§ Mr. Tony LloydTo ask the Secretary of State for Transport what estimates he has as to the contribution of the worst(a) 10 per cent. and (b) 20 per cent. of vehicles to noxious and harmful vehicle emissions. [36640]
§ Mr. NorrisVehicle emissions are strongly influenced by operating conditions and driver behaviour. However, in an analysis of exhaust emission measurements, carried out by the Transport Research Laboratory on a sample of 200 cars selected to be typical of the in-service fleet, 10 per cent. were found to contribute 22 per cent. of total carbon monoxide and 27 per cent. of total hydrocarbon emissions under urban driving conditions; similarly, 20 per cent. of cars tested contributed 39 per cent. of CO and 40 per cent. of HC emissions.