The Paris balloon slowly rises above André-Citroën Park (XVe). Like every day, this tourist attraction, which also serves as a tool for measuring air quality, takes curious passengers 150 meters above the ground. The monuments are slowly revealed in the azure blue sky of this Tuesday morning. However, a slight haze still covers the northeast of the capital. “It’s much clearer to the west,” notes one of the passengers.
Could the air be less pure in the east of the capital? That is at least what the new maps unveiled on the occasion of National Air Quality Day, which takes place this Saturday, seem to show. Since 2018, around 500 Parisian electric delivery vehicles have been equipped with Pollutrack sensors that measure the real-time concentration of PM 2.5 (fine particles with a diameter equal to or less than 2.5 microns).
This type of pollution, caused by wood heating, traffic, construction sites, and more, has a strong health impact. A study conducted by the Île-de-France Regional Health Observatory (ORS) and Airparif shows, among other things, that 6,220 deaths in Île-de-France in 2019 were “attributable to prolonged exposure to fine particulate matter PM 2.5 (compared to 10,350 in 2010).”
Based on data collected over the past five years, Jean-Baptiste Renard, research director at the National Center for Scientific Research (CNRS), has been able to establish “a new pollution map.” The Paris territory has been divided into 108 square kilometers where average concentrations of fine particles have been calculated. This method is “complementary” to the maps already produced by Airparif based on modeling, measurement campaigns, and records in six stations in the capital. “There are none on the left bank and in the northeast of Paris,” warns the physicist. “Yet, we can see that it can be heterogeneous from one place to another. Sometimes, certain areas of Paris are five times more polluted than others.”
Unsurprisingly, the entire perimeter of the ring road, in a band at least 1 km wide, is among the most affected areas. “The highest concentrations are in the eastern part between Porte d’Orléans and Porte de Clignancourt, it’s a real catastrophe,” says the fine particles specialist. “And overall, the northeast of Paris is much more polluted, while the southwest is largely spared.”
These disparities are mainly explained by the proximity of heavily trafficked roads but not only. “Contrary to what one might think, the Place de l’Étoile, for example, is not among the most affected areas because these are large thoroughfares that can be ventilated and where pollution can disperse,” explains Jean-Baptiste Renard. On the other hand, the eastern part of the capital has more narrow streets “where polluted air cannot escape.” “We talk about a street canyon when the buildings are twice as high as the width of the street,” adds the researcher.
These are all areas where the threshold set by the World Health Organization (WHO) is regularly exceeded. Since September 2021, the UN agency recommends staying below 15 micrograms per cubic meter daily for PM 2.5. However, between 2018 and 2022, this limit was exceeded an average of 129 days per year in Paris. “But in the vicinity of the ring road, for example, this threshold is exceeded more than 200 days a year, which is equivalent to seven months in a year,” says Jean-Baptiste Renard.
A large part of this mapping aligns with the sociological divides between the wealthier west of the capital and the more devalued east. “This confirms what we already knew with even more precise measurements,” emphasizes Tony Renucci, director of the association Respire. “These disparities confirm that air pollution is also a social issue.”
This issue has been neglected by the government in recent years, according to David Belliard, deputy (EELV) to the Mayor of Paris responsible for transportation. “These are questions that are in clear decline,” regrets the elected official. “We see this in the debates on low-emission zones, where the objectives are constantly being pushed back, or in the opposition to the transformation of the ring road.”
However, air quality has generally improved in Paris and Île-de-France. “In twenty years, the number of kilometers traveled by car has been halved in the capital,” contextualizes Antoine Trouche, engineer at Airparif. “And fine particle levels have dropped by an average of 25% over the past ten years.”
But while all measured pollutants are decreasing, their levels remain above the recommended thresholds for most of them. Not to mention the case of ozone, the only pollutant that continues to increase. “It forms through the combination of polluting gases when it is hot or when there is strong sunlight,” analyzes Antoine Trouche. “So what we have gained in one aspect has been offset by climate change.”
There is also an unknown factor: ultrafine particles, which are equal to or smaller than 1 micron in size. In Paris, they have only been measured permanently since 2019, which does not yet provide sufficient perspective. “The pollution has been displaced,” says Jean-Baptiste Renard. “Recent diesel engines emit fewer large particles, but they have been transformed into smaller particles. And we know that the finer they are, the deeper they penetrate into the body.”
