Attenuation due to Aerosols, It restricts the distance of free space optical communication systems (FSO) and limits
the availability for line -sight terrestrial link. This work is focused on the effect of Aerosols on the FSO link. The
attenuations was studied in the Babylon city in the aerosols phenomena for three selected wavelengths (632.8, 785, and
1330 nm) for horizontal transmitting range (10 m-3 km).The results show the system availability as a function of the
range, and indicate that FSO systems can be deployed with reliability in Babylon city of Iraq. .
Key words: Attenuation, Propagation, Atmospheric Transmittance, FSO.