Roadside inspectors found 293 lorries fitted with emissions cheat devices at checks carried out across five locations between August and November 2017, the Driver and Vehicle Standards Agency (DVSA) has revealed.
Officers were instructed to check for the use of â€˜defeat devicesâ€™ that mask the emission of harmful air pollutants and to ensure that diesel particulate filters had not been removed from vehicles, as part of standard roadside safety checks carried out by the Agency.
DVSA examiners searched 3,735 lorries at these locations during the four month period and found 293 lorries with a cheat device fitted.
Northern Ireland registered vehicles were found to have the highest proportion of vehicles with a cheat device â€“ 20.4% of those inspected, compared to 8.5% registered in Great Britain and 4.9% registered outside of the UK.
In total 7.8% of the lorries checks carried some sort of emissions cheat device, the figures reveal.
Inspectors also found that some vehicles had been using fake emission reduction devices or diesel exhaust fluid, had illegal engine modifications resulting in excessive emissions or had exhaust gas recirculation valves removed, DVSA said.
The drivers and operators were given 10 days to fix the emissions system, or face a Â£300 fine and have the vehicle taken off the road.
Following the roadside checks, DVSA examiners are inspecting more than 100 operatorsâ€™ vehicle fleets for emission cheat devices. DVSA will also start checking for emissions cheat devices at more locations across Great Britain from Spring 2018.
Gareth Llewellyn, DVSA chief executive, said: â€DVSAâ€™s priority is to protect you 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.
â€œAnyone 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€
Richard Turfitt, Senior Traffic Commissioner, said: â€œTraffic Commissioners welcome the steps being taken by the enforcement agency to identify emissions cheats.
â€œUse of these devices threatens to undercut responsible and compliant operators as well as damaging the environment and public health.
â€œTraffic Commissioners will look to take action wherever an operator seeks an unfair and illegal advantage over the rest of industry.â€
The Road Haulage Association (RHA), which represents the road transport and freight logistics industry has said it supports the action by DVSA, and called for vehicle operators to ensure that they comply with vehicle emissions requirements.
A spokesperson for the RHA said: â€œCompliance is a big issue. If you are not compliant you run a big risk of losing your operatorâ€™s licence and those hauliers that do flout the law in that way are putting their business at risk. We support the DVSA in finding out who these operators are.â€