Experimental investigation and modelling of human-walking-induced particle resuspension

Abstract

Long-term exposure to airborne particulate matter (PM) indoors can cause adverse health effects to the occupants. Such exposure can be influenced by human-walking-induced particle resuspension (HWIPR). Several factors affecting HWIPR were investigated experimentally. The resuspension rates during walking were calculated based on the mass balance model, and the power law was applied to fit the resuspension rate data. The resuspension rate was further normalized for investigating the effects of various factors on HWIPR. It was found that the normalized resuspension rate of PM10 was about 2.5 times that of PM2.5 for both carpet and wood polyvinyl chloride (PVC). The normalized resuspension rate from carpet was about twice as much as the rates from wood PVC and four times that from vinyl. For both carpet and vinyl, the resuspension rates under the low relative humidity (RH) (41%) were three times that under the medium RH (63%) and 3.5 times that under the high RH (82%). The experimental results suggest that the addition of the mechanical mechanism is critical for HWIPR. Based on the power law relationship, an airborne particle concentration model was developed for HWIPR. The modelled concentration profiles were consistent with the experimentally determined particle concentrations associated with HWIPR. The proposed airborne particle concentration model provides a new way of predicting human exposure to airborne particles due to HWIPR.

A Risk Assessment Scheme of Infection Transmission Indoors Incorporating the Impact of Resuspension

“…WIPR is considered by this work as another resuspension scenario. It has been shown that the variation of resuspension rate with respect to time for WIPR could be reasonably described by a power law function: where a r depends on the factors such as walking strength, particle surface loading, relative humidity (RH), resuspension area, and flooring material …”

“…A HEPA filter was installed upon the chamber ventilation and the outdoor airborne particles did not enter the chamber during the measurements. The test dust was seeded onto the carpet to a mass concentration of 20 g/m 2 based on which the number concentrations of 2–3 μm and 4–5 μm particles can be estimated based on the size distribution of test dust and the particle density (2650 kg/m 3 ) . The surface mass concentrations for 2–3 μm and 4–5 μm particles are (20 × 0.13 = 2.6 g/m 2 ) and (20 × 0.2 = 4 g/m 2 ), respectively.…”

“…The particle resuspension area is 5.95 m 2 . To determine the resuspension rate for the WIPR, the resuspension rate [] of the carpet/PM 10 case at the walking rate of 132 steps/min under the RH of 82% in the study of You and Wan is used as the reference. In the reference case, the resuspension area is 0.2 m 2 and the surface mass concentration is 1.75 g/m 2 .…”

“…The power law coefficient ( a r ) of resuspension rate is proportional to the resuspension area and particle surface concentration. Based on the study of You and Wan, the normalized resuspension rate under the RH of 31.7% is assumed to be 5–6 times of that under the RH of 82%. The normalized resuspension rate of PM 10 was about 2.5 times of PM 2.5 and resuspension is more significant for larger particles .…”

“…Based on the study of You and Wan, the normalized resuspension rate under the RH of 31.7% is assumed to be 5–6 times of that under the RH of 82%. The normalized resuspension rate of PM 10 was about 2.5 times of PM 2.5 and resuspension is more significant for larger particles . It is assumed that the normalized resuspension rates for the cases of 2–3 μm and 4–5 μm particles are (0.4–0.6) and (0.8–1.0) times that of PM 10 , respectively.…”