Ventilation

VENTILATION By ventilation is meant the process of chang ing or renewing the air in a building in order that the supply may remain as pure as possible and be in such a state as to be healthful for breathing purposes. This is a subject which, unfortunately, until recent years, has com manded too little attention from all parties who should be vitally interested; and the acquisition of a perfect system of ventilation has been generally regarded as a luxury rather than the necessity it has proven to be. Ventilation is of even greater importance than heating, and we are fast coming to realize this, making provision for it as we recognize its worth. No architect solicitous of his standing would to-day plan a theater, church, public hall, school, or similar building which is intended to be occupied by a large number of people at the same time, with out making adequate provision for the removal of the foul air within and the substitution of pure air from without for breathing purposes. And yet, of the thousands of dwellings erected each year throughout the country, we are war ranted in stating that not even so large a proportion as one in one hundred has any special method applied for ventilating purposes.

The time is coming, and that not far distant, when no dwelling of any size, of the least im portance, will be constructed without provision being included whereby the occupant may periodically remove the foul air and admit a pure supply.

How Air is Contaminated. In order prop erly to understand how the air we breathe is contaminated or rendered foul and unfit for breathing, it is necessary to know the composi tion of air.

The earth is completely surrounded by an envelope of air or atmosphere several miles thick. This gaseous covering forms, as it were, a vast ocean, at the bottom of which we live and move. The substance of the air is a mixture consisting principally of oxygen and nitrogen, in the proportion of about one part (by volume) of the former to four parts of the latter, with a very small proportion (about three or four parts in ten thousand) of carbonic acid gas. Carbonic acid gas results from all combustion— being produced in considerable quantities even by that form of combustion which takes place in animal respiration. Oxygen is the life-giving

quality in the atmosphere, without which all living things would die. The oxygen in the air within a room is consumed by the burning of illuminants—such as candles, coal oil in lamps, and gas—and also as a result of the process of breathing.

In addition to the above substances, there is also present in the atmosphere more or less aqueous vapor or moisture, the amount varying with the condition of the weather or the proximity of the air to a body of water. We use the term humidity to express this ingredient, and the term relative humidity to indicate the relation existing between the moisture actually present in the air and that which would be present were the air completely saturated.

Carbonic acid gas is not in itself always harmful, as its presence in soda water and other carbonated drinks will attest. However, when breathed into the lungs in the process of respira tion, and when the oxygen breathed with it is consumed, the exhalations from the lungs con tain poisonous matter, and the continued breathing of many people confined within a room will in time so vitiate the atmosphere as to render it dangerously baneful.

Air is vitiated or contaminated, then, by the burning of illuminants, as before noted, and by the exhalations of the people inhabiting the room or building. It may also be tainted by fumes and odors from certain chemicals, etc.

The amount of carbonic acid gas in the air we breathe should never exceed six or seven parts in 10,000. When present in greater pro portion—say, ten or twelve parts in 10,000— there will be a feeling of closeness or stuffiness experienced by the occupants of the room, fre quently causing fainting spells, headaches, etc. An eminent physician recently stated that the breathing of a plenteous supply of pure fresh air constitutes the best medicine to cure the ills of mankind—notably so, the dread one of tubercu losis (consumption) and allied maladies. Aside from its curative powers, pure air is also an efficient preventative of sickness.