Under the European Communities (Vehicle Testing) Regulations, 1991 to 1999, all buses and coaches over one year old are already required to undergo roadworthiness testing on an annual basis. Testing is carried out at test centres, including certain CIE centres, appointed and supervised by local licensing authorities. The test includes the checking of exhaust emissions.
Article 30 of the Road Traffic (Construction, Equipment and Use of Vehicles) Regulations, 1963 to 1998, requires vehicles to be so constructed as to prevent so far as is reasonably possible the emission of smoke, visible vapour, noxious gases or offensive odours. Article 90 of these regulations prohibits a person using a vehicle in such a manner as to emit fumes which could be prevented by the exercise of reasonable care. Enforcement of these regulations is a matter for the Garda Síochána.