Exposure to air pollution increases coronavirus deaths by 15% worldwide, study suggests

Long-term exposure to polluted air has previously been linked to an increase in coronavirus deaths, but new research estimates for the first time the extent to which pollution has increased the proportion of deaths during the pandemic.

The study estimates that about 15 per cent of deaths worldwide from Covid-19 could be attributed to long-term exposure to air pollution.

In Europe the proportion was about 19 per cent, in North America it was 17 per cent, and in east Asia about 27 per cent, while in Australia it was 3 per cent.

The research team, from various institutions in Germany and Cyprus, said these proportions were 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 emissions”.

But they said their research did “not imply a direct cause-effect relationship” between air pollution and Covid-19 mortality –though they conceded it was possible.

Instead, the percentages refer to both the direct and indirect impacts of air pollution, which can aggravate other health conditions which, with the virus, could then lead to fatalities.

The researchers used epidemiological data from previous US and Chinese studies of air pollution and Covid-19, as well as from the Sars outbreak in 2003.

They combined this with satellite data showing global exposure to PM 2.5 particulate matter – air pollution – as well as with information on atmospheric conditions and ground-based pollution monitoring networks.

This allowed them to create a model to calculate the fraction of coronavirus deaths that could be attributable to long-term exposure to PM 2.5.

The results are based on epidemiological data collected up to the third week in June 2020 and the researchers said 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 per cent of coronavirus deaths in the Czech Republic, 27 per cent in China, 26 per cent in Germany, 22 per cent in Switzerland, 21 per cent in Belgium, 19 per cent in The Netherlands, 18 per cent in France, 16 per cent in Sweden, 15 per cent in Italy, 14 per cent in the UK, 12 per cent in Brazil, 11 per cent in Portugal, 8 per cent in the Republic of Ireland, 6 per cent in Israel, 3 per cent in Australia and just 1 per cent in New Zealand.

Professor Jos Lelieveld, of the Max Planck Institute for Chemistry, said: “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.

“However, as an example, in the UK there have been over 44,000 coronavirus deaths and we estimate that the fraction attributable to air pollution is 14 per cent, meaning that more than 6,100 deaths could be attributed to air pollution.

“In the USA, more than 220,000 Covid deaths with a fraction of 18 per cent yields about 40,000 deaths attributable to air pollution.”

Professor Thomas Münzel, from the University Medical Centre of the Johannes Gutenberg University, said: “When people inhale polluted air, the very small polluting particles … migrate from the lungs to the blood and blood vessels, causing inflammation and severe oxidative stress, which is an imbalance between free radicals and oxidants in the body that normally repair damage to cells.

“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.”

He added: “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. If you already have heart disease, then air pollution and coronavirus infection will cause trouble that can lead to heart attacks, heart failure and stroke.”

The scientists also suggested the presence of air pollution in the lungs can aid transmission of the disease.

Professor Lelieveld said: “It's likely that particulate matter plays a role in ‘super-spreading events’ by favouring transmission.”

It does this by stimulating receptors in the lungs which are affected by the coronavirus, making it more likely a person will contract the disease.

He said: “Particulate matter seems to increase the activity of a receptor on cell surfaces, called Ace-2, that is known to be involved in the way Covid-19 infects cells. So we have a double hit: air pollution damages the lungs and increases the activity of Ace-2, which in turn leads to enhanced uptake of the virus by the lungs and probably by the blood vessels and the heart.”

The authors have called for greater action to reduce the emissions which cause air pollution and the climate crisis, saying even small improvements could be beneficial for populations as the pandemic continues.

They said: "Our results suggest the potential for substantial benefits from reducing air pollution exposure, even at relatively low PM2.5 levels… A lesson from our environmental perspective of the Covid-19 pandemic is that the quest for effective policies to reduce anthropogenic emissions, which cause both air pollution and climate change, needs to be accelerated.

“The pandemic ends with the vaccination of the population or with herd immunity through extensive infection of the population. However, there are no vaccines against poor air quality and climate change. The remedy is to mitigate emissions.”

They added: “The transition to a green economy with clean, renewable energy sources will further both environmental and public health locally through improved air quality and globally by limiting climate change.”

The research is published in the journal Cardiovascular Research.