Natural Ventilation for the Prevention of Airborne Contagion
Figure 3
Ventilation and Protection against Airborne TB Transmission in Old-Fashioned Compared with Modern Rooms
Ventilation and protection against airborne infection is shown for pre-1950 versus modern (1970–1990) naturally ventilated facilities versus mechanically ventilated negative-pressure respiratory isolation rooms. The triplet of bars on the left represents ACH in old-fashioned, high-ceilinged, pre-1950 naturally ventilated clinical areas (n = 22; 201 experiments), versus modern naturally ventilated facilities (n = 42; 125 experiments), versus mechanically ventilated negative-pressure facilities (n = 12). The left-centre triplet of bars represents the same comparison for absolute ventilation (m3/h/100); the right-centre triplet of bars represents that for absolute ventilation per person (m3/h/100); and the triplet of bars on the right that for the estimated risk of airborne TB transmission (percentage of susceptible persons infected), for 24-h exposure to infectious TB patients [17]. Data are shown for 64 naturally ventilated rooms with windows and doors fully open (the remaining six naturally ventilated rooms had windows that could not be fully opened).