Mr. G. Wilsonasked the Minister of Transport if he has considered the advantages and disadvantages of requiring diesel-engined vehicles to be fitted with vertical exhaust pipes; and if he will make a statement.
§ Mr. MarplesYes. In tests here and in the U.S.A. vertical exhaust pipes showed no advantages in reducing urban air pollution, and there were positive disadvantages. For example, many exhaust constituents, especially diesel oil smuts, are heavier than air; they are better blown out near the ground than into windows and onto the heads of passers-by. The shape of many vehicles also produces an air-flow when moving that would draw exhaust down at the rear in the face of following vehicles.