This International Standard specifies a standard reference method for the determination of PM10 and PM2,5 mass concentrations at stationary emission sources by use of two-stage inpactors. The measurement method is especially suitable for measurements of mass concentrations below 50 mg/m3 as half-hourly averages at standard conditions (273 K, 1013 hPa, dry gas). It is an acceptable method for the measurement in the flue gas of different installations such as cement and steel production as well as combustion processes. This International Standard is not applicable to sampling of flue gases that are saturated with water-vapour. This International Standard is not applicable where the majority of the particles are likely to exceed PM10 e. g. in case of raw gases or plant operating failures. This International Standard may not be used for the determination of the total mass concentration of dust.