Plans for an Ultra low emissions zone, to be implemented in 2020, are under consideration.

This is as part of the Ultra Low Emissions Zone scheme.

On Wednesday he announced his vision to see the world's first "Ultra Low Emission Zone," meaning by 2020 only zero or low-emission cars would be allowed into central London.

Tariffs would also vary according to how polluting a vehicle was, making it also "potentially a replacement for the [planned] ultra low emission zone, which is going to be inadequate."

That's why we support the mayor of London's "ultra low emission zone" and investments like Crossrail and the cycle superhighways, and why we want to see a big expansion of charging points for electric vehicles too.

On buses, he pledged that every one in Greater London would be "at the very least" compliant with the requirements of the forthcoming Ultra Low Emissions Zone (ULEZ) by 2025, through a combination of new buses coming on stream and retrofitting.

The Tory AM also wants cabbies to have more freedom to vary their fares and black cabs to be exempted from the strictures of the forthcoming Central London Ultra Low Emissions Zone until it comes into force for all other motor vehicles in 2020, rather facing new restrictions from 2018 as presently scheduled.

Boris Johnson has plans to bring in an "ultra low emission zone" in central London but the plan will not be rolled out until 2020.

But these numbers are much worse than the 7,500 total deaths attributable to long-term exposure to air pollution that we estimated from the Mayor's Ultra Low Emission Zone consultation documents late last year.

The Mayor has also confirmed the introduction of the Ultra Low Emission Zone in London from 2020.

In a letter, giving the Government the 10-day deadline, ClientEarth argued Boris Johnson's plans for an ultra low emission zone by 2020 do not cover many polluted roads outside the area.

Around a 1,000 of the totalled deaths could be saved by 2020 by measures previously brought in by Boris Johnson, without his flagship ultra low emission zone (ULEZ).

The Mayor expects that by introducing new zero emission capable taxis and the world's first Ultra Low Emission Zone from 2020, there will be 70 per cent reduction in the number of Wandsworth residents living in areas breaching NO2 limits and significant improvements elsewhere in the capital.

Mr Johnson has already proposed hiking the congestion charge for many diesel vehicles, so it could double to £20, rather than banning them from his planned ultra low emission zone due to be introduced in 2020.

However, the Mayor recognises that more needs to be done and has proposed a central London Ultra Low Emission Zone from 2020 and a number of other measures to help ensure continued improvements in London's air quality.

At the heart of his plans is the world's first Ultra Low Emission Zone in central London from 2020.

In a statement earlier this week, Matthew Pencharz , senior environment and energy adviser to the Mayor, said plans are in place to introduce an Ultra Low Emission Zone.

Labour said the Mayor had not taken the problem seriously enough with his Ultra Low Emission Zone not due to be introduced until four years after he has left City Hall in 2016.

Instead, the Mayor has committed millions of pounds to delivering pioneering initiatives, including proposing a new Ultra Low Emission Zone and creating Europe's largest fleet of hybrid buses to improve air quality.

Alongside the world's first Ultra Low Emission Zone from 2020 these measures will boost jobs and growth in the development and manufacturing of ultra low emission technologies, secure the long-term future of the taxi industry, and ensure everyone who lives, works in, or visits our city has the cleanest possible air to breathe.

He'd like the ULEZ brought in earlier to lessen diesel fumes.

But he wants to introduce ULEZ sooner than 2020 and look at expanding it to cover wider arterial roads.

On buses, he pledged that every one in Greater London would be "at the very least" compliant with the requirements of the forthcoming Ultra Low Emissions Zone (ULEZ) by 2025, through a combination of new buses coming on stream and retrofitting.

Around a 1,000 of the totalled deaths could be saved by 2020 by measures previously brought in by Boris Johnson, without his flagship ultra low emission zone (ULEZ).

Defending his actions, including ordering all taxis to be zero-emission capable by 2018 and his ULEZ, Mr Johnson said: "This study shows imperatively why these bold measures are required. "