Free space optical (FSO) communication systems are affected by dust particles suspended in the atmosphere in arid and semi-arid regions. The presence of these particles in the air severely affects the optical link, reduces its availability and causes service outage. In the literature, the effect of dust on the microwave signals has been widely investigated. However, for FSO communication systems that exploit shorter wavelengths, information and research is still very limited yet almost inexistent. Therefore, in this paper, we investigate the performance of FSO links under dust storms. We designed a chamber to emulate this specific environment and carry out measurements. From the experimental investigations, we derive and propose an empirical model for the signal attenuation as a function of the visibility range. The results show acceptable performance for FSO links, under moderate and light dust, with potential reach distance of hundreds of meters to few kilometers. Furthermore, a comparison analysis shows that the dust induces 7 times higher attenuation than fog.