1930s (Yaglou et al., 1936). Function C in Figure 10–1 is derived from experiments of Yaglou et al. (1936), where judges assessed the odor generated by occupants sitting quietly in an environmental chamber. The function depicts the combination of air space per person and ventilation rate of the air space (outdoor air) per person necessary to maintain odor at a moderate, acceptable level under steady-state conditions. Theoretical functions A and B, which fall below C, implying less need for ventilation, represent the outdoor air needed to maintain oxygen at a minimum of 20% and the air necessary to hold carbon dioxide at a maximum 0.6%, respectively.
The decrease in curve C at low occupancy density (large air space per person) resulted most likely from the instability of occupancy body odor in Yaglou’s chamber. That is, occupancy odor decays relatively rapidly on its own (Yaglou and Witheridge, 1937; Clausen et al., 1984). Tobacco smoke odor, on the other hand, exhibits relative stability. When smoking has ceased in an unventilated room, the odor will remain at the about same level over many hours (Yaglou and Witheridge, 1937; Clausen et al., 1985). In a diagram such as Figure 10–1, a function for tobacco