A health risk assessment study conducted in 1994 for the Greater Cairo (GC) area evaluated the environmental health risks to Cairo residents and determined the major health hazards of ambient lead and particulate matter. In order to determine the spatial and temporal trends in the concentration of these substances, the Egyptian environmental affairs agency (EEAA) decided to initiate a pollutant monitoring program. This was conducted with the help of the USA and Denmark. Numerous monitoring sites were established in Egypt. These sites monitored ambient particulate matter (PM10 and ) and lead through the Cairo air improvement project (CAIP) funded by USAID. In addition, measurements of SO2, NO2, CO, and O3 were performed through the Egyptian information and monitoring program (EIMP) funded by DANIDA. This paper describes the ambient particulate matter and lead levels over a period from 1998 through 2007 for the all monitoring sites in GC. In addition, discussions of the sources of the observed pollutants are presented. | Assessment of particulate matter and lead levels in the Greater Cairo area for the period 1998–2007