This European Standard provides the methodology for measuring and characterizing 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 small 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 dustiness mass fraction, 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 size distribution of the released aerosol in the size range from about 10 nm to 10 µm, d) the quantification of the initial dustiness emission rate and the time to reach 50 % of the total particle number released during testing, and e) the characterization of the aerosol from its particle size distribution and the morphology and chemical composition of its particles. 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 particle number and emission rate has been established for powder dustiness. Eventually, when a large number of measurement data has been obtained, the intention is to revise the European Standard and to introduce such a classification scheme, if applicable. NOTE 2 The small rotating drum method has been applied to test the dustiness of a range of materials including nanoparticle oxides, nanoflakes, organoclays, clays, carbon black, graphite, carbon nanotubes, organic pigments, and pharmaceutical active ingredients. The method has thereby been proven to enable testing of a many different materials that can contain nanomaterials as the main component.