The theory of resistance and particle capture by fibrous air filters is reviewed, and equations are selected from the literature that allow performance to be predicted for a wide range of operating conditions and filter media types. Particle-size-efficiency test data allow equation parameters to be fitted to improve the accuracy of these predictions. The equations can be used to predict air quality in occupied spaces. However, the properties and generation rates of indoor aerosols must also be known, along with the dust conditions outdoors. Such data are not generally available, hence much study remains before particle-size-efficiency data becomes of much use for general ventilation system design. Standard models for ventilation- filtration systems, and for system parameters, need to be developed.

Units: SI