LONDON (AP) — The mayor of London says drivers of the most polluting cars will have to pay a 12.50 pound ($15.55) charge to drive in the city in a bid to improve air quality.

Mayor Sadiq Khan says the charge will start in April 2019 and apply to diesel cars more than four years old and petrol cars more than 13 years old. It will initially cover central London, with plans to widen the zone by 2021.

The plan aims to halve emissions of nitrogen oxides from vehicles by 2020.

Khan said Tuesday that "the air in London is lethal and I will not stand by and do nothing."

Diesel vehicles emit high levels of nitrogen oxides, which have been linked to health problems including heart and lung disease.