He had not hesitated to draw this figure on the occasion of his vows. The environmental mayor Pierre Hurmic (EELV) had advanced a 20% drop in pollution on the Bordeaux boulevards since the establishment of a lane for soft transport (buses and bicycles) in 2021. In the light of the study carried out by the Atmo Nouvelle-Aquitaine air quality observatory and to which the mayor of Bordeaux refers, we see that the drop in concentrations of nitrogen dioxide, the pollutant tracer of road traffic, is in fact even higher, around 30%, if we compare the measurements taken in the winter of 2018/2019 and those recorded between February 16 and April 13, 2022.
“A big hit of 2022”
“The developments of the metropolis and the town hall have caused a drop in traffic, which has contributed to this drop, comments Emilie Palka, the study engineer who wrote the study “Air quality around Bordeaux boulevards and other main roads in the metropolis”, published in September 2022. But the car fleet has also been renewed over the years and there are more and more less polluting vehicles, this also plays a role. The drop is also to be qualified with regard to the weather conditions which can influence the results and which cannot be guaranteed to be exactly the same during the two measurement campaigns.
From the point of view of the observatory it is “a fairly significant drop” and from the point of view of the Bordeaux elected official, whose group for the municipal elections was called “Bordeaux breathe”, it is a small political victory. “A big hit in 2022 was the boulevards, with +75% cyclists and I don’t think there is a carryover elsewhere,” explained Pierre Hurmic. It’s not a spontaneous generation of cyclists, it’s people who, before, took the car and changed their mobility, and that’s what we want to provoke. »
He recalls that there was an outcry at the start and that it was explained to him that it was a road route, whether he wanted it or not. “But it works”, he slips with satisfaction. There had been no consultation before the installation of the cycle paths but, under tactical town planning, a reversal was possible with the stroke of a brush. Far from a coaster, the idea is rather to replicate this type of cycling infrastructure.
Other pollutants to watch out for
It should be noted that while the regulatory emission thresholds set by the World Health Organization (WHO) have not been exceeded, the recommended thresholds, updated in 2021 and made more restrictive, have been exceeded. at all the sites studied. While nitrogen dioxide concentrations are on the decline, those of suspended particles (PM10) are stable over the period studied. They come from different sources, less obvious to trace: mostly (42%) from the residential/tertiary sector (heating), 36% from transport and 20% from industry.
The Atmo study shows an overall decrease in nitrogen dioxide pollution at all the points studied (Grand Parc fixed station, Port de la lune mobile station, in addition to the fixed station on the boulevards) . It must be said that over the past three years, the number of cyclists has increased by 40% on the intraboulevard sector.