Monolayer and multilayer particle resuspension from indoor surfaces : literature review and experimental methodology

Resuspension is an important source of particles in the indoor environment. A variable that may have a significant impact on the fraction of particles removed from indoor surfaces is the type of particle deposit. Particles may be deposited in either a monolayer, where there is minimal particle-to-particle contact, or a multilayer, where there is substantial particle-to-particle contact and interaction. This paper provides a review of theoretical and experimental studies on particle resuspension from monolayer and multilayer particle deposits. In addition, an experimental methodology was developed to determine resuspension from the two types of deposits on indoor surfaces. Seeded samples were exposed to controlled flow conditions in a micro-scale wind tunnel and were analyzed with fluorescence stereomicroscopy. Resuspension was found to occur at significantly lower velocities for multilayer deposits compared to monolayer deposits.