Higher levels of nitrogen dioxide pollutants in the air may be associated with an increased number of deaths from COVID-19, according to a study.
The research, published in the journal Science of the Total Environment, combined satellite data on air pollution and air currents with confirmed deaths related to COVID-19.
It revealed that regions with permanently high levels of pollution have significantly more deaths than other regions, according to the researchers at Martin Luther University Halle-Wittenberg (MLU) in Germany.
Nitrogen dioxide is an air pollutant that damages the human respiratory tract, the researchers said.
For many years it has been known to cause many types of respiratory and cardiovascular diseases in humans, they said.
"Since the novel coronavirus also affects the respiratory tract, it is reasonable to assume that there might be a correlation between air pollution and the number of deaths from COVID-19," said Yaron Ogen from MLU.
The researchers combined three sets of data, including the levels of regional nitrogen dioxide pollution measured by the European Space Agency's (ESA) Sentinel 5P satellite, which continuously monitors air pollution on the Earth.
Based on this data, he produced a global overview for regions with high and prolonged amounts of nitrogen dioxide pollution.
"I looked at the values for January and February of this year, before the corona outbreaks in Europe began," explained Ogen.
He combined this data with data from the US weather agency NOAA on vertical air flows. He explained that if air is in motion, the pollutants near the ground are also more disseminated.
However, if the air tends to stay near the ground, this will also apply to the pollutants in the air, which are then more likely be inhaled by humans in greater amounts and thus lead to health problems, Ogen said.
Using this data, the researcher was able to identify hotspots around the world with high levels of air pollution and simultaneously low levels of air movement.
He then compared these with the data on deaths related to COVID-19, specifically analysing the data from Italy, France, Spain and Germany.
He found that the regions with a high number of deaths also had particularly high levels of nitrogen dioxide and a particularly low amount of vertical air exchange.
"When we look at Northern Italy, the area around Madrid, and Hubei Provence in China, for example, they all have something in common: they are surrounded by mountains. This makes it even more likely that the air in these regions is stable and pollution levels are higher," Ogen said.
The advantage of the analysis, he noted, is that it is based on individual regions and does not only compare countries.
"Even though we can obtain a country's average value for air pollution, this figure could vary greatly from region to region and therefore not be a reliable indicator," said Ogen.
The geoscientist suspects that this persistent air pollution in the affected regions could have led to overall poorer health in the people living there, making them particularly susceptible to the virus.
"However, my research on the topic is only an initial indication that there might be a correlation between the level of air pollution, air movement and the severity of the course of the corona outbreaks," said Ogen.