NO. 23 INFLUENCE OF ATMOSPHERE ON HEALTH 21 



minutes. We can confirm these findings. High percentages of CO z , 

 for example, 30 to 50 per cent cause spasm of the glottis and cannot 

 be inhaled by the normal individual. 



At each breath we rebreathe into our lungs the air in the nose and 

 large air-tubes (the dead-space air), and about one-third of the air 

 which is breathed in is dead-space air when we are resting. Thus, 

 no man breathes in pure outside air into his lungs, but air con- 

 taminated perhaps by one-third or ( on deep breathing during muscu- 

 lar work) by one-tenth with his own expired air. When a child 

 goes to sleep with its head partly buried under the bed clothes, and 

 in a cradle confined by curtains, it rebreathes the expired air to a 

 still greater extent ; and so with all animals that snuggle together 

 for warmth's sake. Not only the new-born babe sleeping against its 

 mother's breast, but pigs in a sty, young rabbits, rats and mice 

 clustered together in their nests, and young chicks under the brood- 

 ing hen, all alike breathe a far higher percentage than that allowed 

 by the Factory Acts. Cattle in ill-ventilated stalls may breathe 10 

 times the normal percentage * of CO.. 



When the air of a room is still, the expired air may not be blown 

 away and hangs round a person recumbent therein. Thus B. Hey- 

 mann " found 0.44 per cent in the inspired air, against 0.0318 in the 

 air of the room. On putting an electric fan to blow across his face at 

 a rate of 3.3 meters per second the CO., in the inspired air fell to 

 0.0307 per cent. 



To rebreathe one's own breath is a natural and inevitable per- 

 formance, and to breathe some of the air exhaled by another is the 

 common lot of men who, like animals, have to crowd together and 

 husband their heat in fighting the inclemency of the weather. 



Lehmann found in a brewery 1.5 to 2.5 per cent C0 2 in the air of 

 the fermentation rooms. This was breathed by 5 to 8 workers for 

 hours long with no ill effects. All were strong, healthy young men, 

 some having done the work for years. Weak men with affections of 

 the lungs are not allowed to do this form of work. With 11.6 to 

 14.7 per cent most were constrained to leave the room in two minutes, 

 but two strong young men endured it for 5 minutes and were all 

 right afterwards. 



An experiment was made of breathing for three-fourths of an 

 hour 1.8 to 3.5 per cent CO.,, rising finally to 10 per cent, when the 



1 Schultze u. Maercker. Neben den CO^ Gehalt der Stall fult. Gottingen, i86q. 

 Cited after B. Heymann. 

 2 Ztschr. f. Hygiene, Vol. 49, 1905, p. 403. 



