BREATHING 



240. Ventilation of Schoolrooms. Special pains must be 

 taken to ventilate schoolrooms. Pupils are sure to become 

 listless, uneasy, dull, and sleepy when the air is not whole- 

 some. Children may be comfortable in a well-aired room 

 at 66 F., but it is very easy to let the temperature run up 

 to 80, or even above, before it is noticed. 



Whatever apparatus for ventilation may be used, the 

 doors and windows should be opened before and after 

 each session and at recess. 



FIG. 112. 



Two petri dishes: one, A, exposed to the air before, and the other, B, 

 exposed after, a class had occupied a recitation room. Plate A shows 

 few bacteria, while plate B contains large numbers. 



The air of the schoolroom should be changed as often 

 as once every hour. The pupils meanwhile should engage 

 in active gymnastic exercises to prevent taking cold. When 

 this is done in cold weather, the heat should be turned on 

 and the fresh, cold air warmed as quickly as possible. 1 



1 School children sitting at their desks, clerks bending over their ledgers, 

 seamstresses at work with the needle or the sewing machine, stenographers, 

 typewriters, and all who must stoop as they earn their daily bread, should 

 learn to stop from time to time, sit back in the chair or rise, throw back 



