The London Ultra Low Emissions Zone (ULEZ) will be expanded to include the entire greater London area starting next year, according to Mayor Sadiq Khan, who said that the measure will bring cleaner air to 5 million more residents. The move will add a tax of £12.50 ($15.09 USD at current exchange rates) a day to drivers of older and more polluting vehicles across a wider geographical area.

The zone has included the boroughs within the north and south circular roads since last October, The Guardian reports. With this, it will be expanded to include the rest of the city and drivers in the outer boroughs will start having to pay the tax in August 2023.

“The ULEZ so far has been transformational, reducing harmful pollution levels by almost a half in central London,” said Mayor Khan, per the BBC. “But there is still far too much toxic air pollution permanently damaging the health of young Londoners and leading to thousands of early deaths every year, with the greatest number of deaths in the outer London boroughs.”

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Transport for London predicts about 15 percent of vehicles driving in the expanded area – about 160,000 personal vehicles and 42,000 commercial vans daily – will be required to pay the ULEZ tax. According to The Independent, whether a vehicle is charged depends on how much nitrogen dioxide it emits. In general, diesel vehicles registered after 2016, and gas vehicles registered after 2006, are exempt from the tax.

The move has led to resistance from both political rivals and driving groups, who view the tax as an unfair financial burden in a difficult time. Many Londoners, too, oppose the expansion, as a public consultation by Transport for London found that 80 percent of people in the newly announced area oppose being included in the ULEZ.

It has, however, been welcomed by clean air advocates like Rosamund Adoo-Kissi-Debrah. Her nine-year-old daughter, Ella, became the first person in the U.K. to have air pollution listed as a factor in the cause of her death after she tragically passed away in 2013.

“When we had the inquest, we got the experts in Ella’s case to give some recommendations and all of them agreed ULEZ expansion was something that needed to be done to clean up the air in London,” Adoo-Kissi-Debrah said. “Clean air should be a human right.”

In conjunction with the expansion of the ULEZ, Transport for London said that it will expand bus services, help owners of non-compliant vehicles scrap or retrofit them, and that differently abled people who rely on their vehicles will be given an extended grace period.