METHODS OF PEEVENTlNG AND SPKEADING DISEASE 323 



Direct Sunlight as a Germicide. Direct sunlight kills the bac- 

 teria that are the cause of most human diseases. Such bacteria 

 do not require air to live, and are known as anaerobic. If it were 

 not for the ability of sunlight to kill dangerous bacteria which are 

 about us everywhere in the open air, the human race might soon 

 become extinct. The winds would carry the diseases from place to 

 place, and no home would be safe from sickness. In the sunlight 

 there are ultra-violet rays, rays of light which do not affect the 

 human eye. Whenever bacteria fall under the influence of these 

 rays in strong sunlight they are killed. Ozone formed by the ultra- 

 violet rays probably also assists in killing bacteria. We know how 

 strong this substance is as it often causes colors to fade in rugs or 

 draperies left in direct sunlight. Physicians are using ultra-violet 

 rays for special treatment in cases of certain diseases. In fact, 

 direct sunlight is the most powerful germicide known. 



QUESTIONS 



1. Why should people not object to quarantine? 



2. Why should all people who are quarantined be glad to obey 

 the rules of the Board of Health? 



3. What is the best way to prevent the transmission of disease? 



4. How do you care for wounds at home? 



5. When should disinfectants be used? 



6. What is the best disinfectant? 



7. Why should all rooms be well lighted? 



8. What care should be taken of badly soiled handkerchiefs? 



9. Why should one wear gloves when traveling? 



10. Why should reservoirs be open at the top? 



11. Why is it well to have a school room so situated that the 

 sun shines directly into the room during a part of the day? 



