The
Ultra Low Emission Zone (
ULEZ) is an area in London, England, where an emissions standard based charge is applied to non-compliant road vehicles. Plans were announced by London Mayor Boris Johnson in 2015 for the zone to come into operation in 2020. Sadiq Khan, the subsequent mayor, introduced the zone early in 2019. The zone initially covered Central London, the same area as the existing London congestion charge; in 2021, Khan extended the zone to cover the area within the North Circular and South Circular roads. In 2023 it was further extended to all of Greater London, covering over 1,500 square kilometres (580 sq mi) and approximately 9 million people.