Airborne dust particles originated from sand and gravel quarries: Mineralogical, geochemical, and size distribution constraints on their potential health impacts

Abstract Dust particles derived from sand and gravel mining have been considered as one of the possible sources of suspended particles in Tehran, the capital city of Iran. In this research, the size, morphological, and geochemical characteristics of the airborne particles originated from open mines were investigated. Twenty-two samples from different heights (3 to 21m) were collected from a sand and gravel quarry in Shahriar as the representative of the numerous quarries in western Tehran. The selected samples were further analyzed using X-ray powder diffraction (XRD) and Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM-EDS). The main mineralogy of airborne dust was dominated by quartz, followed by albite and calcite. The size distribution of deposited particles at different heights ranged from 0.05 µm to 100 µm and about 80% of them were respirable (< 10 µm) and available for transfer through the atmosphere. Si/Al ratios fall mainly into a range between 4 and 10. About 80% of the total particles are below 10 µm. Most nanoparticles were settled into agglomerated forms.