BACTERIA IN SOIL, AIR, WATER, AND MILK 201 
Bacteria of the Air 
In the early clays of surgery, it was thought that in¬ 
fection was caused mainly through the air. Working 
upon this principle antiseptic sprays were used. Later 
sterilizing instruments, gloves, clothing, etc., and keep¬ 
ing the air free from dust as much as possible was in¬ 
stituted. Sprays were then discontinued. 
All infection does not come through the air, yet it is 
the means of spreading some diseases. Microorganisms 
being so small and light are by any draft or sweeping, 
disturbed, and suspended in the air. In coming to rest, 
if they chance upon a suitable media, they thrive, and 
infection occurs. 
The air in a crowded room is filled with bacteria, like¬ 
wise the air in the open contains more organisms on a 
dry, windy day, than in moist weather. To lessen con¬ 
tamination from the air, laboratories and operating 
room should be free from drafts. As an added precau¬ 
tion, to prevent the exhaled breath from blowing organ¬ 
isms in the air, many surgeons breathe through gauze 
mouthpieces. When bacteria are found in the air they 
usually exist as spores and molds. Living tubercle 
bacilli have been found in the air after sweeping the room 
where tuberculous patients live. Anthrax bacilli have 
been isolated from the air which surrounds the stable 
of an animal suffering from that disease. 
Smallpox, measles, influenza, scarlet fever, and other 
diseases of unknown origin are sometimes called air¬ 
borne diseases. This term should not be taken literally, 
as “water-borne” diseases is, for the organisms causing 
these illnesses do not live in the air, but are only sus¬ 
pended or carried by it. They are picked up from 
dry sputum or pustules, or sent in the air by sneezing 
or coughing. 
