Characterization of airborne particulate matter in greater Cairo area (Egypt) studied by neutron activation analysis

Aerosol samples for PM10 were collected by high volume samplers from June 2003 to June 2005 at three aerosol stations located in greater Cairo area in the north south direction. Instrumental Neutron Activation Analysis and total reflection fluorescence analysis (TXRF) techniques were used to measure the concentration of about 35 elements, while a Liquid Chromatography was used to measure ions (SO4, NO3 and NH4). PM10 mass concentrations are generally high through the greater Cairo area. PM10 values obtained for all sampling events at the three monitoring sites are generally high and exceeded the Governmental Egypt's (GOE) Low Number 4 of 1994 limit of 70 μg/m3 (24 hour average). PM10 concentrations maximize in spring associated with sand storms during Khamseen conditions and in autumn with longer duration due to trapping of pollutant emissions within a shallow planetary boundary layer. A number of sources including traffic and also biomass/waste burning contribute to the formation of the pollution episodes. The analysis of PM10 samples has shown wide variation in toxic pollutants. The results reveal that the concentrations of several pollutant elements in dust samples from these three sites are highly variable. Some elements showed a dependence on the day of the week, while others did not. The highest mean concentrations of organic carbon (27.6μg/m3) and elemental carbon (14.8μg/m3) in PM10 were found at Shoubra Kheima among the three sites. The major fractions of sulfate at the three monitoring sites are non sea salts sulfate. The monitoring results suggest that control of particulate matter in greater Cairo area may be a difficult problem