Brian Cornwall, age 15, of Orlando, Fla., for his question:
WHY IS VENTILATION OF A ROOM IMPORTANT?
Ventilation supplies fresh air to rooms and removes stale air. Ventilation is important because it can make people feel more comfortable, and it can also remove harmful materials from the air.
In places such as mines or tunnels, poisonous gases may be present which must be removed through ventilation before men can safely work there. Also, factories often use ventilation to remove harmful fumes that may result from industrial processes.
For people to feel comfortable, they need fresh air that is free from dust, soot and odors. The air must not be too warm or too cool and it must have the right amount of moisture.
Even if the air in a room is fresh to start with, changes take place when people come into the room. The air becomes warmer because the human body gives off heat. The amount of moisture in the air increases because of the water vapor given off as people breathe and perspire. Also, the air becomes stale because of perspiration and the oily matter given off from people's skins, noses, throats and clothing.
The more people there are in a room, or the harder they work, the faster the air becomes stale. Stale air must be removed and replaced with fresh air. If the air outside is fresh, simply opening a window and perhaps turning on a fan will ventilate the room.
But if the outside air is not fresh or the room is on the outside of a building, special equipment is needed to clean the air, cool or heat it and remove or add moisture. This equipment is called air conditioning.
The amount of air required for proper ventilation varies, depending on the room and the number of people in it. Under normal conditions, from 10 to 30 cubic feet of fresh air must be supplied each minute for each person in the room.
The correct temperature of a room depends on the age of the people in it.
For schoolchildren, the ideal temperature of a room should be about 70 degrees Fahrenheit. For older persons, it should be about 75 degrees Fahrenheit. And for elderly persons, a room's temperature should be kept at about 80 degrees Fahrenheit.
If the temperature of a room is comfortable, the amount of moisture in the air usually does not affect people. But if it rises above about 75 degrees Fahrenheit, too much humidity or moisture causes discomfort.
People remove the gas oxygen from the air they inhale and give off another gas, called carbon dioxide, to the air they exhale. Many persons once thought that the carbon dioxide gas breathed out was harmful to anyone who breathed it in again. Although breathing increases the carbon dioxide and decreases the oxygen in a room, these changes are so slight that they have little or no effect on a person's health.
The electric fan is an ideal device to help solve ventilation problems. Exhaust fans are useful to draw cooking odors and gases out of kitchens. Room fans can be used to push air away and create an air current.
The most common electric fan is the one used in homes to create a breeze in hot weather. Ventilation is often made easy by the movement of fresh air.