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Do clean air zones work?

Do clean air zones work?


A by-election result on the outskirts of London has turned London’s Ultra Low Emissions Zone into a political football, but does it improve air quality?

The recent by-election in Boris Johnson’s former seat of Uxbridge and South Ruislip has led to questions about the expansion of London’s Ultra Low Emission Zone.

Ulez is designed to improve air quality in London by charging drivers of polluting vehicles £12.50 a day to enter the city. 

The Conservatives weaponised the planned expansion in an area where large numbers of people rely on their cars and it managed to hold onto the constituency. Although its majority was cut from 7,210 to 495.

The result led to recriminations within the Labour Party with some, including leader Keir Starmer, blaming the Ulez expansion for their narrow loss. 

But Ulez does what it is designed to do. It improves air quality.

Jeevan Vasagar, Tortoise’s climate editor, says air pollution is “one of the biggest environmental threats to public health in the UK. Around 4,000 deaths in London in 2019 were attributed to toxic air.”

Clean air zones like Ulez are the fastest way to reduce nitrogen dioxide, a pollutant that is particularly harmful to people’s lungs.

“Levels of that pollutant have dropped by almost half compared with the projected trend had Ulez not been in place,” Vasagar says.

“One of the big political questions is who exactly will be affected by the expansion of Ulez… We don’t know what kind of political pain that’s going to cause.”

Labour and the Conservatives think the result in Uxbridge and South Ruislip has given them a glimpse of the political pain that some green policies might cause. 

But it’s not clear how much can actually be learnt from a single by-election result. Voters are often more focussed on local issues when they go to the polls outside of a general election, but that hasn’t stopped Labour being spooked and the Conservatives being emboldened. 

Expect to see them trying to repeat the Uxbridge playbook on a national level.

Today’s episode was written and mixed by Rebecca Moore with reporting from Jeevan Vasagar.