POLYCYCLIC AROMATIC-HYDROCARBONS IN CENTRAL LONDON AIR DURING 1991 AND 1992

The results of monitoring for 18 polycyclic aromatic hydrocarbons (PAH ) at Exhibition Road, London, UK during the period from January 1991 t o September 1992 are presented. Although both particulate and gaseous PAH were analysed, the results are expressed as total PAH. The PAH mea surements are complemented by the simultaneous monitoring of a range o f air quality variables. These parameters have been subjected to corre lation analysis and the dependence on motor vehicle emissions for many of the PAH species is inferred. The majority of the PAH displayed hig her annual mean concentrations during 1991 than previous measurements taken at the same site in 1987. The impact of motor vehicle emission l egislation, the increased use of unleaded petrol and the rise in the u se of diesel powered motor vehicles are all discussed in the context o f the presented results. A pollution event during December 1991 caused significantly increased PAH concentrations. A comparison with PAH dat a from another site in London indicates good agreement between the two sets of data.