TRENDS IN MOTOR-VEHICLE RELATED AIR-POLLUTANTS IN CENTRAL LONDON

Results of intermittent monitoring of six aromatic hydrocarbons (benze ne, toluene, ethylbenzene, m-xylene, p-xylene and o-xylene), carbon mo noxide and oxides of nitrogen over a thirteen year period at a site in central London (Exhibition Road) are presented. Four monitoring regim es were undertaken; namely, 1979, 1982/83, 1986/87 and 1991/92. The su mmertime daytime mean ambient concentrations of the measured parameter s at this site are presented. The reported concentrations show a reduc tion from 1979 to 1992 by approximately a factor of two, despite natio nal increases in motor fuel consumption and the volume of traffic. Rel evant European Community legislation covering emissions from motor-veh icles are outlined and comparisons are made with emissions from motor vehicles predicted from the UK national inventory. The importance of t he frequency of measurements was also noted.