This document specifies the standard reference method (SRM) for the measurement of low dust concentration in ducted gaseous streams in the concentrations below 50 mg/m3 at standard conditions. This document is primarily developed and validated for gaseous streams emitted by waste incinerators. More generally, it can be applied to gases emitted from other stationary sources, and to higher concentrations. If the gases contain unstable, reactive or semi-volatile substances, the measurement depends on the sampling and filter treatment conditions. This method has been validated in field tests with special emphasis to dust concentrations around 5 mg/m3. The results of the field tests are presented in Annex A.