A three-dimensional small-slip model for particle diffusion in turbulent airflows in buildings is presented. The interaction between the carrier air and the particles has been treated as a one-way coupling, assuming the effect of particles on air turbulence is negligible due to very low solid loadings. Turbulent effects are numerically modeled with a standard k-εmodel. The airflow and aerosol particle distribution as well as impact on Indoor Air Environment (IAE) are analyzed with respect to the arrangement of exhaust openings in ceiling under traditional displacement ventilation.