The sun disappeared and the day turned into a scary darkness! Terrible dust storm hits Riyadh, Saudi. Increased concern about the impact of dust storms on air-quality and public health has occurred in recent years. The primary goal of this study is to carry out a comprehensive characterization of falling dust and provide the scientific background for the further control of air pollution at Riyadh during (January-March) months. To characterize the ambient falling dust pollution 15 typical sampling sites were chosen for falling dust collection at time interval of one month. Results revealed that Riyadh city, the capital of Saudi Arabia receives a considerable amount of dust during the studied period. The finding indicated that dust deposition rates across the city are high with sites located near construction activities and those located in Eastern Riyadh being the worst affected. The average monthly deposition value for all sites in the three months ranged from 20.13 to 139.9 Tons km-2 with an average monthly value of 42.09 Tons km-2. The results showed that silt was the dominant fraction in almost all of the dust samples. pH, EC and CaCO3 content were rather high.
