eee ae 
1914] 
NOLTE—SALIVARY ORGANISMS AND AIR POLLUTION 65 
classification? Іп lieu of a definite standard let us assume the 
following table!: 
TABLE V 
PRESUMPTIVE TEST FOR B. COLI IN WATER 
BE quam oor | 01 | 10 | 100 | 100 
Safe O О О О 
Reasonably safe О О о + -- 
Questionable O O -- = + 
Probably unsafe О + + + - 
Unsafe ud ue БЕ + + 
+ indicates positive presumptive test for B. coli. 
We shall now endeavor to prepare a similar table for the purity 
of air, expressed in the number of salivary cocci present in given 
volumes. In the normal life processes, the volume of air inhaled 
is obviously much greater than the volume of water consumed, 
and this fact must be taken into consideration in establishing 
a criterion for the bacteriological examination of air. It has 
been estimated that the tidal air, i.e., the air taken in with each 
inspiration and given out with each expiration, amounts, in a 
normal adult when at rest, to one-half liter. Assuming the 
average frequency of respiration to be 15 per minute, the amount 
of air inhaled in one minute is 74 liters, in one hour, 450 liters, 
and in one day, at least 10,000 liters. Taking the average 
amount of unboiled water drunk in a day as 2 liters, it would 
appear that 5,000 times as much air as water is required daily. 
Hence, the following table, based on table v, may be used to. 
express the sanitary quality of air: 
! Whipple, С. C. On the practical value of presumptive tests for B. coli in 
water. Techn. Quart. 16:18 e. m. 31. 1903. 
