No element in nature is more important than air. A person may live two to four weeks without food, three to four days without water, but cannot live more than more than a few minutes without air. With the progress of civilization higher living standards have been established and many improvement have been made. The general health of people has been protect by sanitary regulations, hence the longer people are living, (many years more than their ancestors.) We are now entering a time of world-wide interest in the quality of the air we breathe in the open atmosphere and in the rooms we live and work. The EPA was created to guard the atmosphere of the USA and help other nations to become more quality conscious of their own environment.

The effects of temperature on the body are well known by all. When rooms are too hot or too cold that fact is sensed immediately, but the effects of humidity are not as well known. Each year many people are overcome with heat exhaustion or heat stroke simply because they do not recognize the effects on the body by high levels of humidity. These effects are felt wherever people may be, the home, the work place, any where people congregate for business or for pleasure. Too much humidity lessens the ability of the body to give off excess heat. If humidity is too low the air absorbs too much moisture from the body.

Today the control of humidity, circulation, ventilation, temperature and air cleaning are all considered a part of air conditioning. The outdoor weather cannot be controlled. However with in a confined space a desired climate can be created by the control of the air and its properties. All people live in shelters of one kind of another. The civilized world spends most of their time working and relaxing inside of buildings. Because of this, air conditioning has a definite part in the general well-being of the people of the world.

Not only is temperature and humidity maintained, but fresh air is introduced, odors removed, and atmospheric conditions inside each room of a building can be uniform or different depending on the needs of the occupants.

People consume about six pounds of food a day. The average person breathes about 30 pounds of air a day. This shows that by weight the human body requires five times as much air as food. This gives an idea of the importance of the quality of the air we breathe.