This European Standard provides the methodology for measuring the dustiness of bulk materials that contain or release nano-objects or submicrometer particles, under standard and reproducible conditions and specifies for that purpose the rotating drum method. In addition, this European Standard specifies the selection of instruments and devices and the procedures for calculating and presenting the results. It also gives guidelines on the evaluation and reporting of the data. The methodology described in this European Standard enables a) the measurement of the respirable, thoracic and inhalable dustiness mass fractions, b) the measurement of the number-based dustiness index of respirable particles in the size range from about 10 nm to 1 000 nm, c) the measurement of the number-based emission rate of respirable particles in the size range from about 10 nm to 1 000 nm, d) the measurement of the number-based size distribution of the released aerosol in the size range from about 10 nm to 10 µm, and e) the collection of released airborne particles in the respirable fraction for subsequent observations and analysis by analytical electron microscopy. This European Standard is applicable to the testing of a wide range of bulk materials including powders, granules or pellets containing or releasing nano-objects or submicrometer particles in either unbound, bound uncoated and coated forms. NOTE 1 Currently no number-based classification scheme in terms of dustiness indices or emission rates have been established. Eventually, when a large number of measurement data has been obtained, the intention is to revise this European Standard and to introduce such a classification scheme, if applicable. NOTE 2 The method specified in this European Standard has not been investigated for the measurement of the dustiness of bulk materials containing nanofibres and nanoplates in terms of number-based dustiness indices or emission rates. However, there is no reason to believe that the number-based dustiness indices or emission rates could not be measured with the rotating drum using the set-up described in this European Standard.