£10 T-charge for high polluting vehicles starts in London today

Hybrids exempt from UK petrol and diesel car ban

The capital already has a Low Emission Zone, but this does not currently apply to cars or motorbikes.

Elsewhere, a set of 'clean bus corridors' have been proposed, which would see the cleanest buses placed on the dirtiest road routes in a bid to tackle emissions. Khan has also given Transport for London (TfL) the green light to investigate whether a diesel scrappage scheme could work in the capital. The scheme, which would offer cash incentives to diesel drivers to encourage them to choose a cleaner car, has previously been shot down by MPs, who claimed it would be ineffective and expensive to manage.

When he initially announced the plans last year, Khan said he wanted to act "before an emergency, which is why we need big, bold and sometimes difficult policies if London is to meet the scale of the challenge.

Oxford plans to ban petrol and diesel cars from 2020

"I have been elected with a clear mandate to clean up London's air. The previous mayor was too slow on this issue, the government has been hopelessly inactive and it's Londoners who are suffering as a result."

Khan cited medical research, which claims that more than 10,000 people die annually in London due to polluted air. London's air quality has come under close scrutiny in recent years, particularly in relation to NOx emissions. Parts of the capital regularly breach EU limits for NOx; Putney High Street in West London breached the EU's annual limit just one week into 2016.

Despite his tough stance on pollution, Khan's proposals aren't the country's hardest. Oxford City Council is pushing for petrol and diesel cars to be banned from its urban centre from 2020. The policy is currently being subjected to a public consultation.

Darren Moss and Sam Sheehan