The handling of dispersed solids may lead to undesirable release of particles. Size and quantity of the particles transferred into the gas depend on the holding and separating forces in the powder. These in turn are determined by characteristic parameters of the powder and of the process. Analogous to the fractional collection efficiency describing the dust separation, a fractional release rate to quantify the release of dust is introduced. The application is demonstrated by an example and the way to further development of this new approach is demonstrated.