Monday , November 30 2020

Infection and air pollution, between good weather and a toxic compound

The Covid-19 pandemic has certainly cleared the polluted skies of large, enclosed metropolises, but experts are especially concerned about the possible toxic link between air pollution and the respiratory virus.

With the spread of anti-pollution measures around the world, traffic restrictions and the economic crisis, numerous studies have sometimes shown spectacular declines in some air pollutants in the US and China. or in Europe. The effect was particularly pronounced for nitrogen dioxide (NO2) and dust. For example, during the spring blockades, Spain saw a 61% decrease in NO2 in the air, France 52% or Italy 48%, according to the European Environment Agency.

While air pollution is believed to be responsible for 7 million premature deaths worldwide each year, some experts say these falls, even if temporary, have certainly saved lives. “In the short term (mainly the acute effects associated with extremely high pollution), we estimate that 2,190 and 24,200 air pollution deaths respectively were avoided in Europe and China during the spring closed periods, respectively,” points out to AFP Paoli Crippy, expert on air quality at the University of Notre Dame in Indiana. “If we consider the long-term effects (chronic respiratory problems, cardiovascular disease, lung cancer …), the number of deaths avoided is much higher,” he assures: 13,600 to 29,500 Europe and 76,400 to 287,000 in China, according to different scenarios.

Same goals

“Unless there is a significant rebound in pollution, which I do not believe, long-term human exposure in Europe will be reduced thanks to a decline in fossil fuel consumption in 2020.” and that will affect health risks in the long term, ”adds Lauri Myllyvirta of the Center for Energy and Clean Air Research (CREA), which estimates the number of deaths avoided thanks to the spring closure at 11,000 in Europe.

If these potential lives saved are at least one positive side of the pandemic, which has so far killed 1.3 million people, then this experience is, above all, for advocates of healthy air, further proof of the need to combat this harmful pollution. Especially as studies are accumulating to highlight the likely adverse effects of air pollution on Covid-19, its severity and even mortality. “The results have been replicated in such different contexts and countries that I think the combined evidence is starting to be strong,” says Lauri Myllyvirta.

For memory

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According to a study published in late October in Cardiovascular Research, long-term prior exposure to PM2.5 fine particles increased Covid-19-related mortality by 15% worldwide, with regional variations (27% in East Asia, 19% in Europe, 17% in North America). This virus and PM2.5, already accused of contributing to cardiovascular and pulmonary disease, attack the same targets. “They are responsible for the same thing: pneumonia, secondary pneumonia, high blood pressure, as well as myocardial infarction and heart failure,” explains Dr. Thomas Münzel, cardiologist at the Medical University of Mainz. who participated in the study. So if you have pre-existing cardiovascular disease, “you are at particular risk of developing Covid,” he adds.

“Double Warning”

Analyzes conducted in over 3,000 counties in the United States showed that an increase in average fine particle concentration by 1 microgram / m3 corresponds to an 11% increase in coronavirus-related mortality.

In their study, published in early November in Science Advances, however, the authors warn against overinterpreting these statistics, stressing the need for further work. Regarding the impact of exposure to air pollution during disease, it is unknown. “I am sure the short-term reduction of air pollution has an impact, although we do not have data at the moment,” comments Dr. Münzel.

Clues are also starting to emerge regarding the mechanism of interaction, in particular the role of the ACE-2 receptor that facilitates entry of the SARS-CoV-2 coronavirus into cells.

Role described in Spring in the Journal of Infection as the “double-hit hypothesis”: the fine particles would damage this receptor, allowing more virus to get into the infected patient, which could be made worse by chronic NO2 exposure which weakens the lungs. A situation that would be of particular concern in some polluted countries that are undergoing a new virus attack, such as India. With the advent of winter, the “contamination season,” “this is obviously a great cause for concern for Covid patients,” warns Lauri Myllyvirta.

The Covid-19 pandemic has certainly cleared the polluted skies of large, enclosed metropolises, but experts are especially concerned about the possible toxic link between air pollution and the respiratory virus.

With the spread of deterrents around the world, traffic restrictions and the economic crisis …

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