380 RESPIRATION. 



" 1. The immediate dangers from breathing air highly vitiated 

 by respiration arise entirely from the excess of carbon dioxid and 

 deficiency of oxygen, and not from any special poison. 



" 2. The hyperpnea is due to excess of carbon dioxid, and is not 

 appreciably affected by the corresponding deficiency of oxygen. 

 The hyperpnea begins to appear when the carbon dioxid rises to 

 from 3 to 4 per cent. At about 10 per cent, there is extreme 

 distress. 



" 3. Excess of carbon dioxid is likewise the cause, or at least 

 one cause, of the frontal headache produced by highly vitiated 

 air. 



" 4. Hyperpnea from defect of oxygen begins to be appreciable 

 when the oxygen in the air breathed has fallen to a point which 

 seems to differ in different individuals. In one case the hyperp- 

 nea became appreciable at about 12 per cent., and excessive at 

 about 6 per cent." 



Haldane and Smith also regard the odorous substances present 

 in rooms due to a want of cleanliness as contributing to the dis- 

 comfort caused by breathing the air of such rooms. 



It must be remembered that the oxygen of the air is consumed 

 and carbon dioxid and other impurities produced by stoves, gas- 

 burners, and lamps, as well as by respiration. Thus a large gas- 

 burner will in one hour consume as much oxygen as a human 

 being will in five hours, and at the same time will be produced 

 carbon dioxid and monoxid, sulphur compounds, and other gaseous 

 impurities, all of which vitiate the air to a considerable degree. 

 At the same time the air is heated. Perhaps one of the most 

 important advantages which has accrued from the introduction of 

 electricity as applied to illuminating-purposes is the entire absence 

 of heat and of those impurities which so impoverish the air of 

 inhabited rooms. 



It is generally conceded that if the respiratory CO 2 in the air 

 does not exceed 0.02 per cent, above that which is ordinarily 

 present in all air 0.03 or 0.04 per cent. bringing it up to 0.06 

 or 0.07 per cent., no harm will result, and adequate ventilation 

 will be secured i. e., keeping the CO 2 from increasing beyond 

 0.06 or 0.07 per cent. To bring this about will require as. a 

 minimum 60,000 liters (20QO cubic feet) per hour per individual, 

 but this should be increased by at least one-half (making it 3000 

 cubic feet) to provide for the increased production of CO 2 caused 

 by active exercise ; and in factories and workshops where all the 

 operatives are men, and all actively at work, this amount often 

 needs to be as much as 6000 cubic feet. For hospitals, where the 

 emanations from the sick are more likely to vitiate the air than 

 are those from the well, at least 6000 cubic feet should be pro- 

 vided. These figures take no account of gas-burners or lamps, 

 and for these there should be allowed not less than 1800 cubic 



