The Earl of Dalkeithasked the Minister of Transport whether he will introduce the appropriate regulations or, if necessary, legislation at an early date to ensure that the discharge of exhaust fumes from motor lorries is in an upward direction from a point no lower than the roof of the vehicle's cabin in order to lessen the risk of semi-asphyxiation of other road users, particularly in traffic jams, and to improve visibility for overtaking vehicles.
§ Mr. Tom FraserNo. The vertical discharge of vehicle exhaust gases at cab roof level has positive disadvantages. Many of the constituents of these exhaust emissions, especially diesel oil smuts, are heavier than air and are better blown out near the ground than on to the heads of passers-by or into first-floor windows. Further, the shape of many vehicles is such that, when in motion, the air-flow produced would draw exhaust emissions down at the rear on to following vehicles.
There is no technical reason why diesel engined goods vehicles should not be prevented from emitting excessive smoke. The road-side "spot checks" carried out by my technical officers and other preventive measures are designed to reduce the incidence of diesel smoke emission.