Multi-Scale Transport Modeling: Asbestos and Nano Fibers in Inhalation Risk Assessments

Recent rapid development of the carbon nanotubes (CNTs) industry has raised health concerns as these engineered particles have the appearance of asbestos, which is a well-known inhalation hazard. Compared to asbestos, CNTs have similar elongated rod shaped structure, while they are in nano-scale where the particle motion is markedly affected by Brownian diffusion. However, limited studies on Brownian dynamics of CNTs are available in the literature and the details of motions of these elongate ultrafine particles, and in particular, their transport and deposition processes are largely unknown. In this study, multi-scale analysis of transport and deposition of elongated particles in micro and nano-scales were performed. Particular attention was given to the differences and similarities of the physical mechanisms governing the particle/fiber motions at different length scales. The study was focused on revealing the details of the interaction between elongated particles at different scales and the fluid motions. Such information is very useful in understanding the transport processes of asbestos and nano-fibers in human airways for inhalation risk assessment studies.