Fresh air

 Lack of Fresh Air

Thick curtains, closely drawn around the bed, are very injurious, because they not only confine the effluvia thrown off from our bodies whilst in bed, but interrupt the current of pure air. 

 Fresh Air

Pure atmospheric air is composed of nitrogen, oxygen, and a very  small proportion of carbonic acid gas. Air once breathed has lost the chief part of its oxygen, and acquired a proportionate increase of carbonic acid gas. 

Therefore , health requires that we breathe the same air once only.