The relative efficacy of respirators and room ventilation in preventing occupational tuberculosis.

The study described attempted to assess the relative efficacy of personal respiratory protection when infectious aerosol concentration increases or room ventilation rates decrease. A variable for respirator leakage was added to the Wells-Riley mathematical model of airborne transmission of disease. States that infection risk decreases exponentially with increasing room ventilation or personal respiratory protection. As room ventilation rates increase, or concentrations of infectious aerosols decrease, the relative efficacy of personal respiratory protection decreases. Concludes that the risk of occupational tuberculosis can probably be considerably lowered with the use of relatively simple respirators and modest room ventilation. For exposures to more highly concentrated aerosols, more sophisticated respirators may be needed.