dust 

in atmospheric chemistry
https://doi.org/10.1351/goldbook.D01867
Small, dry, solid particles projected into the air by natural forces, such as wind, volcanic eruption and by mechanical or man-made processes such as crushing, grinding, milling, drilling, demolition, shoveling, conveying, screening, bagging and sweeping. Dust particles are usually in the size range from about 1100 μm in diameter and they settle slowly under the influence of gravity.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2185 [Terms] [Paper]