The Harvester World: Volume 9, number 11, November 1918

              Ventilation

By Dr. A. J. Devaney, Works Physician, Akron, Ohio

Winter with its closed windows and artificial heat, with its increasing influence on sedentary tendencies, is upon us. We don't get out so much in the winter time, and when we do, we don't enjoy the freedom of action as in milder seasons. We keep our windows closed to conserve coal and prevent drafts. But the importance of pure air is all the more greatly to be emphasized. We should regulate our home and office temperatures at the expense neither of our coal pile nor our health. Pure air should not have to fight microbes for its very existence all winter long. Let proper ventilation do it. If you would be much more nearly immune to colds, "Flu", and other related afflictions, feed your respiratory system on pure air.— The Editor.

VENTILATION is a process of changing the air of rooms or other enclosed places so that a certain standard of purity may be preserved to offset the vitiation by the breath of the in¬ habitants, combustion, illuminating gas and other causes.
Of all the various impurities that are found in the air of inhabited rooms, the percentage of CO, (carbon dioxide gas) from the exhaled breath, forms the most easy index for determining the com|ileteness of ventila¬ tion. The open air of cities contains between 3.5 and 4 ])arts by volume of this gas in 10,000 parts of air. There is little, if any, difference between the air of good residence districts in cities and that in the country.
It is admitted by authorities on this subject that the air ill which people work and sleep should not contain more carbonic gas than 10 in 10,000 parts. Some authorities claim it should not contain more than 8 iu 10,000 parts. The rate at which a person expires COj varies widely, being least in sleep, greater in waking rest, and much greater iu violent exercises. Gas light adds to the vitiation of the air in rooms. Roughly speaking, one lighted gas jet is equivalent to one adult male.
As a basis on which to calculate proper ventilation, authorities estimate the production of COj per adult as .6 cubic ft. per hour. Hence he will produce per hour, in 6,0(X) cu. ft. of air, a pollution amounting to one part COj in 1,000 cu. ft. of air. Therefore, to preserve the lowest standard of purity allowed by sanitarians, venti¬ lation must go on at the rate per person of 1,000 cu. ft. of air per hour.
In order that a room may be ventilated properly three things are necessary: First, an inlet or inlets for the air. Second, an outlet or outlets for the air. Third, motive power to produce and maintain the current.
Ventilation systems are spoken of as natural and arti¬ ficial. In natural ventilation no motor force is made use of. The wind, the elevated temperature of the room, the draft from open fire places, etc., are utilized. This was the first means used, and when proper attention is given to the placing of inlets and outlets it suffices for small buildings.
Mechanical ventilation is usu¬ ally effected by forcing into the building air which has been washed by being passed through a column of water and then heated  to a definite tempera- Our ancestors
tvire.   This method of ventila- venti
tion is independent of the outer temperature and wind. It supplies an even temperature of air and the air is washed free from any impurities it might contain. Another method is the vacuum system. By this system the motor force is applied at the outlet and the air is drawn from the room.
It is a time honored saying that "Fresh air is free", but a little examination into the ventilation, or lack of it, in many of our office buildings and apartment houses, will show how poorly we take advantage of it. In many, if not most of them, the question of ventila¬ tion is simply left to take care of itself.
Our ancestors in the dim and dark ages of the past when they first built huts, built them so loosely they did not need ventilation. A little later, however, they closed up the crevices with clay and knocked a hole in the side wall to admit air and light, and this seems to be as far as some fiave got 3'et; a hole in the wall to admit air. Natural ventilation sufficed for our forefathers because their homes were comparatively small and had open fire jilaces which helped to create a draft. But it is absurd to think a few open windows will suffice to ventilate a large flat building. Further, our forefathers were not so susceptible to the incon¬ venience of a draft as some of our more modern hot¬ house products.
The advantage of simple and systematic ventilation is not to be measured only by the proportion of CO,. Another criterion by which to gauge pure air is the amount of oxidisable organic matter it contains. Still another, and a most valuable one, is the number of micro-organisms (bacteria) present—some of them disease producing. In outside air the number is low. Ill poorly ventilated rooms the number is 600 times as great.
The human organism needs a continuous supply of pure, fresh air to keep in   good  health.     Absence of this means deterioration, susceptibility to disease.    In short, inefficiency.    The  bad effects  of  stagnant  air are accumulative.   They grad¬ ually undermine the health.  A poorly ventilated  room  is a  nursery of disease germs which   an  occasional  flush¬ ing with fresh  air  will   not remove.
The best and most modern ventilation for office buildings and apartment houses is a con¬ stant supply of washed fresh air at a reasonable tempera- did not need ture, forced in by mechanical lation means,