True or false: does air pollution promote the spread of the coronavirus? – France


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Does the SARS-CoV-2 coronavirus spread over long distances thanks to microparticles that pollute the ambient air, to infect people? An Italian scientific study advances this hypothesis but it remains to be confirmed by other experiments.

In their garden or nose to the window, some confined people have already wondered if a wandering coronavirus could reach their nostrils … A study carried out by scientists from several Italian universities (*) gives some answers to this question. question: according to them, pollution by airborne particles exerts “a promising and stimulating action” for the coronavirus and is linked to the “rates of increase in cases of contagion (…) in certain regions of the north from Italy “. To reach this conclusion, they compared the daily concentrations of PM10 (particles with a diameter of less than 10 microns) collected by the regional environmental protection agencies throughout Italy, from February 10 to 29, with the number of cases infected with the Covid-19 reported by civil protection, taking into account the incubation period. The comparison between the two maps shows an apparent correlation. Sufficient? No. The higher population density in the northern regions could be enough to explain this difference in propagation.

On the left, the map showing the amount of fine particles in the air, between February 10 and 29. On the right, that of the cases of Covid-19, in the days that follow.
On the left, the map showing the amount of fine particles in the air, between February 10 and 29. On the right, that of the cases of Covid-19, in the days that follow. (DR Sima)

Particles carrying viruses

To support their study, the Italian researchers built on results from previous experiments. Results that Professor Isabella Annesi-Maesano, director of research at Inserm, in Paris, knows on the fingertips: “They show that particles of 5 to 10 microns can carry debris, pollens, bacteria . But also viruses, which you can inhale. ” These particles are particularly traveling, capable of achieving Siberia-Amazonia, notes the specialist in allergic and respiratory diseases at the Pierre-Louis Institute of Epidemiology and Public Health. Difficult to imagine an Italian contaminating a Breton by the force of his cough and the winds … But in conditions of close proximity between individuals and in a highly polluted environment, the combined risk would be very important if an infected person got into to cough, according to Isabella Annesi-Maesano.

A request to the prefects to limit spreading

This hypothesis of a transport of the virus by pollution highways remains to be confirmed: other studies will have to be carried out to validate it. Questions remain about the duration of infection of the coronavirus in air, although initial experience has established that it can survive at least three hours in aerosols.

In the meantime, as a precautionary measure, a group of scientists, of which Isabella Annesi-Maesano is a member, asks the prefects “to take urgent measures aimed at drastically limiting emissions linked to agricultural spreading in order to do everything possible to limit the spread of the virus “. In a statement released on Thursday, FDSEA 29 objected to this request.

Containment has made it possible to reduce the level of particles emitted by transport and factories.

“Do not neglect the contribution of pollution”

There remain several certainties concerning the role of pollution in the epidemic, which the authors of the Italian study also note: “Gases and particles damage the mucous membrane of the airways which then lets in external agents, including viruses”, reports Isabella Annesi-Maesano, which increases the risk of exposure. Pollution is also a source of comorbidities such as pulmonary, cardiovascular diseases, diabetes, which are sometimes fatal for people affected by Covid-19… “We must not overlook the contribution of pollution in this epidemic”, she concludes.

* The study was not published in a peer-reviewed journal and therefore was not validated by a college of scientists before publication.

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