The city of Paris under a cloud of pollution on August 6, 2018. - GERARD JULIEN / AFP

The two months of confinement were only a parenthesis on the pollution front in Paris. This Thursday, the prefecture of Paris placed the capital and its close suburbs in differentiated circulation, because of the forecasts of ozone pollution caused by the high heat expected on the Ile-de-France.

A secondary pollutant which is not emitted directly by human activities. But the latter still play a role. "Ozone results from chemical transformations, under the effect of solar radiation, of primary pollutants such as nitrogen oxides and volatile organic compounds, emitted in particular by road traffic and industrial activities", explains ATMO Grand Est.

Towards a return of NO2 to post-Covid levels

This peak of ozone pollution echoes a study by the Center for Research on Energy and Air Quality (CREA) published this Wednesday. This independent international research organization, based in Finland, has studied the level of nitrogen dioxide (NO2), a very toxic gas emitted mainly by road traffic, in European cities of more than a million. inhabitants, before and after deconfinement, reports Le Monde. To do so, CREA relied on data collected until June 20 by official air quality monitoring networks in Europe. Like Airparif in Ile-de-France.

Result: "Air pollution has already started to converge to post-Covid 19 levels in all the cities taken into account in the study," notes CREA. However, with different rhythms.

Paris, one of Europe's most polluted cities, experienced one of the continent's best improvements in air quality during coronavirus confinement. It's also seen the most abrupt rebound to nearly pre-Covid levels. @ CREACleanAir #pollution #environmenthttps: //

- mike woods (@mawoods) June 24, 2020

+ 118% in Paris, but a rebound to qualify

It is in Paris, precisely, that CREA observes the strongest rebound in the NO2 level (+ 118%), compared to the average of the thirty days of confinement, during which the NO2 concentrations were the lowest. Far behind, we find Brussels (+ 88%) and Milan (+ 73%). And even further Madrid (+ 49%), London and Munich (+ 34%) or Berlin, where the rebound is almost zero. Plus only 4%.

However, the CREA invites us not to overinterpret these differences. If in Paris, the rebound is significant, it is also that the drop in NO2 concentrations had been very strong during confinement. Less 60% compared to the same period of 2017, 2018 and 2019 specifies Le Monde . Against - 33% for London. With Bucharest, Lisbon or Milan, Paris was thus one of the cities where the level of NO2 fell the most, indicates the CREA in its study.

Despite this 118% rebound, Paris is not, today, the most polluted city with NO2 in Europe. The concentration of ozone dioxide remains higher today in Brussels, Milan or Munich.


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