Traffic as a source of volatile hydrocarbons in ambient air

In this article ambient measurements of hydrocarbons performed in The Netherlands have been used to validate emission estimates. Emission estimates are usually based on motor vehicle emision factors. The emission factors are derived from dynamometer measurements using prescribed test procedures and related cycles, assumptions regarding vehicle maintenance, the use of catalysts and estimates of non-tailpipe emissions. From the measurements it follows that the hydrocarbon profile emitted by traffic has remained remarkably constant over the last 20 years. Furthermore, it may be concluded that aromatics, olefins and paraffins account for 30%, 15% and 46%, respectively, of the emissions, the remainder consists of acetylene and aldehydes in almost equal amounts.