Study finds that air pollution has caused 15% of covid-19 deaths worldwide

As winter sets in and northern India enters the most polluted months of the year, the concerns about how air pollution can aggravate the current covid-19 situation are rising.

The link between covid-19 and air pollution has long been established, with multiple scientific papers claiming that polluted air can increase the transmissibility of the virus.

And now a study has brought forth yet another shocking connection: about 15% of deaths worldwide from covid-19 could be linked to long-term exposure to air pollution.

Researchers, including those from Max Planck Institute for Chemistry in Germany, found that in Europe the proportion of covid-19 deaths linked to air pollution was about 19%, in North America it was 17%, and in East Asia about 27%.

The study, published in the journal Cardiovascular Research, is the first to estimate the proportion of deaths from the coronavirus that could be attributed to the exacerbating effects of air pollution for every country in the world.

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The team noted that these proportions are an estimate of the fraction of covid-19 deaths that could be avoided if the population were exposed to lower counterfactual air pollution levels without fossil fuel-related and other anthropogenic (caused by humans) emissions.

This attributable fraction does not imply a direct cause and effect relationship between air pollution and covid-19 mortality, the researchers said.

Instead it refers to the fact that air pollution can aggravate co-morbidities, and other health conditions, that could lead to fatal health outcomes of the virus infection, they said.

This is how the study was conducted

The researchers used epidemiological data from previous US and Chinese studies of air pollution and covid-19 and the SARS outbreak in 2003, supported by additional data from Italy.

They combined this with satellite data showing global exposure to polluting fine particles known as ‘particulate matter’ that are less than or equal to 2.5 microns in diameter (known as PM2.5), information on atmospheric conditions and ground-based pollution monitoring networks.

The researchers created a model to calculate the fraction of coronavirus deaths that could be attributable to long-term exposure to PM2.5. The results are based on epidemiological data collected up to third week in June 2020 and the researchers say a comprehensive evaluation will need to follow after the pandemic has subsided.

Estimates for individual countries show, for example, that air pollution contributed to 29% of coronavirus deaths in the Czech Republic, 27% in China, 26% in Germany, 22% in Switzerland, and 21% in Belgium.

“Since the numbers of deaths from covid-19 are increasing all the time, it’s not possible to give exact or final numbers of covid-19 deaths per country that can be attributed to air pollution,” said Professor Jos Lelieveld from the Max Planck Institute for Chemistry.

Here’s how air pollution can make covid-19 cases worse

Professor Thomas Munzel from the Johannes Gutenberg University in Germany noted that when people inhale polluted air, the very small polluting particles, PM2.5, migrate from the lungs to the blood and blood vessels. En route, they cause inflammation and severe oxidative stress, which is an imbalance between free radicals and oxidants in the body that normally repair damage to cells.

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“This causes damage to the inner lining of arteries, the endothelium, and leads to the narrowing and stiffening of the arteries. The covid-19 virus also enters the body via the lungs, causing similar damage to blood vessels, and it is now considered to be an endothelial disease,” Munzel said.

“If both long-term exposure to air pollution and infection with the covid-19 virus come together then we have an additive adverse effect on health, particularly with respect to the heart and blood vessels, which leads to greater vulnerability and less resilience to covid-19,” he concluded.

(With inputs from PTI)