Air pollution is the most urgent environmental health risk in the world. More than 90% of the planet breathes unhealthy air, leading to seven million premature deaths per year and billions of dollars in costs for health services.

The cities and regions most affected by air pollution, mainly located in China and India, are also exposed to a larger risk from coronavirus, a group of experts grouped under the European Public Health Alliance (EPHA) warned.

The polluted air that leads to diseases such as diabetes may also cause a higher overall number of coronavirus cases, EPHA said, claiming that the level of emissions from diesel cars in many cities was still “dangerous” despite the pandemic.

“Patients with chronic lung and heart conditions caused or worsened by long-term exposure to air pollution are less able to fight off lung infections and more likely to die,” EPS member Sara De Matteis said. “This is likely also the case for COVID-19.”

There is no proven link between coronavirus mortality and air pollution yet. But the EPHA mentioned a 2013 study that looked into the outbreak of SARS, which is related to the coronavirus, and found that victims of the virus were 84% more likely to die if they lived in areas with moderate air pollution.

With over 8.000 cases, SARS killed 774 people between 2002 and 2003, with most infected located in China. The mortality information of COVID-19 is so far incomplete but the preliminary figures indicate that most of the patients that died were elderly or had pre-existing chronic conditions.

EPHA said the northern region of Italy is not only the center of the coronavirus outbreak in Europe, but also a hotspot of air pollution in the continent. There was a significant drop in pollution levels in the region since the outbreak, according to satellite images. A similar effect was seen in China, one of the countries most affected by air pollution. Satellites detected a “significant” drop in nitrogen dioxide (NO2) levels in China’s airspace. The reduction can be linked, at least partially, to the economic slowdown following the coronavirus outbreak.

While the air might be clearing in Europe, the “damage had already been done to human health and the ability to fight off infection,” said EPHA Acting Secretary-General Sascha Marschang. Governments should have tackled chronic air pollution long ago, but have prioritized the economy over health, he added.

A recent study claimed the world is facing a “pandemic of air pollution”, which shortens life expectancy by almost three years — more than tobacco, AIDS, wars, or diseases such as malaria. East Asia and Africa were found to be the most affected region.