THE VARIATION IN VOLATILE ORGANIC-COMPOUND CONCENTRATIONS IN CENTRAL LONDON BETWEEN 1986 AND 1992

The results of air pollution monitoring at Exhibition Road, London, UK, during the periods August 1986, February to December 1987 and July 1991 to September 1992 are presented. Thirteen ambient volatile organic compounds (VOC) ranging from C3 to C8 are reported. The summary data were derived from daytime means. The annual cycle of higher ambient concentrations during the winter-time was highlighted by the occurrence of air pollution events during December 1987 and December 1991. Motor vehicle emissions were the predominant source of most of the ambient VOC. The influence of Reid Vapour Pressure of petrol upon the evaporative emissions, in particular n-butane, was inferred. The sources and behaviour of evaporative emissions are also reviewed. High ambient concentrations of C5 VOC, in particular i-pentane, were measured during 1986/87.