A preliminary apportionment of the sources of ambient PM10, PM2.5, and VOCs in Cairo

Two intensive ambient monitoring studies were carried out in the greater Cairo area during the periods of 21 February–3 March and 29 October–27 November 1999. PM10, PM2.5, PAHs, and VOCs were measured on a 24 h basis at each of six sampling stations. The primary goal of the studies was to determine the sources of the observed high pollutant levels in the greater Cairo area. In addition, the results provide a baseline against which future studies could assess the impact of regulatory initiatives and controls on pollutant levels. High levels of all pollutants were observed during the two intensive measurement periods. For example, the average 24 h PM2.5 concentration in Shobra, an industrial site, was 216 μg/m3 during the February/March 1999 period. High levels of trace metals were also observed, with an average PM2.5 Pb level of 26.8 μg/m3 at the Shobra location. El Qualaly, the site chosen to represent mobile emissions, displayed the highest average NMHC concentrations of any site, by a factor of 2 or more. The CMB receptor model was used to estimate source contributions to the observed PM and VOCs levels. Major contributors to PM10 included geological material, mobile source emissions, and vegetative burning. PM2.5 tended to be dominated by mobile source emissions, vegetative burning, and secondary species. The major contributors to NMHC at all sites were mobile emissions, lead smelting, and liquefied petroleum gas. This paper presents the results of the 21 February–3 March ambient monitoring study along with PM10, PM2.5, and VOC source contribution estimates.