§ Mr. Tony LloydTo ask the Secretary of State for the Environment what assessment he has made of the impact of car-induced air pollution in urban areas and the estimated impact if the number of car journeys were(a) reduced and (b) increased by 10 per cent.
§ Mr. TrippierCars are responsible for about 81 per cent. of national emissions of carbon monoxide, 23 per cent. of national emissions of oxides of nitrogen and 28 per cent. of national emissions of volatile organic hydrocarbons. Estimates for central London suggest that petrol-driven vehicles contributed 46 per cent. to annual mean concentrations of oxides of nitrogen. However, emissions depend not only on the number of car journeys, but on road speed and traffic congestion. It is not presently possible to make precise estimates of the impact of a change in driving habits on urban air quality.