The research estimates around 15 per cent of deaths worldwide from Covid-19 could be attributed to exposure to tiny particles of pollution known as particulate matter or PM2.5.
In the UK the figure is around 14 per cent.
Scientists behind the study, published in the journal Cardiovascular Research, said their figures do not imply that air pollution directly caused deaths from Covid-19 – although it is possible.
But it could aggravate other health conditions such as high blood pressure, coronary artery disease, diabetes, asthma and COPD, which lead to a substantially higher risk of death from the virus.
Researchers aimed to assess the proportion of deaths that could be avoided if people were exposed to lower air pollution levels, without emissions from burning fossil fuels and other human-driven activities.
The study used data from previous US and Chinese studies of air pollution and Covid-19 and the Sars outbreak in 2003, as well as data from Italy.
It also drew on satellite data to show global exposure to PM2.5, information on atmospheric conditions and ground-based pollution monitoring networks to create a model to estimate the proportion of Covid-19 deaths attributable to air pollution.
The researchers’ assessment suggests 27 per cent of deaths in East Asia could be attributed to air pollution, 17 per cent in North America 17 per cent and around 19 per cent in Europe overall.
Professor Jos Lelieveld, from the Max Planck Institute for Chemistry in Mainz, Germany, and the Cyprus Institute Nicosia, 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.”
Fellow researcher Professor Thomas Munzel, from Johannes Gutenberg University and the German Centre for Cardiovascular Research in Mainz, said inhaled polluting particles cause inflammation, and damage to arteries.
“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 said.
“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 study also said “it seems likely” that the fine polluting particles prolong the time infectious viruses survive in the air, favouring their transmission.
The researchers said the majority of the particulate matter came from fossil fuels and called for efforts to cut emissions that cause both air pollution and climate change to be accelerated for health and environmental reasons.
Commenting on the study, Professor Anna Hansell, from the University of Leicester, said: “While it is extremely likely that there is a link between air pollution and Covid-19 mortality, it is premature to attempt to precisely quantify it, as here, given the current state of the evidence.
“However, there are plenty of other good reasons to act now to reduce air pollution, which the WHO (World Health Organisation) already links to seven million deaths worldwide per year.”
In the UK, PM2.5 comes from a range of sources including wood burners, road traffic – both from exhaust emissions and brake, tyre and road wear – and industrial, construction and manufacturing processes.