Low temperatures in the morning, great sun and almost zero wind… These weather conditions, which are not conducive to the dispersion of pollutants, should lead to a new episode of fine particle pollution this Wednesday over the whole of Île-de-France.
According to Airparif, the expected levels of PM10 (particles 10 microns thick) in the air should exceed the so-called “information and recommendations” threshold.
But they should stay below the alert threshold from which traffic restrictions can be imposed.
The “information” threshold, the first step in the procedure, is triggered when the levels of fine particles in suspension (which can cause breathing difficulties in certain “audiences”) exceed the bar of 50 µg (micrograms) per cubic meter.
According to forecasts from the regional air quality measurement body, the rates measured on Wednesday could be between 55 and 70 µg / m3 depending on the site.
The most fragile invited to limit outings
These pollution levels will not require the implementation of restrictive measures.
But they justify a series of "health" recommendations for Ile-de-France residents.
The most vulnerable in particular are invited to limit outings, to avoid the approaches to major roads and to ban intense sports activities outdoors.
On the road side, the Paris Police Prefecture should also renew the instructions given to motorists each time the information threshold is exceeded: limit travel, favor less polluting vehicles and carpooling, on major roads reduce its speed of 20 km / h compared to usual speeds. HGV drivers in transit will be invited to bypass the "center" area by the Francilienne.
The occurrence of this type of fine particle pollution episode is far from exceptional in winter.
The previous breach of the information threshold took place on October 14 under the same circumstances.
This new episode could last.
Airparif expects the threshold to be exceeded for at least 24 hours and a “stabilization” of the weather conditions from Thursday.
