HC Deb 15 January 1981 vol 996 c591W
Mr. Moate

asked the Secretary of State for Transport if he is satisfied with the present controls and checks on excessive smoke emission from heavy lorries; and what work is being done on objective smoke test methods and suitable equipment.

Mr. Kenneth Clarke

Smoke emission is checked subjectively by the Department's examiners at roadside checks and in the annual test. Each year about 10,500 vehicles are prohibited from use because of excessive emissions. However, the total number of offending vehicles is probably substantially higher than that. With a view to improving enforcement we are studying the possibility of using an objective test method at vehicle testing stations and research is in hand into other ways of determining smoke levels.