This is a warning for the pollution peaks expected in the Paris region these days: fine particles of natural or anthropogenic origin would carry viruses, thus promoting their dispersion. The Covid-19 pandemic provides new knowledge about this unforeseen effect of air pollution.
There are still doubts but the body of evidence is tightening. Fine particles of less than 10 microns (PM10) and less than 2.5 microns (PM2.5) could well serve as a mode of transport for viruses in general, the current SARS-CoV-2 in particular. This is what an interdisciplinary team from the University of Geneva (UNIGE) and the Swiss Federal Institute of Technology in Zurich. The high concentrations of these aerosols in the air can modulate or even amplify the waves of contamination of the SARS-CoV-2 coronavirus by serving as a vector of dissemination, according to their results which have just been published in Earth systems and Environment.
Climatologists Mario Rohrer and Markus Stoffel and epidemiologist Antoine Flahaut start from several observations of a close link between episodes of pollution and sudden outbreaks of contamination. On February 23, 2020, a major sandstorm from the Sahara affected the Canary Islands. The next day, a tourist from a high-risk region in northern Italy fell ill. He tested positive for Covid-19 at the local hospital. "In the following days, several other tourists from different hotels also contracted the disease and it is believed that the particles spread the virus as they already do with the spores of the microscopic fungus Aspergillus", says Mario Rohrer. The presence of these spores has already been noted on numerous occasions and has been the subject of numerous scientific studies which also show that these biological particles also have a deleterious effect on human health. Similarly, studies conducted in Beijing (China) in 2016 and in Jinan province in 2019 showed that fine particles from human activity this time could spread the flu virus.
Disturbing coincidences between pollution peaks and hospitalizations
So why not the coronavirus? Because researchers have found two other disturbing cases of a correlation between pollution peaks and a sudden spread of the coronavirus. Around February 24, 2020, the canton of Ticino in Switzerland experienced a sharp increase in PM2.5 pollution due to a thermal inversion phenomenon, with ground temperatures that day being 0.3 ° C in the bottom of the valleys compared to 12°C on the tops of the slopes. In the following days, the region experienced a sharp increase in hospitalizations, further aggravated by the concentration of 150,000 people who came to celebrate the carnival. At the same time, in Zurich, 178 kilometers away, there was neither a pollution peak nor an increase in hospitalizations due to Covid-19.
Finally, the last examples are those of the metropolises of London and Paris.
Full publication (Fr) : Sciences et Avenir Published on November, 2020