Campaigners have cheered the introduction of tough new limits on road emissions which come into force today in London.

The new Ultra Low Emission Zone (ULEZ) will see vehicles that fail to meet new emissions standards charged a hefty fee for entering the city centre, as part of the latest effort from London Mayor Sadiq Khan to bring the city's air pollution under control.

Hailed as "one of the most ambitious schemes of its kind in the world", thousands of cars, vans, and motorbikes will have to pay an extra £12.50 to enter London today, on top of the existing £11.50 Congestion Charge. Lorries, buses, and coaches that fail to meet the new emissions standard will be charged £100 a day extra.

With road transport responsible for around half of air pollutants, the central London ULEZ aims to reduce toxic emissions from road transport by around 45 per cent, the Mayor's Office claims.

It expects ULEZ - which will operate 24 hours a day - to impact around 60,000 vehicles every day. Most cars more than four years old will have to pay the charges, giving London some of the tightest emissions standards of any city in the world.

All the cash raised from charges will go to Transport for London and will be earmarked for improving the city's fleet of buses as well as its tube, cycle, and rail connectivity, Khan has promised.

The Mayor's Office has spent months preparing for ULEZ introduction, investing in more electric buses, rolling out charge points for electric vehicle (EV) black cabs, and launching a scrappage scheme for small businesses and owners of older vans.

Campaigners said the rollout marks a "positive step" for air pollution efforts in London, while noting further action will still be necessary.

"With thousands of premature deaths in London every year because of dangerously toxic air it's clear that tough action is needed to end this health crisis," said Friends of the Earth's air pollution campaigner Jenny Bates. "The ULEZ has a crucial role to play in cleaning up the capital's filthy air - but a strengthened scheme and additional measures are needed to protect the health of all Londoners."

Poppy Welch, head of Go Ultra Low, the joint government and industry campaign to promote the uptake of EVs, said ULEZ is one of a number of drivers making electric cars more attractive to businesss.

"For businesses regularly driving in London, the introduction of the Ultra Low Emission Zone means there has never been a better time to consider incorporating electric vehicles into fleets," she said. "Offering exemptions from both the Ultra Low Emission and Congestion Charge zones, cheaper running, maintenance and tax costs, as well as a government grant towards the purchase price of qualifying zero emission vehicles, they can offer considerable whole life cost savings. With a number of other cities, including Leeds and Birmingham, set to introduce clean air zones over the coming years, now could be the perfect time to invest in a lower emission, and lower cost, electric vehicle fleet."

Meanwhile, the British Heart Foundation called for other cities across the UK to introduce their own Ultra Low Emission Zones to help tackle the estimated 36,000 premature deaths a year caused by air pollution.

Many cities across the UK are in breach of EU air quality rules and are required to come forward with new air quality action plans. However, some councils are understood to have missed deadlines for submitting their plans and have been warned by campaigners that they risk legal action unless they deliver sufficiently ambitious plans.

However, alongside those welcoming the introduction of the ULEZ some have warned it could have an adverse impact on small businesses.

While welcoming ULEZ as a " really positive step" for improving air quality, CBI London Director Eddie Curzon warned "smaller firms can struggle to afford the switch to low emission vehicles, and for some larger vehicles, there are simply no low emission alternatives available."

"To make a success of the ULEZ, it is crucial that City Hall works with firms to help them take advantage of new technologies and support them, where required, to accelerate the take up of low emission vehicles," he said.

The Mayor's Office has introduced a £23m scrappage scheme to help small businesses cover some of the cost of switching to cleaner vehicles, but it is restricted to charities and microbusinesses with fewer than 10 employees.