THE RESPIRATORY SYSTEM 125 



neither of these gases can be used to measure the suitability of 

 air for breathing purposes. Bad air is too hot, too humid, has 

 a bad odor, and is still; good air is moderately cool, moderately 

 dry, has no odor, and is in motion. The best temperature of 

 air for breathing is around 50°F. and the most satisfactory 

 humidity 50 to 60 per cent. 



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