The effect of portable HEPA filtered air cleaning devices upon residential indoor particulate and allergen concentrations.

People who suffer from airborne respiratory allergies often advised to obtain and rely upon portable HEPA filtered air devices for relief. While this advice may work for some individuals, many allergic people do not experience relief or a lessening of symptoms. For allergic individuals for whom this mitigation strategy is not successful, the manufacturers' claims seem over stated. It is important for the manufacturers, allergists, indoor air quality professionals and allergic individuals to understand when air cleaners would be successful and the parameters that determine their effectiveness. The ability of these devices to benefit allergic residential occupants depends upon the generation rate and particulate characteristics of the allergen, as well as the room ventilation. This paper reviews, airborne allergenic sources and presents a theoretical model for determining the efficacy of HEPA filtered air cleaning devices of various flow rates upon the equilibrium allergen concentration. The model demonstrates the importance of infiltration, settling rate, room dimensions and flow rate upon removal of particulate allergens. The model will assist in determining if a HEPA filtered air cleaning device will be successful in reducing airborne concentrations of specific particulate allergens and in selection of an appropriate size device for varying residential or indoor environments.