A Computational Fluid Dynamics (CFD) model for exposure calculations was developed for an occupant in a typical office cubicle. A commercial CFD code was employed, along with the widely-used and readily accessible k-ε turbulence model. By simplifying the seated occupant model to an assembly of simple blocks representing the torso, thighs and legs, it was possible to simulate a realistic cubicle and its occupant with an intermediate grid of ∼100,000 structured cells. This allowed the model to run on a single high-end PC, and made it a practical alternative to the well-mixed zonal models that ignore spatial gradients. The model was used to study the effect of realistic office cubicle environments with multiple emitting surfaces (e.g., panel partitions, desks, carpet, computer), and the occupant in different positions. The effects of four important factors on the normalized breathing zone contaminant concentration were analyzed: 1) the effect of various manikin representations, 2) the effect of various supply diffuser locations, 3) the effect of shifting the manikin (left, right and back), and 4) the effect of the manikin orientation (facing computer and facing wall). The present CFD model indicates that the spatial non-uniformities, even in a room ventilated with a mixing-ventilation system, could result in as much as 45% difference in exposure compared with the calculations based on the simpler, well-mixed assumption. Furthermore, the results of the present model could be used to correct the predictions of the simpler well-mixed, zonal models for spatial non-uniformities, and for the effects of the person's position within the cubicle or the supply diffuser location. This would allow a higher-fidelity assessment of exposure in the office environment. The simple CFD approach is particularly valuable for exposure assessment with displacement and personal ventilation systems, which produce steeper gradients in velocity∼ temperature and concentration within the occupied space.