Reducing speed limit to 50 km/h on Paris' ring road has reportedly led to less traffic, pollution and noise

Workers install a 50 km/h speed limit sign on the Boulevard périphérique, at the Porte d'Ivry, September 30, 2024. THOMAS SAMSON / AFP

One year after the speed limit on the Paris ring road was reduced to 50 kilometers per hour, and seven months after the introduction of the carpool lane, what can be said about the impact of these two measures in terms of traffic and pollution? Two recently published studies have provided some initial answers and paint a generally positive picture, though a comprehensive assessment remains difficult to establish.

The most recent, an evaluation published Wednesday, October 1 by Airparif, the independent body monitoring air quality in the Paris region, highlighted "significant results" and an "improvement in air quality" in areas directly adjacent to the ring road, but urged caution. While Airparif reported an "average decrease in nitrogen dioxide concentrations" (NO₂) – a pollutant mainly emitted by road traffic and known to cause respiratory illnesses – this was an estimate rather than an objective measurement.

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Paris implements controversial 50 km/h ring road speed limit