The Effect of Chemicals on Microorganisms 207 



spread of upper respiratory diseases via the air. It is surprising 

 to note the many ideal characteristics displayed by these glycols 

 which make them suited for disinfecting air. They have a low 

 toxicitv for man and other animals, are odorless, tasteless, reason- 

 able in price, and are non-irritating. 



Triethylene glycol has been found to be effective for use in 

 isolation wards of hospitals and in military barracks where people 

 are living in close proximity to one another. Some large industrial 

 concerns have found that the incorporation of these vapors and 

 mists in their air-conditioning systems has reduced the number of 

 man-days lost as a result of common colds, particularly in large 

 offices where large numbers of typists and clerks must work in the 

 same room. 



There is no conclusive evidence available that the continued 

 exposure of humans to glycol vapors has any detectable deleterious 

 effect on man. Prolonged exposure of selected laboratory animals 

 to high concentrations of these vapors has resulted in no ill effects. 

 Portable vaporizers may be purchased for use in small rooms. A 

 special glycol-impregnated paper is mechanically drawn over the 

 surface of heated rollers at controlled speeds, and the vapors may 

 disinfect the air in a moderate-sized room in an hour or less. 



CHEMICAL REACTIONS INVOLVED IN DISINFECTION 



It is not the intent of this book to go into the elaborate chemical 

 explanations involved in disinfection, but even with a limited 

 background in chemistry, students should be able to comprehend 

 the general nature of what probably occurs when an organism is 

 subjected to chemical action. It should be borne in mind that a 

 multiple reaction often occurs, and no single response can be at- 

 tributed as the complete explanation for the death of microor- 

 ganisms. 



OXIDATION 



If oxygen is liberated in the chemical reaction, destruction of 

 organisms may take place. This is at least part of the explanation 

 of the killing power of chlorine and of hydrogen peroxide, to 

 mention but two common substances. 



