Abstract

Exposure to high levels of particulate matter (PM) has been occurred during severe weather and normal conditions at urban environment. Suspended dust and its viable fraction and smoke concentrations were detected over Cairo during severe weather and normal conditions. During smog episodes, smoke and suspended dust were detected at mean values of 276 µgm³ and 347 µgm³, respectively, whereas during winter dust storm they were detected at mean values of 117.5 µgm and 1074 µgm³ (time weighed average) for the corresponding pollutants, respectively. Surprisingly, during normal conditions smoke was recorded at mean value of 199 µgm³ that exceeded the limit value of smoke recommended by the Egyptian environmental law No 4 (150 µgm³ / 24hrs), whereas suspended dust was detected at mean value of 185.9 µgm³ that was lower than the limit value recommended by the Egyptian environmental law (230 µgm³/24hrs). Sulphates and nitrates were recorded at higher mean values during smog episode and normal conditions than those recorded during winter storm. The lowest culturable viable fraction associated with suspended dust, including environment /bacteria, fungi and streptomycetes was recorded during smog episodes, whereas the highest viable fraction was recorded during winter dust storm. Daily exposure to air pollution depresses immune system and increases of airway responsiveness to aeroallergens.