Deposition of indoor airborne particles onto human body surfaces: A modeling analysis and manikin-based experimental study

Abstract

Aerosol particles deposit onto human body surfaces in indoor environments. However, the relative importance of this pathway is poorly characterized. In this study, an improved three-layer model was developed; it incorporates Brownian and turbulent diffusion, gravitational settling, turbophoresis, thermophoresis, and diffusiophoresis to predict particle deposition velocities onto human body surfaces. The model was preliminarily evaluated with manikin-based experiments, conducted in an 8 m3 stainless steel chamber for particles ranging from 0.01 m to 5 m. Both standing and sitting manikins with heat dissipation ranging from 50 w to 100 w were used. Following comparisons with the experimental results, the model was used to estimate particle deposition velocities onto the body surfaces of standing and sitting humans for three normal scenarios (transition season, summer, and winter). For particles from 0.01 m to 3 m deposition velocities were the highest in summer and the lowest in winter. For particles larger than 3 m the trend was inversed. The modeled results suggest that direct deposition onto human body for particles ranging from about 0.05 m to 0.5 m is a relatively unimportant exposure pathway for standing and sitting human beings. However, for particles smaller than 0.05 m and larger than 0.5 m, direct deposition onto standing and sitting human beings may be an important exposure pathway. Copyright © American Association for Aerosol Research.