Analysis and interpretation of the continuous hourly monitoring data for 26 C2–C8 hydrocarbons at 12 United Kingdom sites during 1996

A fully automatic network with 11 urban background and one rural site has been set up and operated successfully in the UK to measure, continuously, hourly concentrations of 26 C2–C8 hydrocarbons; the measurements collected form one of the largest data sets of urban hydrocarbon air quality data available anywhere in Europe. The hourly data have been analysed on a site-by-site and hydrocarbon-by-hydrocarbon basis by constructing scatter plots against benzene. From these scatter plots a number of important sources of hydrocarbon emissions have clearly been identified including: motor vehicle exhaust and evaporative emissions, natural gas leakage, petrol station forecourt evaporative emissions and industrial sources. Overall, urban background hydrocarbon air quality is heavily influenced by motor vehicles and the general pattern of relative concentrations has been accurately defined for the United Kingdom as ratios relative to benzene. Comparisons of these concentrations are made with data for other major cities and with European regional data.