Emission limits

The limits for different pollutants are detailed in the Road Vehicles (Construction and Use) Regulations 1986.

Petrol vehicles

All new petrol vehicles have to meet limits for hydrocarbons, nitrogen oxides and carbon monoxide

The limits depend on the age of the vehicle:

• Vehicles used before the 1st August 1975 are tested visually
• Vehicles used first between 1st August 1975 and 1st August 1986 must have carbon monoxide not exceeding 4.5% and hydrocarbons 0.12% of total exhaust emissions by volume
• Vehicles first used after 1st August 1986 the carbon monoxide value drops to 3.5%

Diesel vehicles

• Vehicles first used before 1st August 1979 are tested visually
• Vehicles first used after 1st August 1979 have a metered smoke test