§ Ms ShortTo ask the Secretary of State for the Environment to what extent the projected decrease in emissions of nitrogen dioxide resulting from the introduction of catalytic converters takes into account the effects of cold starts and short journeys within urban areas; and what are the implications of these factors for future urban air quality.
§ Mr. MacleanProjections of emissions of oxides of nitrogen published by Warren Spring Laboratory take account both of the introduction of catalytic converters on cars and of the fact that these do not control emissions effectively until the engine has warmed up. The introduction of catalytic converters is expected to result in a decline both in emissions of oxides of nitrogen and in average concentrations of nitrogen dioxide. However, peak wintertime concentrations of nitrogen dioxide in urban areas will be less affected because of the preponderance of short car journeys and of low ambient temperatures in winter.