5. Measurement of volatile hydrocarbons

5.1 Properties of volatile hydrocarbons

Volatile hydrocarbons make up an essential fraction of the volatile organic compounds (VOCs) contained in ambient air. They can be linear, branched or cyclic in structure, saturated (alkanes, cycloalkanes) or unsaturated (aromatics, alkenes, acetylenics, dienes...). Species containing from 1 to around 12 carbon atoms are present as gases or vapors. Above 12 carbon atoms, hydrocarbons are mainly associated with airborne particles. In industrialized countries, fuel combustion, natural gas emissions, industrial and chemical installations, and emissions from landfills and residues are the main anthropogenic sources.

On a national scale, emissions attributable to human activities are mainly due to road transport. In urban areas,...