Natural Deposition and Removal Efficiency of Bioaerosols in Confined Spaces

In this study, we measure the decay rates of bioaerosols in a confined space under diverse working conditions (i.e. HEPA filtering, closed/open door, and sealed/open AC vents etc.). The results were collected from various sensors placed at different locations and heights, revealing that aerosol concentrations in confined spaces quickly became uniform and concentration decay occurred concurrently at multiple points. Notably, our investigation involved studying four types of aerosols: bioaerosols originating from procedures on extracted human teeth, aerosols from procedures on synthetic teeth, and aerosolized distilled and tap water, allowing for a direct comparison of respective decay rates. The most efficient particle removal method was the use of a HEPA air purifier, following by an extraoral suction device, AC system, and finally natural deposition. Notably, if used during procedures, the extraoral suction resulted in a significant reduction of particles being suspended in the environment, but for comparable aerosol concentrations, a standard HEPA air purifier was more effective at removing aerosols. This multi-particle approach provides valuable insights into the behavior of diverse aerosol types and allows for substitution scenarios for results from previous experiments which used synthetic teeth or aerosolized sprays to assess decay rates and fallow time. Furthermore, we developed a semi-empirical model capable of predicting the decay rates of various bioaerosols under a multitude of environmental scenarios.