Cold starts and emissions from cars equipped with catalytic converters.

This report deals with a general calculation of the significance of cold starts in the total exhaust emissions. The calculations are based on a study of a smaller number of cars tested by the Swedish Motor Vehicle Inspection Company and Volvo, and on a travel pattern survey performed by Statistics Sweden. It has been found that a large proportion of emissions are formed during the first kilometre driven after a cold start This study has tried to calculate the quantity of exhaust emissions which can be directly attributed to the starting sequence. The results of the report confirm that cold starts are responsible for the major part of the environmental impact from cars equipped with catalytic converter. By combining laboratory data with travel pattern data, the report shows that approximately 90% of all carbon monoxide and hydrocarbons are emitted at cold starts. When it comes to nitric oxides, 50-70% are formed in conjunction with cold starts.