Perspectives on aerosol inhalability: concepts and applications

The original motivation for the aerosol inhalability convention was to account for the fact that the inhalation efficiency of particles can cause the composition of the particle-containing air that is inhaled into the mouth and nose to differ significantly from the composition of the ambient air. Therefore, without appropriate adjustments for the inhalation efficiency of particles, air samples could over- or underestimate the actual exposures of inhaled materials, possibly compromising some workplace air standards. Subsequently, the concepts and applications of inhalability and inhalability sampling have been expanded to inhalation exposures outside of the workplace, including general human populations, medical patients, cell cultures, and animal research subjects. As described in this commentary, some of these applications have occurred in ways that could misrepresent actual exposures. Scientific advances in the understanding and applications of inhalability-related concepts are needed. Such advances will best be achieved through multidisciplinary collaborations involving modeling, wind tunnel mannequin and human subject studies, and health effects studies involving input from aerosol scientists, engineers, physiologists, anatomists, physicians, veterinarians, mathematical modelers, and regulators.