Scores of diesel cars have been illegally belching lethal exhaust fumes in towns and cities across Scotland because their pollution filters have been deliberately removed.

Hundreds more vehicles are likely to have had their filters taken out but escaped detection because the operation has been hidden from MOT inspectors.

The revelations have been condemned as “horrifying” and “sickening” by environmentalists who are calling for a “crack-down” by governments. Scottish ministers are promising action.

Tiny sooty particles emitted by diesel engines are blamed for killing thousands of people every year in Scotland. They have been linked to heart attacks, strokes and cancers.

Since 2009 it’s been compulsory to fit diesel particulate filters (DPFs) in new diesel cars. But in some circumstances they can become clogged with soot, and cause cars to lose power and go into “limp mode”.

It can cost up to £2,500 to have the filters cleaned, but some garages offer to remove them instead for a just a few hundred pounds. While removing the filters may not be illegal, driving a car on the road without one greatly boosts emissions and breaches legal limits.

In 2014 the UK Department for Transport required MOT inspectors to visually check whether DPFs were present, and fail vehicles if they were missing. A regional breakdown released by the department under freedom of information law reveals that 70 vehicles have failed MOT tests across Scotland since then for missing DPFs.

There were ten failures in Edinburgh, ten in Loanhead and seven in Glasgow. There were also multiple failures in Perth, Glenrothes, Falkirk and Bathgate, along with single failures in 33 other towns and cities around the country (see chart below).

But this is likely to be a major underestimate of the scale of the problem because DPF removal can be hidden from MOT inspectors. Autoclinic Remaps in Carluke, South Lanarkshire, openly advertises such a service on its website.

It promises to remove DPFs “while still retaining the housing for MOT purposes”, pointing out that MOT testers only check for the housing. “When we remove a DPF we cut into the housing to remove the insides before welding the original housing up and leave it in place meaning the vehicle WILL NOT fail the MOT test,” the firm says.

On its website Absolute Remaps offers “DPF gutting or removal” in East Kilbride, claiming “your car will become more economical as it can breath a lot easier.” DPF removals are also offered by Infiniti Remapping at Bellshill, North Lanarkshire and Elite Garage Services in Bathgate, West Lothian.


Friends of the Earth Scotland are demanding urgent action from governments in London and Edinburgh. “It is horrifying that companies are dodging around rules that exist to protect everyone from toxic diesel particles,” said the environmental group’s air pollution campaigner, Emilia Hanna.

“The removal of particle filters results in raw, cancer-causing diesel fumes being poured onto our streets. The contempt that some of these companies have for the rules is sickening.”

The 70 vehicles so far caught with missing DPFs in Scotland “are the tip of the iceberg”, Hanna argued. “There are likely to be hundreds, if not thousands, more tampered vehicles on our streets.”

She called on the Department for Transport to close the “crazy” legal loophole that enabled garages to remove DPFs. “This is a scandal that the Scottish Government needs to crack down on,” she said.

The contempt that some of these companies have for the rules is sickening Emilia Hannah, Friends of the Earth Scotland

Dr Fintan Hurley, an air pollution expert from the Institute of Occupational Medicine in Edinburgh, described DPF removal as “very irresponsible”.

It may look like an easy way to save some money or for a garage to build its business, he said. “But air pollution damages health and costs lives. That’s a huge price for other people to pay.”

Jon Bennett from the environment lawyers, ClientEarth, argued it was “highly irresponsible” to worsen the “terrible toll” that air pollution took on the nation’s health. “What revelations like this and the VW ‘dieselgate’ scandal show is that the emissions testing regime we have in this country does not work,” he said.

“We need a national network of clean air zones in our towns and cities, with random on-road testing and an independent labelling scheme that shows potential buyers the true level of a vehicle’s emissions.”

Only one of the four companies offering DPF removal in Scotland responded to requests to comment. Steve Macdonald from Absolute Remaps, said he needed to make changes to his website because his firm no longer offered the service.

They would, however, still reconfigure the electronic control system if customers had removed the filters themselves. “I personally think that there’s a lot more important things to be worrying about in the environment than the DPF removal of a very small fraction of cars that are on the roads today,” he said.

“On the flip side, the car is a lot more economical after the DPF is removed, usually around ten per cent.”

According to the Scottish Government, driving a diesel vehicle without a DPF was illegal because it would not meet air pollution standards. Offenders could be fined up to £1,000 for a car and £2,500 for a van, and it would be up to a court to decide if the person who removed the DPF had committed an offence.

On the flip side, the car is a lot more economical after the diesel particulate filter is removed Steve Macdonald, Absolute Remaps

DPF examinations through roadside testing or annual MOTs were a reserved issue for the UK government, a Scottish Government spokeswoman pointed out. “We have been in contact with the Department for Transport about this issue,” she said.

“The Scottish Government will be asking vehicle manufacturer associations for their views on cleaning a DPF now that businesses in Scotland can offer these services.”

She added: “We are committed to tackling air pollution and are continuing to improve quality, meeting both domestic and European air quality targets across much of Scotland.”

A Department for Transport spokesperson said: “Our changes to the MOT test are helping cut harmful emissions and are taking hundreds of polluting vehicles out of circulation. We are also investigating the latest technology so garages can carry out tougher, smarter tests that will act as a deterrent and keep these cars off the road.”

Vehicles caught without diesel particulate filters

There were also 33 places where one vehicle failed MOT since 2014 because filters had been removed: Aberdeen, Aberdeenshire, Airdrie, Arbroath, Balmedie, Bellshill, Brae, By Kyle, Castle Douglas, Crieff, Dalkeith, Dalry, Dumfries, Dundee, East Kilbride, Eyemouth, Forfar, Fraserburgh, Grangemouth, Greenock, Invergordon, Inverness, Inverurie, Kilmarnock, Kirriemuir, Leven, Livingston, Montrose, Motherwell, Peterhead, Prestonpans, Stirling, Stoneyburn.

You can download the full UK dataset from The Ferret Github account.

A version of the story was published in the Sunday Herald on 26 June 2016.

Photo thanks to Ruben de Rijcke, CC BY-SA 3.0 via Wikimedia Commons.