Charges for driving the oldest, most-polluting vehicles into central London have almost doubled after a £10 toxicity T-Charge came into force.
The fee applies mainly to diesel and petrol vehicles registered before 2006 and covers the same area and operating times as the existing congestion charge zone.
Drivers already faced an £11.50 daily fee for entering the central London zone on weekdays between 7am and 6pm.
The T-Charge is an additional cost, taking the total to £21.50.
Mayor Sadiq Khan, who introduced the scheme, claimed London now has “the world’s toughest emission standard”.
He said he is taking “urgent action to help clean up London’s lethal air”.
The mayor went on: “The shameful scale of the public health crisis London faces, with thousands of premature deaths caused by air pollution, must be addressed.
“Today marks a major milestone in this journey with the introduction of the T-Charge to encourage motorists to ditch polluting, harmful vehicles.”
Friends Of The Earth air pollution campaigner Jenny Bates believes the mayor is “right to try to dissuade drivers bringing the oldest, dirtiest vehicles into central London” but warned it is “only one small step towards clean air”.
She said: “We urgently need a programme of meaningful financial assistance to help drivers of the dirtiest vehicles switch to something cleaner, and bold policies to cut traffic overall.”
RAC roads policy spokesman Nick Lyes accepted that “the mayor is right to take action over the oldest vehicles “because these are more likely to be the most polluting”, but warned that “drivers may also see themselves as an easy target”.
He said: “While some car emissions are a contributory factor to poor air quality, the mayor needs to look at other sectors such as industry, domestic boilers and even his own bus fleet where he should be accelerating transition to zero emission as soon as possible.”
AA president Edmund King said the large majority of London drivers support measures to improve air quality but “it is crucial to get the balance right”.
He said: “In the pursuit of cleaner air, Londoners will need to be convinced that public transport is affordable and reliable enough to use.
“Failing that, they will need assistance to convert non-compliant vehicles to ones which the mayor deems suitable.
“This new T-Charge should not be seen as an excuse for the London boroughs to introduce their own charging or parking schemes which aim to demonise diesels whether driven or not.”
Cyclists in Bloomsbury (Stefan Rousseau/PA)
The T-Charge is the first of a series of new rates being introduced in London.
It is due to be replaced by a stricter Ultra-Low Emission Zone in 2020, although Mr Khan is consulting on bringing this forward to 2019.
This will apply 24 hours a day every day and mean diesel cars registered before September 2015 and petrol cars registered before 2006 will face a £12.50 charge.
The mayor hopes to expand the area covered for cars and vans up to the North and South Circular roads in 2021.