Diesel cars: Why the fuel is now new evil

In 1997, the British government signed the Kyoto treaty, committing it to strict targets on carbon emissions.

Gordon Brown, then chancellor of the exchequer, spoke of a need for people to drive more fuel-efficient cars.

So it seemed only logical to create incentives for people to ditch their gas guzzlers in favour of fuel-sipping diesels, which produced far less in carbon emissions.

The future, it seemed, was diesel.

What a difference 20 years makes.

On the eve of the 2017 Budget, Chancellor Philip Hammond is now under enormous pressure to abandon past thinking and make it more expensive to drive diesel cars.

Claims that diesels cause health risks ranging from cancer to dementia, not helped by the Volkswagen emissions scandal, have done little to increase confidence in the fuel.

There have even been calls to ban oil-burning vehicles from city centres. Traffic fumes, particularly those from diesel vehicles, are reported to be responsible for about 40,000 premature deaths a year across the UK.

In short, diesel has become a dirty word.

Last week, nine of the country's most senior medics sent a letter to Mr Hammond, to reverse Gordon Brown's incentives and increase road tax for diesel cars.

Mr Hammond is understood to be considering incentives to reduce the number of diesel cars in the UK in tomorrow's Budget, although how far he will go is not known.

If he does choose to go down this route, he might find a surprising ally in Labour front-bencher Barry Gardiner, who freely admits that the Blair-Brown governments got it wrong.

"Hands up – there's absolutely no question the decision we took was the wrong decision," Mr Gardiner admitted two years ago, when serving as shadow environment minister.

"At that time we didn't have the evidence that subsequently we did have."

The problem is that while the politicians might have done an about turn on the merits of diesel cars, there are now an awful lot of them on the roads. Back in the 1970s, diesel cars were almost unknown in the UK, although they were considerably more popular in mainland Europe. By 2001, the number had risen to 13.8 per cent of new car sales in Britain.

That year, Mr Brown introduced a new sliding scale of road tax charges, which made diesel vehicles in particular more attractive. The "scrappage" scheme of 2009 not only introduced a new word to our vocabulary, it also led to 392,000 people handing their old cars over to the scrapman in exchange for a £2,000 discount on a new one. It is a fair bet that many of these customers would have made the switch to diesel.

In 2015, there were reported to be 11.9 million diesel cars in the UK, one of the largest fleets in Europe.

The medics, led by Professor Jonathan Grigg, of the Doctors Against Diesel campaign, claim that the increase in the number of diesel cars has had an unprecedented impact on air quality and health.

"Diesel emits nitrogen oxides and particulates, both major contributors to air pollution and which have contributed to the UK regularly breaching legal limits on air pollution," their letter said.

"Nitrogen dioxide is estimated to lead to 5,600 premature deaths per year in London, and air pollution is linked to a range of health impacts throughout the life-course, beginning before birth and including asthma, stroke, heart disease, obesity, diabetes and dementia."

The medics added that children were significantly at risk, with studies linking air pollution to impaired lung growth.

Professor Grigg, professor of paediatric respiratory and environmental medicine at Queen Mary University of London, goes one stage further. He calls for a new "scrappage" scheme, to get older diesels off the road.

"It is vital that diesel emissions from our roads are reduced as quickly as possible and using diesel cars and vans must cost more than using less polluting vehicles," he says.

So why have attitudes towards diesels changed so much in such a short time?

The main reason was that at the time Mr Brown reformed the road tax system, the focus was very much on cutting carbon emissions.

But while diesel cars typically produce 15 per cent less carbon dioxide than the equivalent petrol models, they also churn out four times more nitrogen dioxide and 22 times more particulates, tiny particles that penetrate the lungs, brain and heart.

However, while some doctors may wish to see a change to the tax system to make diesel less attractive, not everyone is convinced.

At the same time as the medics sent off their letter to Mr Hammond last week, West Midland euro-MP and Ukip transport spokesman Jill Seymour launched a petition of her own, calling on action from the Government to protect diesel drivers.

Shropshire-based Mrs Seymour voices concern at threats by councils to introduce higher parking charges for diesel cars, as well as "pollution taxes" in city centres.

"There is a growing move to charge drivers of diesel cars extra for parking and travelling in city centres, even though the Government encouraged people to buy them by highlighting their efficiency and low carbon dioxide emissions," she says.

"That's why this complete policy U-turn is unfair. People with diesel cars should not now be suddenly discriminated against, charged more for parking or forced to pay additional costs to use their vehicles."

Her petition calls on Prime Minister Theresa May to protect people who bought diesel cars, claiming they are still among the most efficient vehicles available.

It also asks the Government to stop any current or proposed charges which discriminate against diesel engine cars from being levied by councils and local authorities.

Transport Secretary Chris Grayling recently urged people to think long and hard before buying a diesel car, and the Government is reported to be considering proposals for a scrappage scheme.

Mrs Seymour says any attempts to reduce the number of diesels should focus more on the carrot than the stick.

"Before the Government allows councils to penalise diesel car owners, it needs to be offering them significant incentives to change their vehicles," she says.

And of course, regardless of whether Mr Hammond goes for the stick or carrot approach, there is another problem with trying to persuade people to switch back to petrol power. The Kyoto carbon-reduction commitments which the Government is still committed to.

Nobody said this was going to be easy.