Reliable aerosol data are required to assist in the safety assessments of nuclear plants. Studies have been undertaken to quantify the form of any airborne radioactive debris released from a wide range of nuclear facilities involving fuel fabrication, reprocessing, and waste management. Furthermore, safety assessments require some knowledge of the aerosols that could be generated as a consequence of hypothetical severe accidents. Conditions within the industrial plant may not be conducive to standard aerosol sampling procedures, while simulant and irradiated fuel studies of reactor accidents may require experiments to be conducted over a wide range of temperatures and pressures. The aerosols predicted to form in thermal light water reactor accidents could be generated at high temperatures and pressures in the presence of steam, while the sodium metal coolant of fast breeder reactors could burn to form dense clouds of aerosol affecting the transport of any fuel debris released from the damaged core. Such factors limit the number of aerosol sampling and analysis techniques that can be successfully used in such studies, and care has to be taken in choosing the most appropriate analytical techniques. The methods used to measure the physical properties of nuclear aerosols are highlighted. The merits and disadvantages of each method are discussed, and guidelines are provided for future developments.