The number of the most polluting vehicles driven in London has fallen by 45%, according to Transport for London (TfL), a local governing body responsible for most transportation in England’s capital. According to The Guardian, the drop-off came after the capital expanded its ultra-low emission zone (Ulez), removing almost 80,000 old cars from roads.

Roughly 77,000 fewer non-compliant vans and cars were detected on an average day in London during September 2023, the first month of operation of the expanded zone, a 45% decrease from June 2023.

Currently, just 5% of vehicles driven in London are non-compliant, meaning they could be potentially charged $15.15 daily, according to a progress report from the London Transit Authority.

Sadiq Khan, the mayor of London, said that the newest figures were a “testament to the huge progress we’ve made in tackling toxic air pollution.”

TfL said that the plan was “highly effective” and that over 95% of vehicles are now compliant, a 10% increase from when the expansion plan was first announced in May 2022.

TfL and Khan said that any net revenue raised through the Ulez program will be reinvested in public transport, including expanding bus services outside of London.

“I’ve always said that the decision to expand the Ulez was very difficult, but a month on from the expansion we can already see that it is working,” said Khan. “London is now home to the world’s largest clean air zone. This will make a huge difference to the lives and health of Londoners... For the remaining Londoners still driving non-compliant vehicles, millions of pounds of scrappage scheme support is still available.”