Pollutionwatch: how does World Car-free Day affect emissions? | The Guardian

Though air quality appeared to improve, measuring the precise impact of car-less days is difficult

Gary FullerThu 26 Sep 2019 21.30 BST
Last Sunday peace and tranquillity descended on city centres across the world as many went car-free for the day.

This annual event started in the UK, in Bath, in 1994 with a road closure and street party for the Environmental Transport Association’s Green Transport Week. In 1997 it spread to France with En Ville Sans Ma Voiture (In Town Without My Car) in La Rochelle, and by 2007 it spanned 2,000 cities in 35 countries.

The event is not just about air pollution. It is primarily designed to show streets as places for public transport, walking and cycling as well as social spaces. It also tries to show how much better urban life can be without cars.

Working out the environmental impact of a car-free day is difficult because air pollution is influenced by the weather as well as by emissions. In Paris this year, nitrogen dioxide was estimated to be 7% less compared with the average Sunday. In one street there was a 45% decrease.

In London, where 17 miles (27km) of roads were closed, a temporary air-quality monitoring site in Regent Street measured a decrease of 60% compared with the day before.

Thanks to Andrew Grieve, King’s College London, for the Regent Street data.

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