DRIVERS of polluting cars, lorries and vans will incur automatic penalties under new SNP Government plans to cut air pollution in Scotland’s biggest cities.

A public consultation said ministers want to use number plate recognition cameras to ban dirty vehicles from four Low Emission Zones (LEZs) by 2020, then fine any drivers who stray into them.

The government's preference is for the LEZs in Glasgow, Edinburgh, Aberdeen and Dundee would operate 24/7 all year round.

The RAC said the proposal would leave motorists “reeling”, with diesel cars registered more than three years ago possibly affected.

An LEZ in London has run since 2008 with a daily charge of £100 for vans and minibuses, and £200 for lorries, buses, coaches and other big vehicles failing clean emission standards.

Nicola Sturgeon announced on Tuesday that she wanted four LEZs up and running by 2020, with the first due to be named in the coming months and operational in 2018.

The aim is to improve air quality by reducing exhaust pollutants such as fine particulate matter and nitrogen oxides, which can affect heart and lung functions.

LEZs were first introduced in Sweden in 1996, and there are now more than 250 across Europe, including five in the UK - London, Brighton, Oxford, Nottingham and Norwich.

A three-month consultation on LEZs north of the border says they would target vehicles falling below minimum mandatory European emission standards.

For cars, the minimum standard for petrol is Euro 4, which has applied to cars registered since January 2005, and for diesel Euro 6, meaning cars registered after September 2014.

However councils will decide exactly which vehicles are covered.

LEZs work either by charging dirty vehicles to enter a prescribed area, or banning them and then fining those who enter without a just excuse.

Ministers want to use the ban-and-fine model, with a national penalty scheme for offenders.

Number plate cameras would be the primary means of enforcement.

There would be exemptions for ‘historic’ vehicle classes, military and agricultural vehicles, long-distance buses passing through LEZs, and diverted traffic.

Residents and businesses in LEZs would also be given longer to bring their vehicles up to standard and those unable to afford upgrades could apply for a “hardship exemption”.

The LEZs are part of a package of measures in the annual legislative programme designed to promote cleaner, low carbon technologies and improve the environment.

Transport Minister Humza Yousaf said: “Poor air quality remains a public health issue, particularly for those with respiratory and cardiovascular conditions.

“The vehicles to be included in, or be exempt from, LEZs will be for individual local authorities to decide, but could include freight, taxis, buses and private motor vehicles.”

James Cant, Director at British Heart Foundation Scotland, said: “Outdoor air pollution contributes to an estimated 40,000 premature deaths in the UK each year. The evidence is clear, tackling this must be a priority for the Scottish Government.”

RAC spokesman Nicholas Lyes said: “Nobody doubts the need for bold decisions to tackle Scotland’s pollution issue in its biggest cities, however, these measures could have serious financial and practical impacts on those living and working in and around these cities.

“Unlike the London LEZ, where motorists and businesses had up to six years to plan and budget for upgrades to their vehicles, these proposals appear fast-track stringent restrictions with a limited grace period for those who live or operate businesses in the proposed zones.”

Lawyer Anna Heslop of the environmental pressure group ClientEarth, which had threatened to sue the SNP Government if it failed to tackle dangerous air pollution, said: "There are some ambitious sounding measures here but the Scottish Government needs to make sure that any LEZs are effective as soon as they can be.

“The law says air pollution needs to be brought within legal limits as soon as possible, and we’ll be contacting the Scottish Government to remind them of that."

Scottish Tory MSP Donald Cameron said: “It seems the Scottish Government hasn’t even begun to think this through. How are motorists supposed to prepare for this change while so many details are up in the air?

“The SNP also has to consider the impact this will have on vehicle owners who are on low incomes, and who will be more likely to have older cars which will be hit by this move.”

Green MSP Mark Ruskell said ministers were not acting quickly enough, given there were 38 pollution zones in Scotland where safety standards are regularly broken.

He said: “While we await a decision on where the first of the LEZs will be, there are actions the Scottish Government can take right now to improve air quality in our streets. Reducing the speed limit in built up areas from 30 to 20 mph, as my member's bill proposes, would significantly cut pollution from diesel engines.”