Historical QOD 3/17/2009: True or False: In building fires, the vertical and horizontal dispersion of toxic gases has been found to be relatively uniform.
False. Concentrations of toxic gasses in fires are indeed relatively constant at a given height over surprisingly long distances from the origin of the fire but are significantly lower in the lower half of a given vertical cross-section of a burning corridor. The time needed to achieve maximal concentrations is also lower in the upper zone of heated air.
(J Fire Sciences, 2008 Jan, 268(1).45 [18 pages])
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