It has been on the cards for quite some time, but still this expansion of the Ultra Low Emission Zone (ULEZ), will be an initial shock for drivers.

London authorities say 10 million people have visited the ULEZ website, but some reports suggest that less than half of the capital's drivers are aware of the changes.

The zone is now 18 times bigger than the original zone established three years ago.

It is ringed by two routes, the north and south circulars, historic ring roads from a time when London was a much smaller city and there was no M25 forming a much larger circle around it.

The idea is to improve London's poor air quality and in fact a lot of cars will by now be ULEZ compliant, but an estimated 135,000 vehicles in London are not.

Broadly speaking petrol cars manufactured before 2005 and diesel cars and vans before 2015 now face a $17.20 charge every time they enter the zone, with a non-payment penalty of up to $220.

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Sums that soon add up if you're a regular commuter.

Many campaigners complain that low-income families and businesses will be hit hardest by the new charge.

And the new map means it's pretty impossible to do any kind of business in London without crossing that invisible line.

The Mayor of London, Sadiq Khan, says the improved air quality is for the benefit of London's residents. He also said that six out of ten families inside the ULEZ zone do not even own cars.

He also said that even on day one the air quality noticeably improved in central London.

Thousands of drivers will now be going online to check their registrations on the ULEZ website to see whether or not their vehicle complies.

The city's authorities are hoping that this will guarantee cleaner air for the 3.8 million residents that live within the new boundary - air pollution is a growing health concern across British cities.

The number of people in the zone is double the population of Paris and eight times the population of Manchester.

The mayor's office has said 4,000 Londoners are dying prematurely each year due to toxic air, while children are growing up with stunted lungs.

Other cities operating an ULEZ are Birmingham and Bath, with Bristol, Edinburgh, Manchester and Glasgow set to follow soon.

It presents a dilemma for thousands of motorists, but with the COP 26 summit just round the corner it is hard to conclude it is anything but necessary.