254 Microbes and You 



fashioned" broom and dust cloth technics. Housewives probably 

 inhale fewer bacteria when these vacuum devices are employed. 

 But manufacturers have, at times, used misleading advertising in 

 this regard when they call their machines "air purifiers." The 

 bags in which the dirt is collected vary in their efficiency, and it 

 has been demonstrated that some bacteria are capable of passing 

 through certain bags very rapidly and returning to the air of the 

 room at the exhaust end of the vacuum cleaner. 



Qualitative determinations have revealed that potentially dan- 

 gerous respiratory organisms, particularly streptococci, are quite 

 numerous in the air and dust of military barracks, dormitories, and 

 hospital wards. By oiling the floors and by treating the bedding 

 with oil-containing compounds, such as mineral oil in special 

 emulsifying agents, the air can be protected against high dust 

 counts and therefore against high bacterial counts. This oiling 

 technic has proven satisfactory enough to warrant adoption by 

 both the British and the American armies. When properly applied 

 to bedding, these compounds leave no greasy feeling, no odor or 

 fire hazard. 



In regions where considerable soft coal is ysed as fuel, the 

 smoke belching from the chimneys can fill the surrounding air 

 with high concentrations of dust and chemical vapors which cannot 

 be considered as conducive to good health. While the number of 

 microorganisms in the air of such localities may not be very high, 

 the non-living entities can inflict potential harm over a prolonged 

 period. Especially affected are asthmatics whose condition is 

 aggravated by smog. Various mechanical devices are available 

 for installation in chimneys to precipitate these smoke particles 

 before they are expelled into the atmosphere, and in communities 

 where anti-smoke campaigns have been instituted, such devices are 

 playing an important part in attaining the desired results. 



QUALITATIVE TECHNICS FOR MICROBIOLOGICAL AIR 



ANALYSIS 



One of the simplest approaches to the problem of determining 

 the microbial content of the air is to expose the agar surface of 



