The objective was to avoid a "dieselgate" for the 10,000 buses and coaches in Ile-de-France.
In 2018, Ile-de-France Mobilités and Airparif therefore launched a vast campaign to control the polluting emissions of these vehicles which transport Ile-de-France residents on a daily basis on the RATP network as well as on Optile buses in the outer suburbs.
The results of "the first study of this magnitude in the world", according to Valérie Pécresse, president of IDFM, were unveiled this Thursday morning.
Nitrogen dioxide (NOx), carbon dioxide (CO and CO2) or fine particles (PM) were measured, using sensors installed on 28 different buses (diesel, hybrid or natural gas), which actually circulated and transported from the public.
It even required removing rear seats to install these advanced sensors.
In all, 30 million measurements were taken and analyzed over 1,600 regular trips.
Unsurprisingly, the oldest buses, the Euro IV diesels, are the ones that emit the most polluting gases.
For example, for NOx, emissions are four times lower for Euro VI diesel buses approved after 2014 than for Euro IV vehicles approved eight years earlier.
Hybrid Euro VI buses emit ten times less than diesel Euro IVs, and natural gas buses 30 times less.
The slower it is, the more polluting it is
The study also notes that for Euro IV buses, the decrease in average speed from 20 km / h to 8 km / h leads to a doubling of NOx emissions and a 40% increase in CO2 emissions.
This influence of speed is however much less for newer buses.
"Where there is congestion, Euro IVs are extremely polluting", summarized Valérie Pécresse, pointing to the traffic in Paris.
"We must ensure that there is a good cohabitation between bicycle and bus, because the effect of coronapists can be pollution."
Especially since the deployment of clean buses in Paris is not easy.
"We have to try not to put Euro IVs in the most congested areas and that depends on our deployment of bus depots, because if we do not have a clean bus depot (electric or biogas) in Intramural Paris we cannot put anything other than diesel buses, ”added Valérie Pécresse.
Only 27% of clean buses
The fleet of 10,000 buses and coaches in Ile-de-France is made up of 45% Euro IV buses or similar technology, 29% Euro VI buses and 27% hybrid, CNG or electric buses.
Replacing more than 2,000 buses between 2014 and 2020 reduced annual NOx, exhaust particulate (PN) emissions by around a third and CO2 emissions from buses by less than 5%, according to IDFM.
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The goal is still "the total end of diesel buses for urban areas in 2025 and for rural areas in 2029".
The replacement of buses and the adaptation of their operational centers represent a program of 4 billion by 2030. A new order for 1000 electric or biogas buses for the RATP, and 160 for the inner suburbs, is planned in a few days by IDFM.
New study on air quality in the metro
In addition to bus pollution, Valérie Pécresse returned to the air pollution in the metro, following the controversy this Wednesday between the association Respire and RATP.
Respire claimed that the RATP data did not reflect the actual levels of pollution in the metro, which the public operator disputes.
To settle the debate, the president of IDFM yesterday commissioned Airparif for a new study on the air quality in the metro.
"We are taking the recipe that worked for buses, we called on Airparif to conduct an independent study," announced Valérie Pécresse, who is also counting on other long-term measures, mainly the complete renewal of subways here. to 2033. The switch from mechanical braking to electrostatic braking for more than 1000 trainsets will reduce the particles emitted during braking, according to IDFM.
In addition, reminds the Region, since June 2019, several companies have been testing air pollution control systems in the metro and RER.
A call for projects had indeed been launched to experiment with solutions.
Five projects had been selected.
And some have given initial results.
The “positive ionization” solution tested at the Foch station (RER C) by Air Liquide and Alexandre Dumas (Line 2) by Suez makes it possible to “capture 20% of particles in the immediate vicinity” assures Jean-Philippe Dugoin-Clément, vice president in charge of sustainable development in the Region.
"But that means it has to be deployed in several places on the quay."
Two caissons cover only 50% of the quay.
The elected representative expects even more from the experimentation developed in partnership between SNCF and Tallano.
This system plans to install a sort of vacuum cleaner just behind the brakes and capture the particles emitted at the source: “There we were able to suck 2/3 of the particles.
Which gives real prospects ”.