More than 100 HGV operators have been caught by government inspectors using â€œcheat devicesâ€ to alter their vehiclesâ€™ emission readings.
In August 2017, the Driver and Vehicle Standards Agency (DVSA) started to include checks for emissions cheat devices in roadside checks at five locations across Great Britain.
By the end of November, examiners had searched 3,735 lorries and found 293 lorries with a cheat device fitted.
The devices, which take various forms, alter a vehicleâ€™s emissions reading and potentially mean it emits far higher levels of pollution than it should. The advantage to operators is that the devices can cut the cost of running the vehicle.
If they are caught and do not fix the cheat within 10 day, drivers and operators can face a fine of Â£300 and having the vehicle taken off the road. Repeat offenders can see their vehicle seized on the spot.
Gareth Llewellyn, DVSA chief executive, said: â€œDVSAâ€™s priority is to protect [the public] from unsafe drivers and vehicles.
â€œWe are committed to taking dangerous lorries off Britainâ€™s roads. Stopping emissions fraud is a vital part of that.
Anyone who flouts the law is putting the quality of our air and the health of vulnerable people, at risk. We wonâ€™t hesitate to take action against these drivers, operators and vehicles.â€
The roadside checks found that 7.8 per cent of all lorries checked were fitted with some sort of emissions cheat. That rose to 8.5 per cent of vehicles registered in Great Britain and 20.4 per cent of Northern Irish-registered vehicles.
Among the techniques uncovered during the inspections were using devices designed to stop emissions control systems from working; removing the diesel particulate filter; using cheap, fake emission reduction devices or diesel exhaust fluid ;using illegal engine modifications which result in excessive emissions; removing or bypassing the exhaust gas recirculation valve.
Following the roadside checks, DVSA examiners are inspecting more than 100 operatorsâ€™ entire fleets for cheat devices. Some of the companies being inspected operate up to 80 vehicles.
The DVSA has also said that it will extend the checks to more inspections sites around the country this year.