A hospital is a place where we find simultaneously people whose health state is weakened, or vulnerable, and pathogenic microorganisms able to worsen their health. The quality of the air in a hospital must be in conformity with precise criteria in such buildings in everyday usage, and in particular in the areas of the buildings where some risks of specific pollution exist such as in operating rooms. In this paper, we present a modelisation and three dimensional numerical studies made in an operating room. Results could be used when new operating rooms must be conceived or others existing will be modified. It could be used to avoid risks and to allow all controls of any risks. The air flow modelling aim, by analysing the stream coherence, is to control the contamination in the operating area by bringing out the contamination generated within the operating room. It will allow a clear understanding of the complex coupled phenomena thanks to animation and to virtual 3D reality. The use of real data of the studied operating room (geometry, volume, extracted and blown air flow, temperature and hygrometry) will allow to determine the drainage of air, the distribution of temperature, and the zones of poor air distribution. To be able to find the exact distribution zones of the contaminants, the chosen turbulence model has to be accurate with a good ability to predict the recirculation of the air. The obtained results show that only one of the four tested models can correctly define the recirculation of the air.