Las Vegas optic., 1914-11-10

mosphere breathed. One is constrain-
ed to ask wherein the disagreeable or
detrimental influences of poorly ven
tilated spaces lie. The various phases
OF this vital and timely though not
new subject were discussed some time
ago by qualified experts in a sympos-
ium on ventilation at the Chemists
club In New York city There is una
nifnity among them regarding the pos
sible significance of the chemical viii
alton of the air. Pure air contains
nearly 21 per cent of oxygen. This
may be reduced to II per cent, pro
portion too small even to support or
binary combustion, before its dinlinu-
ton becomes harmful. Except in ex-
treme condition the amount of oxygen
in the closest halls crowded with peo-
pie bradticallS never falls below 20
per tenf Oxygen win, therefore, take
care itself and may probably be
wholly left out OF consideration in
ventilating systems. Indeed, Hender-
son has reminded us that it is neces-
sary to go only short distance up
into, the mountains to come under an
atmospheric pressure as to reduce the
oxygen supply much more than it is
reduced in crowded assemblies, and
yet mountain air is especially health
full. The amount of oxygen in the
air apparently has little or nothing to
do with the stimulating or depressing
properties Of the atmosphere breathed
in ordinary life.
The air, under the usual conditions,
contains about parts of carbon
dioxid per 10000 parts GOA per cent?
and the standard" of desired purity
for the air of dwellings was long
placed as low as parts per 10000.
Experimentation indicates, however,
that it does not become harmful to
man until the carbon dioxid accumu-
lates to above l per cent, or nearly
40 times its usual amount The air
in crowded rooms very rarely reaches
| A per cent, so that evidently quan-
tity of carbon dioxid far exceeding the
highest hygienic limit which has
hitherto been set up as standard
can be breathed with impunity.
The long-debated idea that expired
air contains organic matter whichsis
toxic has been abandoned by most
physiologists. The bacteria in the air
need not be considered, since the com
parative unimportance of the air as a
vehicle for infection is recognized
We may conclude with reasonable GER
tainty that the discomfort in a badly
ventilated place is due to the physical
condition Of the air in respect to tenn
perature, humidity and movement
and not to any chemical properties
The symptoms noted in closed, crowd
ed rooms -restlessness, headache, diz
ziness, nausea, etc.-are to be attrib
uted to heat retention Overheatine
is the chief evil to be guarded against
in ventilation at present. The CHIEF
danger Of our torrid summer days is
not the heat alone, but the combined
heat and humidity; it is the same
factors which are responsible for the
evil effects of the confined air Of
rooms. There is no doubt that the air
of our American living rooms and
many school rooms and other assem-
bly, chambers is kept too warm
Further investigations of the condi
tions actually existing in the midst OF
what is assumed to be inadequate ven
tilation are called for, according to
The Journal Of the American Medical
Assertion. The extraordinary thing
about the shifting practices in the
ventilation of public buildings is that
sweeping conclusions and far reaching
changes in policy have been arrived
at without any detailed or systematic
study such as seems essential in order
to establish a safe basis for action
-O--