61 
Some PRELIMINARY NoTES ON THE HyYGIENIC VALUE oF VARIOUS 
STREET PAVEMENTS AS DETERMINED BY BAo- 
TERIOLOGICAL ANALYSES. 
By SEVERANCE BuRRAGE AND D. B. LUTEN. 
In many of our large cities, and small ones, too, the question of pave- 
ment is a very important one. The government looks largely upon the 
question of economy, the life of the particular pavement being perhaps 
the most important factor in assisting them to a decision for or against it. 
Some pavement companies in pushing their own work, will claim that 
their pavement is more sanitary than this or that one. Have they any 
data, any facts that will permit them to make such statements? It was 
partly for the purpose of settling this question that the foregoing experi- 
ments were undertaken. 
In working on this subject, it has been found that the sanitary or 
hygienic value of a pavement depends almost entirely on its power to col- 
lect, retain or give up dust, although there are other factors, such as 
reflection of heat, etc., that must be considered. But this dust leads to a 
discussion of the point as to whether a strictly sanitary pavement is one 
that will remain moist the longest time, thus holding on to the dust, and 
at the same time, perhaps, permitting the multiplication of bacteria; or 
whether the sanitary pavement is the one that dries the quickest, and with 
the assistance of traffic and the winds, scatters the dried dust broadcast. 
Street dust is always laden with bacteria, and it was thought that 
possibly some bacteriological analyses under different conditions might 
assist in the solution of this problem. It is not necessary to state that 
aside from the bacterial contents of dust, hygienically speaking, it in itself 
is an irritating factor to the mucous membrane of the nose and throat, as 
well as to the delicate membranes of the eye. And thus, without taking 
the bacteria into account at all, the pavement permitting the least dust 
would be regarded as most sanitary. But the bacteria usually occur in 
proportion to the amount of other dust, so the measure for one will serve 
fairly well as an indicator for the amount of inorganic dust. The experi- 
ments herein reported were undertaken on the Lafayette, Indiana, pave- 
ments, including macadam, brick, wood block (not creosoted), and sheet 
asphalt. 
