This document provides rules for workplace sampling and the sample analysis for the determination and characterization of airborne NOAA for electron microscopy and includes: the choice of appropriate samplers and their use for the determination and characterization (e.g. classification of structures and morphology) of airborne NOAA using electron microscopic methods (SEM and (S)TEM); counting rules and criteria for the determination and characterization (e.g. classification of structures, chemical composition and morphology) of airborne NOAA using electron microscopic methods (SEM and (S)TEM), especially for nanofibres and platelets. This document is based on extensive laboratory tests for airborne NOAA, in particular those released during the handling of engineered nanomaterials.