It is believed that clays can control the formation of red tides. Therefore, construction of dams that can reduce the discharge of clays into the marine bodies, may be considered as one of the reasons for the fomation of red tides. Does dust fall control the formation of red tides? In the recent years, due to the lower precipitations, many marshes in middle east region are fully or partially dried. These marshes are now the main source of atmospheric dusts in the region. Sometimes the concentration of such dust particles can reach to as high as 3000 mg/m3.