Pollutants In The Home, Part IV (The Holy Grail)

Moisture control is the Holy Grail of Indoor Air Quality.

Water in the home can come from many sources: leaking or by seeping through basement floors, from showers, and even from cooking.

The amount of moisture that air can home depends on the temperature of the air. This is true whether we are talking about air inside the house or outside.

As temperature decreases, air is able to hold less moisture. We see this during our Michigan winters as moisture condenses on cold surfaces. This moisture can encourage biological pollutants to grow.

There are many ways to control moisture in our homes:

• Fix leaks and seepage. If water is entering the house from the outside, our options range from simple landscaping to extensive excavation and waterproofing. (The ground should slope away from the house.) Water in the basement can result from the lack of gutters or a water flow toward the house. Water leaks in pipes and around tubs and sinks can provide a place for biological pollutants to grow.
• Put a plastic cover over dirt crawlspaces to prevent moisture from coming in from the ground. Be sure crawlspaces are well-ventilated.
• Use exhaust fans in bathrooms and kitchens to remove moisture to the outside (not into the attic). Vent the  clothes dryer to the outside.
• Turn off certain appliances (such as humidifiers and kerosene heaters) if moisture develops on windows or other surfaces.
• Use dehumidifiers and air conditioners, especially in hot, humid climates, to reduce moisture in the air, but be sure that the appliances themselves don't become sources of biological pollutants.
• Raise the temperature of cold surfaces where moisture condenses. Use insulation and storm windows. (A storm window installed on the inside works better than one installed on the outside) Open doors between rooms (especially doors to closets which may be colder than the rooms) to increase circulation. Circulation carries heat to the cold surfaces Increase air circulation by using fans and by moving furniture from wall corners to promote air and heat circulation. Be sure that your house has a source of fresh air and can expel excessive moisture from the home.
• Pay special attention to carpet on concrete floors. Carpet can absorb moisture and serve as a place for biological pollutants to grow. Use area rugs, which can be taken up and washed often. In certain climates, if carpet is to be installed over a concrete floor, it maybe necessary to use a vapor barrier (plastic sheeting) over the concrete and cover that with sub-flooring (insulation covered with plywood) to prevent a moisture problem.
• Moisture problems and their solutions differ from one climate to another. Here in Michigan, it is cold and wet. The Southwest is hot and dry, the South is hot and wet, and the Western Mountain states are cold and dry. All of these regions can have moisture problems. For example, evaporative coolers used in the Southwest can encourage the growth of biological pollutants. In other hot regions, the use of air conditioners which cool the air too quickly may not be left running long enough to remove excess moisture from the air. The types of construction and weather for the different climates can lead to different problems and solutions.