in atmospheric chemistry
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 1-100 ┬Ám in diameter and they settle slowly under the influence of gravity.
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2185 (https://doi.org/10.1351/pac199062112167)