This European Standard provides guidelines to assess inhalation exposure to nano-objects and their agglomerates and aggregates (NOAA) as well as to evaluate the results of the assessment either as stand-alone assessment or embedded in a tiered approach framework. While the focus of this European Standard is on the assessment of nano-objects, the approach is also applicable for exposure to the associated agglomerates and aggregates, i.e. NOAA, and particles released from nano composites and nano-enabled products.