The growing trend for energy savings has resulted in tightening the building envelope, so the risk of contaminant accumulation and cross contamination is growing. Often, traditional mechanical ventilation systems that are installed in airtight buildings are not efficient in providing the proper amount of fresh air for individuals and do not protect them from cross contamination. Personal ventilation is an alternative to traditional ventilation systems as it provides fresh and purified air directly to the breathing zone. Not only does this method, in many cases, improve the thermal comfort of occupants, but also protects them from cross contamination from other occupants. In this study an air terminal device was tested to see if it would protect the occupant from cross contamination under changing conditions of the flow rate. Different velocities were simulated using the AnsysFluent CFD program, thanks to which the velocity around the occupants face was shown. The chosen velocities were 15 L/s, 10 L/s, 5L/s and 1L/s. The results showed that when the air flow was low, the personal ventilation system may not be effective in protecting against cross contamination.