London, San Francisco and Beijing are among 19 global cities that have achieved “remarkable reductions” in air pollution, analysis has found, having slashed levels of two airway-aggravating pollutants by more than 20% since 2010.
The analysis found interventions such as cycle lanes, uptake of electric cars and restrictions on polluting vehicles had helped to drive the improvements.
Beijing and Warsaw topped the ranking for cleaning up fine particulate pollution (PM2.5), reducing levels by more than 45%, while Amsterdam and Rotterdam saw the greatest improvement in nitrogen dioxide (NO2), with cuts of more than 40%.
San Francisco was the only US city that cut levels of both pollutants by more than 20%, according to the analysis of nearly 100 cities around the world. China and Hong Kong are home to nine of the 19 cities, with European cities making up the rest.
There’s a lot of evidence that it has not moved elsewhere. Let’s look at New York City for example: reducing car traffic inside the zone cut pollution outside the zone by reducing traffic there too
There are very narrow examples where what you describe isn’t impossible, but they tend to involve all-coal electric supply combined with first-generation electric vehicles. Eg: West Virginia 20 years ago.