- The new air index, introduced in each region, now takes into account PM 2.5, these very fine particles, which are particularly harmful for health.
This change in scale is likely to be noticed in Hauts-de-France, very concerned by pollution with very fine particles.
Nevertheless, the regulations on pollution peaks remain the same.
It was a pollution that went unnoticed. From this Monday, the new air index, introduced in each region, now takes into account PM 2.5 , these particles invisible to the naked eye (less than 2.5 micrometers), particularly harmful to health. This change of scale is likely to be noticed in
les Hauts-de- France , but paradoxically, it will not change anything regarding pollution alert measures.
Less reported particles so far
Until then, the Atmo site, which measures regional pollution levels on a daily basis, was based on four pollutants: sulfur dioxide, nitrogen dioxide, ozone and fine particles PM 10, the diameter of which is less than micrometers (µm). From now on, PM 2.5 (less than 2.5 µm) will also be taken into account in the daily calculations.
These very fine particles are more harmful because they can slip further into the body. Hence the recommendations of the World Health Organization (WHO) not to exceed three days per year, above the threshold of 25 µg in the atmosphere. However, in the Lille metropolis, the threshold has been exceeded a About fifty days per year without this data being taken into account. This will now be the case, automatically causing the indices to plunge downwards. Hauts-de-France particularly concerned
“We should therefore not be surprised to see the air quality indices deteriorate while the level of pollution will be the same ”, specifies Atmo. Indeed, the Hauts-de-France region, and especially the metropolis of Lille, are particularly affected by the presence of PM 2.5.
During a study conducted in 310, Atmo had noticed that these particles were more related to heating (41%) that the PM (27%). “However, the weather is causing homes to heat up more than in other regions,” notes Atmo. There is also the fact that many buildings continue to suffer from insulation problems. Reducing these particles is therefore a puzzle.
Still no regulatory threshold 
But measuring pollution does not mean “taking action”. Thus, unlike PM , there is still no regulatory threshold for these PM2.5. This contradiction means that, despite poor air quality due to PM 2.5, there will not be more
pollution peaks
triggered by the prefecture
The air index has adapted to European standards, not legislation French. For individuals, this new air index will therefore not be synonymous with more traffic restrictions. Until further notice.