This document describes the methodology for measuring and characterizing the dustiness of bulk materials that contain or release respirable NOAA or other respirable particles, under standard and reproducible conditions and specifies for that purpose the vortex shaker method. This document 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 document enables a) the measurement of the respirable dustiness mass fraction, b) the measurement of the number-based dustiness index of respirable particles in the particle size range from about 10 nm to about 1 µm, c) the measurement of the number-based emission rate of respirable particles in the particle size range from about 10 nm to about 1 µm, d) the measurement of the number-based particle size distribution of the released respirable aerosol in the particle size range from about 10 nm to 10 µm, e) the collection of released airborne particles in the respirable fraction for subsequent observations and analysis by electron microscopy. This document is applicable to the testing of a wide range of bulk materials including nanomaterials in powder form.