New research has said that long-term exposure to air pollution contributed roughly 15 percent to COVID-19 deaths worldwide and 19 percent in Europe.

Czechia, Poland, Austria and Germany were among the countries with the highest percentages of COVID-19 mortality attributed to air pollution.

The study, published in the journal Cardiovascular Research by experts from Germany and Cyprus, used satellite and ground-based data of global exposure to fine particulates, along with an atmospheric chemistry model, combined with data from the U.S. and China relating to air pollution, COVID-19 and SARS-CoV-1, to measure the role of air pollution in the COVID-19 mortality rate.

Data showed that East Asia had the highest percentage of COVID-19 deaths that could be attributed to air pollution and its effects on human health, at 27 percent, while in North America the proportion was slightly lower than that in Europe, at 17 percent.

According to the researchers, exposure to air pollution aggravated conditions that led to an increased risk of death from infection by SARS-CoV-2, the virus that causes COVID-19, representing a "potentially avoidable, excess mortality."

"Considering the cardiovascular and respiratory health impacts of air pollution, the relationship to COVID-19 mortality is not unexpected," the authors said.

"The mortality from COVID-19 depends on comorbidities, including conditions that increase cardiovascular risks such as arterial hypertension, diabetes mellitus, obesity, and established coronary artery disease, as well as respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD), being similar to those that are influenced by air pollution," they explained.

Europe's air pollution

While the study found that East Asia was the region faring the worst in terms of COVID-19 mortality attributed to air pollution, on a country-level, European countries Czechia and Poland had the highest percentages, 29 percent and 28 percent respectively, coming in above China and North Korea, both at 27 percent.

Other countries in Europe with at least a quarter of COVID-19 deaths attributed to air pollution are Slovakia (27 percent), Austria (26 percent), Belarus (26 percent), Germany (26 percent), Hungary (25 percent) and Luxembourg (25 percent).

In parts of Europe where deaths were particularly high, researchers said there was also evidence of high levels of fine particulate matter, or pollution.

"In Italy, it was found that the high pollution concentrations that are typical for the Po valley, especially in the Lombardy region of which Milan is the capital, were associated with a high mortality rate."

The study's authors explained that while the limited data do not allow conclusions about cause-effect relationships, i.e. that air pollution itself was killing people with COVID-19, they would not rule it out, as "the biological mechanisms of air pollution-related disorders, acting as comorbidities in COVID-19, are well documented."

"Furthermore, it seems likely that fine particulates prolong the atmospheric lifetime of infectious viruses, thus favoring transmission," the authors added.

The scientists also hope that this data will help inform policy decisions, as it suggests air pollution is an important co-factor increasing the risk of death from COVID-19. "This provides extra motivation for combining ambitious policies to reduce air pollution with measures to control the transmission of COVID-19."

The authors also highlight that if measures are not taken soon, air pollution will continue to kill large numbers of people even in a post-pandemic world. "The global loss of life expectancy from long-term exposure to ambient air pollution exceeds that of infectious diseases, and is comparable with that of tobacco smoking," they explained.

"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," the authors added.