While diesel cars aren’t particularly common in the U.S., they’re abundant on European roads. That’s because they burn fuel more efficiently than petrol engines, and fuel prices are significantly higher on the other side of the Atlantic Ocean. Diesel and gas cost around 60 and 64 cents per liter respectively in the U.S., compared to $1.30 and $1.50 in France.

But while diesel engines may be more efficient, the combustion of the fuel also produces larger quantities of soot and nitrogen oxides compared to gasoline. And recent research showed that those particulates contribute to the deaths of over three million people each year around the world.

Attempts to clean up the act of diesel cars haven’t gone well. Most famously, Volkswagen’s “clean diesel” automobiles were found to be nothing of the sort. Instead, Paris, Madrid, Athens, and Mexico City will simply ban cars from using the fuel. It’s currently unclear exactly how the initiative will work, as the cities haven’t said exactly which parts of their centers will be subjected to the rules, or how the ban will be phased in.

Despite being inspired by air quality, the rule will also have positive impacts on the climate. Mexico City mayor Miguel Ángel Mancera thinks it’s a chance to boost public transport provision, while the mayor of Athens, Giorgos Kaminis, sees it as part of a longer-term plan to bans car from cities altogether.

 It will also help drive electric car adoption. As MIT Technology Review has argued in the past, it is exactly these kinds of dramatic regulatory changes that are required to spur sustainable energy adoption.