Evaluation of a room for tuberculosis patient isolation using theatrical fog.

OBJECTIVE

To develop a method to evaluate directional airflow patterns, air dilution, and air mixing in facilities where tuberculosis patients are seen.

DESIGN

A tuberculosis patient isolation room was evaluated by analyzing pressure differential between the room and the corridor and by using theatrical fog to visualize room air movement and impact of dilution and exchange, as well as air capture and displacement. Tracer gas was compared to fog results and used to calculate air exchange rates.

SETTING

A small research hospital.

RESULTS

By adding theatrical fog to the patient room at several locations, we quickly learned that most of the air entering the room through the transom and around the door to the corridor was exhausted through the three exhaust vents. Little air appeared to move toward the exhaust fan. For comparison and to confirm the room air exchange rate, tracer gas was distributed and sampled. The kinetics of decay were very similar whether the tracer gas and room air were mixed during sampling or not.

CONCLUSIONS

The fog procedure allowed good visual confirmation of air mixing and airflow patterns and provided quantitative data for evaluating the efficacy of air capture and displacement or dilution and exchange.