Distribution of annual mean SO 2 concentrations in µg/m 3 calculated with POLAIR dispersion model using (2004) SO 2 concentrations from the national monitoring network at Abassyia site

Distribution of SO 2 concentrations over shooting (150 µg/m 3 per 24 hours) calculated with POLAIR dispersion model using (2004) SO 2 concentrations from the national monitoring network at Abassyia site

Distribution of SO 2 concentrations over shooting (150 µg/m 3 per 24 hours) calculated with POLAIR dispersion model using (2004) SO 2 concentrations from the national monitoring network at Qualaly site

Annual mean SO 2 : observations versus predictions at some monitoring sites in Greater Cairo during 2004

Model performance across distances far from the monitoring stations Distribution of SO 2 concentrations in µg/m 3 calculated with POLAIR dispersion model using (January, June, 2006) SO 2 concentrations from the national monitoring network at Abassyia site

SO2 POLAIR dispersion model Performance results across different distances far from Abassyia Monitoring site using passive samplers Model Accuracy% Mean calculated conc. ( µ g/m 3 ) Mean observed conc. ( µ g/m 3 ) Location description 82% m far from the station Ain Shams University 79% m far from the station Misr Tourist Tower 80% m far from the station Salah Salm Road Military Academy

Distribution of SO 2 concentrations in µg/m 3 calculated with POLAIR dispersion model using (January, June, 2006) SO 2 concentrations from the national monitoring network at Qulaly site

SO 2 POLAIR dispersion model Performance results across different distances far from Qulaly Monitoring site using passive samplers Model Accuracy% Mean calculated conc. (µg/m 3 ) Mean observed conc. (µg/m 3 ) Location description 87% m far from the station High Court 86% m far from the station Maaroof Street

SO 2 POLAIR dispersion model Performance results across different distances far from Maadi Monitoring site using passive samplers Model Accuracy% Mean calculated conc. (µg/m 3 ) Mean observed conc. (µg/m 3 ) Location description 80% m far from the station Misr Helwan Road 81% m far from the station Road % m far from the station Midan al Hurriya

The overall model performance of SO 2 is well performed compared with the actual observed monitoring data. The model calculated SO 2 concentrations closely match observations particularly in the rural residential sites (10th Ramadan) by over prediction of only 8%. SO 2 is under predicted in the northern area described as urban industrial and residential sites (Shoubra El Khemia and Abassyia) by 34% and 13% respectively. The model slightly shows an over prediction for SO 2 in Cairo street canyon areas (Qulaly and Gomohria) by 24% and 21 respectively, also in residential areas (Maddi) is over predicted by 25%.

Although the model results for SO 2 concentration prediction appears to over estimate considerably the majority of the observed SO 2 concentration for the urban and suburban sites, it under estimates SO 2 concentration for down town street canyon areas and industrial areas. The model performance appears much better in rural background sites against the urban sites. The model performance shows an accuracy of 90%.