People walk on the Champs-Élysées on the day that central Paris went car-free.Philippe Wojazer / Reuters

So successful was Paris’s first “day without cars” on September 27 that the city’s mayor wants to expand the effort to help clean up the city’s terrible air quality. The single-day initiative made 30 percent of the city’s roads off-limits to automobiles, but even that minor reduction in traffic was enough to cut pollution levels—and noise—significantly.

The Guardian reports that according to Airparif, which measures city pollution levels, some parts of Paris registered 40 percent less nitrogen dioxide (which produces smog) in the air on September 27. On the bustling Avenue des Champs-Élysées, nitrogen dioxide levels were 30 percent lower than on other Sundays. And Bruitparif, which measures urban noise, recorded half as much volume in the city center as normal.

Paris has struggled with embarrassingly smoggy air at times this year, and ahead of an international climate meeting in the French capital in November, mayor Anne Hidalgo is on a mission to clean things up.

Hidalgo wants to eliminate diesel use in Paris.

“My goal is to eradicate this harmful fuel in our city.”

Hidalgo is also shooting to get cigarette butts off the street.

Her goal for the next car-free day is to encompass a larger section of the city.

And eventually, the hope would be for Paris to have monthly car-free days, Hidalgo has said.

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