The behaviour of solid contaminants in air flow is important for identifying those in variouslocations in ventilated space. The main reason for this study is to find out where different-sized particles can be found in a room using a simple particle-settling model. In this investigation two distinctive particle sizes are considered, i.e. 0.5 m and 10 m. Additionally, two different ventilation configurations are used to examine how this influences the particle concentration. To find out the particle mass transferred from several zones defined in the investigated room is one of the central methods to understand on how the particles actually are behaving in the air flow. Preliminary results indicate that particle behaviour is predominantly influenced by air flow structure and particle diameter.