It has long been the custom of hygienists to insist that ventilation or perflation of crowded rooms is necessary in order to remove poisonous emanations arising from the human body. More than twenty years ago, however, observations made to determine the nature of the alleged poisonous properties of the expired air and of “crowd poison” led to negative results. No toxic organic constituent could be demonstrated in the air of crowded rooms, and as for the carbon dioxid, it was so relatively slight in amount that it could not be held responsible for the physiological effects observed, and could at most be regarded as “a measure of danger.” To what, then, are due the disagreeable consequences of remaining in an overcrowded, poorly ventilated room? There can be no doubt that such consequences are real and not imaginary, and that they range all the way from slight depression and headache to severe nausea, vomiting and collapse.
HEATING AND VENTILATION. JAMA. 2011;306(11):1269. doi:10.1001/jama.2011.1210