AIR
CONSTITUENTS OF AIR
Air is a mixture of gases, not a chemical compound, which envelops
the earth and it is estimated to be at least one hundred miles high.
This gaseous envelope is known as the atmosphere. The water upon
the earth’s surface is called the aquasphere. The solid substance
composing the earth is known as the petrosphere.
Air performs a very important function in the interchanging of gases
in respiration and in the regulation of bodily temperature. The gases
contained in the atmosphere are given by most authorities in the
following proportions, per volume:
Oxygen 20.93%
Nitrogen 78.10%
Argon 0.94%
Carbon Dioxide 0.03%
With traces of helium, krypton, neon, xenon, hydrogen, ammonia,
ozone and hydrogen peroxide.
It is also found that there is a varying amount of water in the air,
as well as dust and other substances. It is worthy of note that the
air maintains a wonderful uniformity of composition over the entire
surface of the earth. This is undoubtedly due to the fact that the
atmosphere is in constant motion which maintains its proper mixture.
It must also be noted that the air is not a chemical compound but is
a mixture of gases.
Oxygen (O)
Probably the most important element in air is the oxygen which
represents about one-fifth of its composition. This percentage is
maintained with very slight variation; for instance, the percentage
of oxygen in towns will be slightly less than 20.93%, about 20.87%.
When the atmosphere contains only 11% or 12% of oxygen it becomes
dangerous, and death results when the percentage gets as low as 7.2%.
A candle will not burn with the oxygen at 16%. Slight variation in
the amount of oxygen is of no special importance.
The amount of oxygen in the air has little to do with the amount
absorbed in respiration, as this is governed more by the need of the
body than by the amount taken into the lungs.
Nature has made a wonderful provision in the protection of the
body from extreme changes in the amount of oxygen in the air. This
provision increases the degree of intellectual adaptation which is
possible in the body. This is shown by the fact that there is a
larger amount of oxygen contained at all times in the lungs than is
required to supply the red blood cells. It is maintained that the
alveolar air contains normally 16% of oxygen. The red blood cells are
practically saturated with oxygen as they leave the lungs; however,
this amount of oxygen may not be needed by the tissue cells which the
red blood cells supply and the amount they absorb upon their return
will depend upon what they have given off to the tissue cells.
It can readily be seen that the air in the lungs at no time contains
the full percentage of oxygen, since one at no time completely
exhales the entire amount of air. In this way the residual air loses
some of its oxygen and collects carbon dioxide.
Animal life is sustained by the oxygen in the air while the carbon
dioxide is essential to plant life. The oxygen is carried into the
lungs during the inhalation which is produced by the expression of
Innate Intelligence through the organs of respiration. The oxygen
passes into the blood and is combined loosely with the hemoglobin of
the red blood corpuscles; then under the direction of Innate it is
carried to all the tissue cells of the body. Here the oxygen leaves
the blood and is used in the oxidation which is necessary in the
metabolism of the body.
The amount of required oxygen varies with different conditions that
obtain in the body and is dependent upon age, the activity of the
individual and his condition of health. Some authors assert that
the average person will inhale about thirty-four pounds of air in
twenty-four hours. This would mean a little over seven pounds of
oxygen. Only about one-fourth of the oxygen inhaled is absorbed;
therefore, according to these figures the individual would absorb on
an average of about two pounds of oxygen in twenty-four hours.
Nitrogen (N)
The nitrogen in the air is of more importance to plant life than to
animal life. It is of little significance from a hygienic standpoint,
yet it is an important constituent of all matter containing protein.
Nitrogen tends to regulate or influence the rate of combustion
by diluting the oxygen in the air. Respiration does not seem to
affect the amount of nitrogen in the air as there is no noticeable
difference between the amount of nitrogen in the inspired and expired
air.
Argon (A)
In 1894 Lord Rayleigh and Prof. William Ramsay discovered a gaseous
substance in the atmosphere which had no chemical affinity. They gave
this element the name argon which means in the Greek, “inactive.” So
far as is known argon will not combine with any other element.
The atmosphere contains about 0.94% argon, but so far, according
to Rosenau, it has not been demonstrated in the body. Argon has no
hygienic significance. Helium, krypton, xenon, neon and argon form
what is known as the =argon group=, since they will not unite with
other elements to form compounds. These elements are all found in
very small quantities in the atmosphere.
Carbon Dioxide (CO_{2})
Carbon dioxide is a gas, a very small amount of which is found in the
atmosphere. About 0.03% is ordinarily expressed. This means there are
three parts of carbon dioxide in 10,000 parts of atmosphere. This is
a very small percentage, but when we consider the enormous bulk of
atmosphere we appreciate the fact that the total amount is beyond
our comprehension. It is claimed that there is more carbon in the
atmosphere in the form of carbon dioxide than there is in all other
forms on the earth.
In densely populated areas there is a slight increase in the amount
of carbon dioxide. It may reach 0.04% or even 0.05%. There is also
likely to be more carbon dioxide in the air close to the soil than
there is a few feet above. This is because the processes going on in
the soil tend to produce this gas and hence the soil air contains
a larger percentage. The air receives its carbon dioxide from such
sources as respiration, fermentation, from chemical action in the
soil, from mineral springs, and from oxidation of organic matter.
Carbon dioxide is a transparent, odorless and colorless gas. It is
a very important constituent in the atmosphere and a very slight
variation either in its increase or decrease will vitally interfere
with both animal and vegetable life. Green plants in the sunlight
absorb great quantities of carbon dioxide and give off oxygen. The
body obtains its carbon from the food that is taken in while the
oxygen is obtained from the air that is breathed. It is maintained
that one acre of ordinary tree land will withdraw as much as four
and one-half tons of carbon dioxide from the air in one season.
Carbon dioxide is also absorbed by water; hence the oceans and other
large bodies of water perform a very important function in this
respect. In certain localities, such as industrial centers, a very
large amount of carbon dioxide is given off into the air; but this
is quickly taken up and thoroughly mixed with the atmosphere by the
constant motion which is maintained by the varying temperature, air
pressure and other involved factors. It is not allowed to accumulate
in any one place in larger amounts than normal. In this way the
proportion is kept the same at all times.
Hygienists maintain that the regulation of breathing is largely
dependent on the concentration of carbon dioxide in the air cells
of the lungs. This, however, is not true since the process of
respiration is not a question of chemical action nor the influence of
any chemical element in the lungs or in any part of the respiratory
system. The breathing, like all other functions of the body, is under
the direct control of Innate Intelligence within the body.
Innate Intelligence, recognizing the need for more oxygen in the
tissue cells, will bring about an intellectual adaptation by
increasing the respiration. This does not take place, however, until
the need has exceeded the already adaptative possibility when the
reserve amount of oxygen contained in the residual air in the lungs
has been exhausted.
In inspiration the air is taken into the lungs and the oxygen is
taken up by the hemoglobin of the blood as before stated; then the
oxygen is given off to the tissue cells. The hemoglobin absorbs the
carbon dioxide from the tissues and it is then carried back to the
lungs where the process is reversed. That is, the carbon dioxide is
given off and the oxygen is absorbed by the hemoglobin.
The carbon dioxide which is carried to the lungs by the venous blood
escapes into the air cells. The resistance which it meets here
depends upon the percentage of carbon dioxide present in the alveolar
air. Normally the percentage of the carbon dioxide in the alveolar
air is maintained at a pressure of about 5% of an atmosphere. If
the pressure becomes less than this Innate Intelligence will adapt
herself to this condition by decreasing the respiration until the
normal percentage is again attained; or if the pressure goes above
normal Innate will increase the rate of respiration until the amount
of carbon dioxide has been decreased in the alveolar air, for this
poisonous gas must be eliminated. This shows how Innate at all times
is working in an adaptative way to maintain equilibrium in the body.
Ozone (O_{3})
Ozone is not a constant element in air, although of such potency
that a very small amount may be of great importance. In centers of
population it is usually absent. In thickly wooded sections and at
sea it will be found in large quantities, but even here only traces
will be found. It is thought to be formed by the friction of the
sea water against the air in connection with the respiration of
vegetation. It is also formed in nature by electric discharges during
storms.
Ammonia (NH_{3})
Normally there is only a trace of ammonia in air. It is produced by
the decomposition of organic matter. This accounts for the larger
amount being found in the air near the ground. Ground air may contain
ammonia in sufficient quantity to be perceptible to the senses.
Other Constituents
Hydrogen peroxide is a very active oxidizing agent. Rain water and
snow contain very small traces of it. Hydrogen peroxide is not
constant in air, but may be found in very small quantities.
Air also contains small traces of helium, krypton, neon, xenon,
which have no important bearing from a hygienic standpoint. Nitric,
sulphuric and other acids will at times be found in the atmosphere.
These acids are formed principally from industrial processes and
will, therefore, be found near industrial centers, rather than in the
open country or at sea.
AIR PRESSURE
Normal Air Pressure
Ordinary air pressure on the surface of the earth at sea level is,
in round numbers, fifteen pounds to the square inch. It has been
found that the average sized man is exposed to about 34,000 pounds
of pressure. This pressure may be increased or decreased, and if the
change takes place gradually so that Innate Intelligence will have
time to adapt the body to the change, no harm will result. There is a
limit, however, either in a decrease or in an increase of pressure to
which the body may be adapted.
This intellectual adaptation obtains in every tissue cell of the body
as well as in all of its secretions and chemicals so it can be seen
that any sudden change in the atmospheric pressure will disturb the
equilibrium of the entire body.
Reduced Air Pressure
When the atmospheric pressure is decreased it has the same effect on
the individual that the breathing of rarefied or diluted air has. In
this event the adaptation consists in an increased rate of breathing.
It is also asserted that the number of red blood corpuscles is
increased, which in turn increases the capacity of the blood to carry
oxygen. In the diminished air pressure there is a marked decrease in
the amount of oxygen absorption and this accounts for the increase in
the respiration and quickened pulse rate.
As previously stated, if the change from a normal air pressure to a
greatly decreased pressure takes place gradually, thus giving Innate
sufficient time to bring about an adaptation, man will be enabled
to live in a healthy state in a rarefied air. As the altitude is
increased the air pressure is decreased. This is because there is
less air above to exert pressure. Naturally the air near the earth
has the greatest weight above it to exert compression. The air
pressure decreases gradually until, it is assumed, it is gradually
thinned into a perfect vacuum. If oxygen is added to the air it is
possible to maintain life at a remarkably reduced air pressure. A
bird was kept alive by P. Bert in oxygenated air at a pressure of 0.1
of an atmosphere.
The =symptoms= produced in diminished air pressure will vary with
the general conditions of the individual. People suffering from
cardiac disturbances will be affected most by high altitudes. This is
possibly the first symptom to be manifested in rarefied air. If there
is any inclination toward heart weakness it will be observed when the
air pressure is decreased.
The effects of reduced air pressure will vary with circumstances.
There will be increased and deep breathing, with an increase in the
pulse rate. There is likely to be dizziness and ringing in the ears.
The sense of hearing, of sight and possibly of sensations, become
impaired. There may be drowsiness and the patient may have a strong
desire to sleep. The intellectual faculties become dull. Where the
change has taken place very suddenly to the decreased air pressure
there will be syncope, dyspnea, dizziness, nausea and weakness. These
symptoms are commonly known as mountain sickness.
Increased Air Pressure
The greatest air pressure in nature is at sea level. Even the
increased pressure in the deepest mines is so slight that it has
no physiological significance; hence man is exposed to increased
air pressure only under artificial conditions. This subject will be
referred to again under the head of Industrial Hygiene.
Some of the conditions under which man is exposed to increased air
pressure are, for example, divers in diving bells and diving suits,
and caisson workers. At a depth of ten meters of water the air in a
diving bell is compressed to one-half its original bulk, and as a
result the pressure of air is doubled. At thirty meters, or about
100 feet, the pressure is quadrupled, exposing the diver to four
atmospheres or about sixty pounds per square inch.
The danger in increased air pressure is not in going from a normal
pressure to a high pressure, nor does the danger come from the high
pressure. The danger is not from the compression, but rather from
the decompression. The individual must be brought from the increased
air pressure to the normal air pressure very gradually, allowing
Innate sufficient time to adapt the body to the normal pressure of
fifteen pounds to the square inch. If this is done no great amount
of harm will result, although there are some men who are not able to
withstand these changes. This shows a lack of intellectual adaptation
through the body on the part of its Innate. In an experiment P. Bert
exposed dogs to an air pressure of ten atmospheres, or about 150
pounds to the square inch, and then released them very gradually,
producing no ill effects.
When the air pressure is increased it results in an increase in the
absorption of the gases of the atmosphere. There is an increased
amount of oxygen taken up by the blood and the tissues absorb large
amounts of nitrogen. When the pressure is released slowly these gases
gradually escape from the lungs and no bubbles will be formed.
During compression the symptoms are not so severe as those during
and after decompression. During compression the symptoms are a
deepening but slowing of the respiration, a slowing of the pulse
rate, and an interference in evaporation in the water vapor. The
increased pressure on the ear drums will cause pain in the ears and
sometimes the ear drums rupture. There may be an alteration in the
voice, headache and dizziness. However, in a short time, intellectual
adaptation takes place and equilibrium is established by the
internal change and there is at least temporary relief from these
symptoms.
Caisson Dis-ease
The greatest risk to health and life occurs during the time the
individual is coming from the high to normal pressure after the
decompression has entirely taken place. This may produce a condition
known as caisson dis-ease. It may be several hours after the workman
has been taken from the decompressing chambers before the symptoms
appear. Gradual decompression is the only thing that will prevent the
manifestation of these symptoms. When the workman shows any symptoms
of caisson dis-ease he should be rushed back into the compression
chambers and kept there a short time until Innate has a chance to
establish equilibrium in the pressure of the body, and he should then
be taken very gradually through the decompression chambers.
The =symptoms= that appear after decompression are vertigo, nose
bleeding, nausea and vomiting. The most common symptom is the
severe pains in the muscles and joints which is known by the layman
as bends. There may also be temporary or permanent paralysis
called diver’s palsy. In the more severe cases there will be
unconsciousness, and even death.
When the workman is taken too quickly from the high pressure there
is formed gas and air emboli. These may form in the labyrinth of the
ear, in the spinal cord, in the brain, in the heart, or in any other
vital part of the body and not only be distressing but may even prove
fatal.
It must be remembered that the conditions produced by changes in
the air pressure may be classed as traumatic, immunity from which
is not entirely a question of uninterrupted transmission. If
there are subluxations in the spine at the time the workman goes
into the caisson, or if subluxations are produced at the time of
decompression, the interference thus produced will interrupt the
process of intellectual adaptation. Such subluxations should be
adjusted, but it must be remembered that if emboli are formed or if
bends occur the result or the relief is a question of the natural
processes of Innate in the body, and the results will depend entirely
upon the ability of Innate to cope with the traumatic condition.
Innate Intelligence operates through the body according to law, and
it is possible for the body to become so affected and deteriorated
that it becomes a physical impossibility for her then to repair it
and restore it to normal.
We have seen that the normal air pressure at sea level is fifteen
pounds to the square inch. In order that the body will not be crushed
by this weight it is necessary to have an internal resistance to
equal this weight. This internal resistance is maintained in the body
by the tone of all of its parts; it is maintained by the expression
of mental impulses in the tissue cells.
We have also observed that the combining of chemicals is influenced
by the pressure exerted; therefore, in order that the chemical
combinations of the body be constant there must be equilibrium
established between the external pressure and the internal
resistance. This is maintained through the adaptability of the
expression of Innate in the body. As the change takes place
externally there is a corresponding adaptative change taking place
internally and this all requires time. Therefore, in passing the body
from one air pressure to that of another degree, there must be a
sufficient amount of time intervening to allow Innate Intelligence to
bring about the necessary adaptation.
The changes that take place under differing degrees of air pressure
are not purely the result of chemical changes in the body as is
maintained by some, but in all these processes we see the evidence of
intelligent action which we believe is the result of the reasoning
of the intelligence in the body. One evidence of this is that when
the workman is brought gradually from an increased air pressure to
the normal air pressure the gases that have been absorbed by the
tissues under the abnormal condition will be given off through the
normal channels, and less injury will be done. It is interesting to
note that in Nature, man is not exposed to a greater air pressure
than that at sea level; it is only under artificial, man-invented
environments that the body is called upon to withstand a greater
pressure than the normal. It may also be noted that without the
inventions of man it requires quite a little time for man to be
transported from the air pressure at sea level to that of the higher
altitudes as on the mountain tops. This gives Innate Intelligence an
opportunity to bring about an adaptation to this change, since the
change in the pressure takes place so gradually. But with man-made
inventions, such as the automobile and aeroplane, one may transfer
himself from sea level to great heights where the pressure is less in
a very short time. This does not allow sufficient time for adaptation
to take place and is much different from the slow process of climbing
the mountains.
So we see that, after all, most of the necessity for immediate
adaptation of the body to changed environmental conditions is the
result of the work of the educated mind of man, and not the result
of the laws of Nature. In Nature we seldom see the necessity for
sudden or extreme adaptation. But under our present artificial means
of living there are such cases, and these necessitate a study of
the artificial conditions as well as a study of the Innate laws
of adaptation that there may be as far as possible an educated
adaptation to the environment.
HUMIDITY AND TEMPERATURE OF AIR
Humidity
Water vapor is present at all times in the atmosphere. It is the
least constant of all of the air constituents, varying greatly under
different conditions. The temperature produces a greater change in
the amount of aqueous vapor in the air than any other factor. There
may be so much water vapor in the air that the air is spoken of as
being completely saturated. This is known as absolute humidity. If
there is any excess over and above this complete saturation, it
is given off as dew; it is spoken of then as having reached the
dew point. It must be remembered that this absolute humidity does
not represent a constant amount of water vapor, for the amount of
moisture necessary to produce complete saturation varies with the
degree of temperature. It is erroneous to speak of the air holding
water.
“As a matter of fact, the air has nothing to do with it, for it has
always been clearly observed that the presence of water vapor in
any given space is independent of the presence or absence of air in
the same space. The amount of aqueous vapor which a space contains
depends entirely upon the temperature and not upon the presence of
the air.”—Rosenau in _Preventive Medicine and Hygiene_.
The higher the temperature the greater the amount of water vapor in
one cubic foot of air at a temperature of 10° F., while at 100° F.
there would be 19.1 grains at complete saturation. Since increased
temperature increases the amount of aqueous vapor and this aqueous
vapor in turn absorbs heat, we thus see a reciprocal action of the
aqueous vapor upon the temperature.
=Absolute humidity= is all of the water vapor that may be contained
in the air at a given temperature. =Relative humidity= is the
difference between the amount of water vapor that must be contained
in the air at a given temperature to reach absolute saturation and
the amount actually contained in the air at that same temperature.
If the relative humidity of the air in a room becomes as high as
85% the moisture will begin to condense and form on the walls and
objects. This makes the room damp and interferes with the ventilating
and heating of the room.
There is less water vapor contained in the air at high altitudes, the
air being cooler. A large amount of rainfall does not necessarily
produce an increase in the relative humidity. That is to say, a
country with a very high average of rainfall is not necessarily a
damp country so far as the atmosphere is concerned.
Cold Dry Air
Cold dry air is exhilarating and tends to quicken metabolism in
the body, while warm damp air is depressing and tends to retard
metabolism.
The body possesses great possibilities of adaptation to the varying
degrees of temperature and humidity through the action of Innate
Intelligence. With the aid of the educated mind in bringing about
adaptation in the way of clothing, for example, it is possible to
increase the range of temperature and humidity to which the body may
be adapted.
Due to the fact that heat is being constantly formed in the body by
the different processes that are carried on within, it naturally
follows that this heat must be carried out of the body or it will
accumulate and result in harm to the tissues, producing what is
known as heat stroke. This heat dissipation is greatly influenced
by the humidity, or in other words, the amount of water vapor in
the air. The temperature of the air also has some influence on heat
dissipation.
Cold air is made to feel colder by an increase in the amount of
moisture while warm or hot air is made hotter by increasing the
moisture. The reason for this is that the moisture in the cold air
favors heat conduction, hence draws the heat from the body at a more
rapid rate than is normal, while the moisture in the hot air hinders
evaporation.
Innate Intelligence is able, through the specially devised machinery
of the body, to maintain a perfect balance between heat production
and heat dissipation or heat loss. Even though the temperature of
the air may rise, yet if the body is normal it will not produce an
increase in the bodily temperature. Indeed, it is asserted that when
the temperature of the air goes above 70° F. the bodily temperature
would rise if it were not for the perspiration which Innate will
produce through the sweat glands. As long as the perspiration is
produced and is evaporated from the surface of the body the heat
production and heat loss will be kept in perfect balance. But when
something interferes with this adaptative process of Innate and
the individual can not perspire, there will soon be symptoms of
overheating and the temperature of the body will begin to rise.
Evaporation is decreased in an atmosphere in which the humidity is
high. The reason for this is obvious; the atmosphere already filled
with water vapor is slow to take up more. This is because molecules
of vapor given off from the body collide with those in the air and
are returned to the surface of the body as moisture. When this
condition obtains there is an adaptation produced by increasing the
amount of blood to the skin; this increases the temperature of the
surface of the body, but allows for an increase in the heat loss by
radiation, conduction and convection.
The conductivity of the atmosphere for heat is increased by an
increase in the humidity; hence a cool damp air will chill the body
for the reason that the conductivity is increased and bodily heat is
lost more rapidly through conduction. Increased humidity interferes
with the evaporation of perspiration; hence a hot, moist air is
heating to the body and deprives the body of force, making the
patient feel sluggish and fatigued.
There is much moisture given off from the body each day. It is
estimated by Pettenkofer, Voit, Rosenau and others that the average
individual under ordinary circumstances will give off through the
lungs about 290 grams, and from the skin from 500 to 1800 grams
daily. If this fact is kept in mind some idea of the necessity of
proper ventilation will be appreciated.
Warm Moist Air
Workers fatigue much more easily when in warm moist atmosphere. Work
is done much more rapidly in cool dry air and the efficiency of the
worker is noticeably raised; in warm damp air the bodily temperature
rises and the pulse rate increases.
Mental and physical activities are reduced in an atmosphere of
high humidity and increased temperature. This is due mainly to the
reluctance on the part of the individual to put forth an effort
sufficient to perform any great amount of work. There is a general
feeling of languor because of the enervating effect of the air.
There is no serious injury resulting from working in such an
atmosphere, unless there is an increase in the bodily temperature,
and then there may be serious results to the health unless relief
is obtained. When the humidity has reached the point of complete
saturation and the temperature is above 88° F., compensation can no
longer obtain through evaporation and heat stroke may result. The
most noticeable effect of warm moist air under ordinary circumstances
is reluctance to put forth any mental or physical exertion, and a
loss of appetite. With a temperature at 75° F. and the relative
humidity 80%, an individual not accustomed to such will require
complete rest.
It will be noticed that under such conditions Innate Intelligence is
constantly working to bring about intellectual adaptation and that
she is able to do so to a remarkable degree. The glands of the body
are used to produce secretions which constantly bathe the tissues
and keep them cool in the high temperatures, and at a proper degree
of warmth in the low temperatures. The fact that the individual is
indisposed to mental and physical activity in such an atmosphere
is adaptative on the part of Innate. This inactivity is suggested
by means of the languid feeling in order that the body will not be
over-exercised and thus will not increase the amount of heat in the
body; because under these circumstances the process of evaporation
is interfered with and this is one of Innate’s principal means of
regulating the temperature of the body.
Perspiration is an adaptation on the part of Innate, for in this way
the surface of the body is kept moist and as this moisture evaporates
the body is cooled; otherwise the temperature of the body would
increase with every rise in the temperature of the atmosphere. Not
only does this help to regulate the bodily temperature, but it keeps
the surface tissue of the body soft. If there was no perspiration,
the surface of the body would soon become dry, parched and hard. The
skin would become scaly and would crack and become chafed.
Because of these adaptative processes it is possible for the body to
be adjusted to great extremes in temperature. The body may become
accustomed to extremely high temperatures even with high relative
humidity, providing the change takes place gradually and sufficient
time is allowed for the processes of adaptation to take place.
It is very important that the kidneys be able to perform their normal
function in order that these processes of adaptation may take place.
The kidneys are important not only because of the function which they
perform in the excretion of poisons, but because of the function
which they perform in relation to the serous circulation. This is
important because of the secretions that are involved. This subject
will be treated more fully under the subject of Water.
Cold Damp Air
The body quickly becomes chilled in a cold damp air because the
increase in the water vapor increases the conductivity of the air for
heat. It can thus be seen that the heat producing processes of the
body must be increased in order to maintain the normal temperature
of the body. As we know, all activity of the body requires an
expenditure of energy, so if the body is exposed to a cold damp air
for an abnormal length of time it will necessitate an increased
expenditure of internal energy to meet the increased demands for
heat and thus dissipate forces that should and would, under normal
conditions, be utilized in the metabolism of the body. If the heat
production is at a minimum in the body, which it may be, due to
several factors such as old age, infancy, or dis-ease, this exposure
to lowered temperature and high humidity will result in injury to the
body.
An interference with the transmission of mental impulses to the
kidneys resulting in a decrease in their functional activity may
mean a retention of poisons in the body and produce a condition
diagnosed as rheumatism, for example; or an interference with
the serous circulation may result in the tissue cells being
under-nourished. Both of these conditions will interfere with the
processes of intellectual adaptation. Educationally, man may help in
the adaptation by proper clothing and by giving attention to proper
exercise.
Warm Dry Air
By far the most desirable air is the warm, relatively dry air; but as
has already been noted, it is possible to have an atmosphere with a
relative humidity that is too low. If the air is abnormally dry, and
at the same time warm, there will be a great loss of body moisture
due to the increased evaporation. When the loss of water from the
body reaches 21% death ensues. In an experiment performed by Rubner
and Lewaschew it was found that a man weighing about 127 pounds gave
off about 54.1 grams of water in an hour in a temperature of 68° F.
with a relative humidity of 82%; the same individual in a temperature
of 68° F., but with a relative humidity of 82%, gave off only 15.3
grams.
Proper Temperature and Humidity
The most desirable atmospheric conditions are obtained at a
temperature of 68° F. to 70° F., with the relative humidity from 40%
to 60%. This is given only as a general average and will necessarily
vary with many conditions, such as seasons of the year and occupation.
Moderately cool and relatively dry air increases the activities of
the body, makes breathing easy and more frequent, and hence increases
the circulation of the blood. Innate is thus enabled, in such an
atmosphere, to bring about more perfect metabolism.
Proper temperature and humidity of the air in houses, impurities
found therein, source of impurities and their effect upon health,
will all be considered thoroughly under Hygienic Housing.