Illustration of the Rennes ring road, here from the Porte d'Angers.

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C. Allain / APEI / 20 Minutes

Four years after a major study on speed reduction on the ring road, Rennes will once again examine its pollution around its ring road.

It is the AirBreizh institute, responsible for monitoring air quality in Brittany, which has just announced it.

Unlike 2016, it is above all the fine particles that will be closely monitored this time.

The first analyzes of these results will be known in spring 2021.

The abandonment of the 70 km / h limit on the Rennes ring road caused a stir in 2016. Angry at having to slow down, motorists applauded the decision to standardize the speed at 90 km / h on the four lanes encircling the Breton capital.

Because if the reduction of the speed from 110 to 90 km / h on the East and North part had made it possible to reduce nitrogen dioxide emissions by 30 to 40%, the effect was neutral, even negative on parts limited to 70 km / h.

Life expectancy reduced by two years in twenty years

Voices were then raised to criticize the lack of study of the impact on fine particles.

Distributed by heating, particularly wood, diesel vehicles and agriculture, these particles enter our lungs and can cause significant damage to the respiratory tract.

According to the University of Chicago, life expectancy has been reduced by two years worldwide because of this pollution.

Conducted in summer, the impact study piloted by AirBreizh had not made it possible to extract consistent data in Rennes.

This new study should make it possible to "determine the share of road traffic in the particle concentrations measured near the roads" but also to assess "their distance of influence" around these axes, according to AirBreizh.

Funded by DREAL and Rennes Métropole, this survey begins this week and will last for a month.

The period of September was chosen because of the low use of heating, which will avoid skewing the data.

Continuous analyzes and microsensors have been installed between Porte de Nantes and Porte de Saint-Nazaire.

The results are expected in the spring.

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Environment: Fine particle pollution reduced life expectancy by two years

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  • Nathalie Appéré

  • Ring road

  • Fine particles

  • Air pollution

  • Diesel

  • Automotive

  • Pollution

  • Reindeer

  • Planet