Validation of RegCM-CHEM4 model by comparison with surface measurements in the Greater Cairo (Egypt) megacity.

The densely populated Greater Cairo (GC) region suffers from severe air quality issues caused by high levels of anthropogenic activities, such as motorized traffic, industries, and agricultural biomass burning events, along with natural sources of particulate matter, such as wind erosion of arid surfaces. Surface-measured concentrations of particulate matter (PM), sulfur dioxide (SO), and ozone (O) and its precursor's gases (nitrogen dioxide, NO; carbon monoxide, CO) were obtained for the GC region. The PM concentrations were found to exceed remarkably the Egyptian guidelines (150 μg/m).