Investigation of indoor air pollutant dispersion and cross-contamination around a typical high-rise residential building: Wind tunnel tests

The dispersion of air pollutant in complex building environment has become of great concern as more and more people live in large and crowded cities. The present work is aimed at investigating the indoor air pollutant dispersion and possible cross-unit contamination with typical high-rise residential building design in Hong Kong. Experiments were performed in a boundary layer wind tunnel for a 1:30 scale model that represented a 10-story residential building in prototype. Tracer gas, simulating exhausted room air, was continuously released from three different floor levels, and its concentrations on the adjacent and opposite envelope surfaces were measured using fast flame ionization detectors, while the pressure distributions along building facade were also measured and examined under a typical incoming wind profile. By analyzing the pressure and concentration distribution, the risk of air cross-contamination was evaluated under two wind directions. The experiment results illustrated that, in the so-called re-entrance spaces, the pollutant can spread in both vertical directions, not only in the upward direction that was found under buoyancy effect, but also in the downward direction. Furthermore, dispersion can also occur in the horizontal direction, indicating a potential risk of cross-contamination in the horizontal adjacent flats could not be overlooked as well. The study on this physical process is directly useful for the purpose of prevention and control of infectious diseases outbreak in the residential environment. In the long run, the wind tunnel test data will serve to develop computational tools to assist natural ventilation design for high-rise buildings.