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 to September 1992 are presented. Although both particulate and gaseous PAH were analysed, the results are expressed as total PAH. The PAH measurements are complemented by the simultaneous monitoring of a range of air quality variables. These parameters have been subjected to correlation analysis and the dependence on motor vehicle emissions for many of the PAH species is inferred. The majority of the PAH displayed higher annual mean concentrations during 1991 than previous measurements taken at the same site in 1987. The impact of motor vehicle emission legislation, the increased use of unleaded petrol and the rise in the use of diesel powered motor vehicles are all discussed in the context of the presented results. A pollution event during December 1991 caused significantly increased PAH concentrations. A comparison with PAH data from another site in London indicates good agreement between the two sets of data.