Fig. 3

When an individual enters an enclosed room containing normal OR air flow conditions (positive pressure of 0.03 in. H2O and a ventilation system operating at 20 ACH), CO2 exhalation can be detected provided that the individual is moderately active. When a single person paces the OR for 1 h, the amount of CO2 in the room increases by up to approximately 73 ppm. When the active individual becomes seated and performs no physical activity the CO2 level decreases