pollution is likely to worsen the risk of COVID-19 infection, claims recent research whose findings were published in the journal 'Occupational and Environmental Medicine'.
The link was strongest for particulate matter, with an average annual raise of 1 ug/m3 associated with a 5% increase in the infection rate. According to the results, which focus on the residents of one Northern Italian city, this amounts to an additional 294 cases/100,000 people per year.
Researchers say that even though further research is needed to determine cause and effect, the findings should reinforce efforts to cut air pollution.
The coronavirus pandemic has wreaked havoc on northern Italy, with Lombardy being the worst-affected region in terms of both cases and deaths. Different testing methodologies and demographics have been suggested as possible explanations.
However, according to estimates from the European Union Environmental Agency, Northern Italy is home to the majority of the 3.9 million Europeans who live in places where air pollution exceeds European limits.
According to the researchers, a recent study has implicated airborne pollution as a risk factor for Covid-19 infection, but study design flaws and data capture only up to mid-2020 have limited the findings.
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To get around these limitations, they looked at long term exposure to airborne pollutants and patterns of Covid-19 infection from the beginning of the pandemic to March 2021 among the residents of Varese, the eighth-largest city in Lombardy.
As of 31 December 2017, among the 81,543 residents, more than 97% were successfully linked to the 2018 annual average exposure levels for the main air pollutants, based on home address.
From the end of 2019 to the end of March 2021, data on Covid-19 infection, hospital discharge, and outpatient medicine prescriptions were collected for 62,848 adults who had not yet been infected with SARS-CoV-2.
By the end of March 2021, only 3.5 percent of the population in the entire region had been properly vaccinated, according to official figures.
Over a 40-kilometre-wide area, estimates of annual and seasonal average levels of five airborne pollutants were available for 2018 - particulate matter (PM2.5, PM10), nitrogen dioxide (NO2), nitric oxide (NO), and ozone (O3).
The study included over 4,408 new Covid-19 cases that were recorded between February 25, 2020, and March 13, 2021. This amounts to 6,005 cases per 100,000 population per year.
The density of the population was not linked to an increased risk of infection. However, staying in a residential care home was related to a 10-fold increased risk of infection.
A history of stroke, drug treatment for diabetes, high blood pressure, and obstructive airway disease, were all linked to a 17 percent, 12 percent, 17 percent, and 29 percent increased risk, respectively.
According to the researchers, the observed associations were even more evident among older age groups, indicating a higher effect of pollutants on the Covid-19 infection rate among 55-64 and 65-74-year-olds.
Because this is an observational study, it is impossible to determine the cause. Moreover, despite considering a variety of potentially important aspects, the researchers were unable to account for mobility, social interaction, humidity, temperature, and some underlying ailments such as mental illness and kidney disease.
Long-term air pollution exposure increases the risk of respiratory and cardiovascular diseases by causing chronic inflammation and a compromised immune system. According to the researchers, these identical processes may be involved in the association between air pollution and greater Covid-19 infection rates.
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