# Page:Popular Science Monthly Volume 81.djvu/394

${\displaystyle {\ce {CO2}}}$ is kept below 2 to 3 per cent, they are capable of carrying out efficient work. In the case of workers in compressed air it is important to bear in mind that the effect of the ${\displaystyle {\ce {CO2}}}$ on the breathing depends on the partial pressure and not on the percentage of this gas in the air breathed.
The sanitarian says it is necessary to keep the ${\displaystyle {\ce {CO2}}}$ below 0.01 per cent., so that the organic poisons may not collect to a harmful extent. The evil smell of crowded rooms is accepted as unequivocal evidence of the existence of such. He pays much attention to this and little or none to the heat and moisture of the air. The smell arises from the secretions of the skin, soiled clothes, etc. The smell is only sensed by and excites disgust in one who comes to it from the outside air. He who is inside and helps to make the "fugg" is both wholly unaware of and unaffected by it. Flügge points out, with justice, that while we naturally avoid any smell that excites disgust and puts us off our appetite, yet the offensive quality of the smell does not prove its poisonous nature. For the smell of the trade or food of one man may be horrible and loathsome to another not used to such.