Flow of microorganisms in a hospital stair shaft - full-scale measurements and mathematical model.

Measurements of air flow and microorganism concentration have been made in the stair shafts of a hospital, using a diving bell-type of pressure-recording instrument, and a sampler for the microorganisms, respectively. Results of experiments were used to calculate the flow rate of microorganisms between the floors of the hospital. A mathematical model based on simplified transport equations is proposed, which would allow the prediction of the flow field and the distribution of microorganisms in the stair shaft. Comparisons between measurements and numerical calculations indicate that the mathematical model is able to predict the global flow field, qualitatively. The application of the numerical method can help to reduce the experimental work, as well as to investigate the complex exchange mechanisms of microorganisms.