Abstract
Previous studies have highlighted the importance of vehicles as a contributor to airborne particulate matter. For example, the Quality of Urban Air Review Group described results from a study of urban particulate matter carried out by London Scientific Services (LSS, 1990). This study showed that in central London, roadside levels of particulate matter were 2–3 times higher than at a nearby “urban background” monitoring site, indicating road vehicles as a major contributor to particulate matter. QUARG (1993a) also analysed carbon monoxide and PM10 data for the central London Enhanced Urban Network site for a part of 1992. As a correlation coefficient of only 0.3 was found it was concluded that traffic might be only a minor influence on particulate matter concentrations. It was noted that although there were large day to day variations in PM10 concentration, the variations in traffic activity were relatively small. QUARG concluded that episodes of low rainfall and high windspeed would exert a strong influence on the concentration of particulate matter, as these conditions would lead to much resuspension of deposited dusts.