A model to simulate the particle concentration and size distribution of indoor air and to evaluate the exposure of occupants.

A mathematical model was constructed to simulate time dependent particle concentration inindoor air and to evaluate the exposure of occupants. The model consists of three main parts:(1) a system model to describe the ventilation system and building envelope, (2) a multizone room model, and (3) a dose model. Models (1) and (2) are coded with Neutral Model Format and solved in the IDA simulation environment, and Model (3) in LUDEP (LUng Dose Evaluation Program). Particle deposition mechanisms were formulated with well-known equations. The particle emission from indoor sources and outdoors particle concentration were determined according to the literature and the measured data, respectively. The particles were characterized into three size modes: ultrafine (0.01 m and 0.05 m), fine (0.1 m, 0.4 m and 1 m), and coarse (2.5 m and 5 m).