Particulate deposition on indoor surfaces - its role with ventilation in indoor air quality prediction.

There is an increasing concern at the possible health effects of fine suspended particulate (aerosol) upon human health, particularly in the urban environment. Aerosol infiltrating indoors may arise from transport, power generation and natural sources. Aerosol also arises from indoor sources, through cooking processes for example, and from animal dander. In zones within a building, within which the air is reasonably well-mixed, the levels of aerosol will depend upon the ventilation rate and the rate of deposition on indoor surfaces. For conditions of low air exchange rate, surface deposition will be the dominant removal process. It will depend upon the nature and orientation of surfaces and on the airflow conditions and is usually expressed in terms of a characteristic deposition velocity. This paper describes a sensitive aerosol labelling technique which allows experiments to be conducted, in both occupied test houses and aerosol test chambers, aimed at measuring aerosol deposition velocities to a range of surface types. Progress is also reported in developing a CFD code capable of making use of the boundary layer parameters which result from the experimental work.