The technical report was prepared in response to:- growing concern about the potential risks to human health related to occupational exposure to nano-sized and nanoscale aerosol particles (collectively referred to as nanoaerosols, including the subset of particles generated as by-products of industrial processes and generally referred to as ultrafine aerosols);- lack of current guidelines and applicable standards to reduce risks for human health; e- the need to establish effective sampling methodologies as part of the process of formulating appropriate exposure and standards for corresponding monitoring.