Mould spores and metabolites can be inhaled via the air and cause allergic and irritating reactions and/or complex symptoms in humans. Increased concentrations of these compounds are considered a potential health risk. Moreover, mould growth may be associated with severe odour nuisances. This part of EN ISO 16000 provides assistance for the sampling strategy for suitable sampling and analysis methods together with a description of the applicability and the interpretation of the measurement results to maximize the comparability of the measured data obtained for a given measurement objective. Details on field inspections by qualified professionals which have to take place prior to any microbiological measurement are described. Depending on the analysis method mould spores are determined individually or as spore aggregate. Materials, indoor air and house dust will not only contain culturable but also non-culturable mould spores, some of which may have the same allergenic and toxic effects as culturable spores. For this reason, techniques have been developed which allow the microscopic determination of both culturable and non-culturable moulds. The sampling methods employed for detection of moulds are determined by the objective of the investigation (DIN ISO 16000-16 "Filtration" or DIN ISO 16000-18 "Impaction"). Depending on the sampling method, the moulds will suffer a sampling stress during sample collection and preparation, which may lead to their drying-out or dying. Mould detection and differentiation are performed either after cultivation based on morphological criteria, biochemical reactions and/or molecular techniques or by direct microscopic examination (DIN ISO 16000-17).