**6.1 Optical transmittance of (HP) and (AD) dust**

Concerning the dust of the Agadir-Morocco site, the variations of the optical transmittance T(%) with the Wavelength, measured by the spectrophotometer JASCO V-730 for the samples dust collected from the two areas (HP and AD) are presented in **Figure 9**.

In this section, an amount of dust of 1.75 g/m<sup>2</sup> , 3.45 g/m<sup>2</sup> , 6.77 g/m2 , was collected from the two areas previously mentioned. The type of soil in the Adrar area (AD) is different from the type of soil in the Halieutic-Park area (HP). These results show the impact of soiling on the optical transmittance. A net drop off in the optical transmittance is observed depending on the origin of dust.
