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What practices ensure healthy indoor environmental quality?

Photo of the interior of the Lake Tahoe Basin management Unit Visitor's Center.

The Lake Tahoe Basin
Management Unit Visitor's Center
and Supervisor's Office
experiences low humidity for
most of the year.

Forest: Lake Tahoe Basin MU
Region: 5, 4

Four main factors contribute to a healthy indoor environment.

Fresh Air—We all need fresh air, even when we're inside a building. Even if there are no sources of indoor air pollution, the carbon dioxide we exhale needs to be exhausted outside the building and fresh oxygen brought in. Ventilation rates should be at least as high as those defined in ASHRAE Standard 62.1—Ventilation for Acceptable Indoor Air Quality or Standard 62.2—Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. Ventilation rate standards vary depending on the use of the space. For example, 15 cubic feet per minute per person is the minimum for residences and 20 cubic feet per minute per person is the minimum for meeting spaces. Ventilation can occur mechanically through your furnace or by using a fan, naturally by opening a window, or by infiltration. Older buildings were pretty drafty, so lots of air naturally infiltrated and flowed through them. Newer buildings are constructed much more tightly, so mechanical or natural ventilation must be supplied for recommended ventilation rates to be achieved. Be sure your building is well ventilated using energy-efficient methods.

Building Products and Systems—Unfortunately, buildings often contribute to their own indoor air quality problems. Some building products, particularly paints, carpeting, and building panels, emit volatile organic compounds. Older buildings may contain asbestos, which can be released into the air when asbestos-containing materials are disturbed. Bacteria may grow in heating or air conditioning systems and cause Legionnaire's disease or other health problems. A poorly maintained wood burning or natural gas furnace or stove may produce carbon monoxide. When there is a practical choice, select sustainable products and systems that are less likely to contribute to indoor air problems and consider installing air-handling equipment with filters to remove pollutants from the air. Make sure all your equipment is serviced and cleaned regularly. See the Facilities Toolbox section on Hazmat in Buildings for more information on some common issues.

Cleaning and Pest Control—Cleaning and pest control products can be bad for the people who use them or are around them. Fortunately, low-toxicity cleaning supplies are becoming more common and less expensive. Information on environmentally preferable cleaning products is available through the U.S. Environmental Protection Agency.

It can be a challenge to control pests without using toxic products that also may affect people. Some pest control companies now specialize in nontoxic pest control. Less toxic pest control products such as EcoCote, citrus and other repellents, diatomaceous earth, and traps are available for control of many pests. When nontoxic alternatives are available and effective, they should be used. Unfortunately, there is no database of nontoxic pest control methods. However, check out Controlling Rodents in Forest Service Facilities: Reports from the Field (Optional link for FSweb users), Preservative-Treated Wood and Alternative Products in the Forest Service (Optional link for FSweb users), and Quit Eating My Signs! Pepper-Based Coating Discourages Animals from Damaging Structures (Optional link for FSweb users) for information on control of chewing insects and animals.

Appropriate Humidity—Parts of the United States have very low humidity. In these areas, humidifiers are often used to raise indoor humidity to a comfortable level. Most of the country is normally humid. In humid areas, it is important to limit interior humidity, which can damage the structure and lead to the growth of mold. Showers, cooking, and even people exhaling water vapor add humidity to indoor air. It's important to get that excess moisture out of buildings using fans, dehumidifiers, or other means. Refrigerating air conditioners dry as well as cool the air. In many areas of the country, the drying is as important to human comfort and building durability as is the lower temperature. Excessive moisture sometimes gets into buildings through leaks in siding, roofing, and foundations. This moisture often hides inside the building structure and leads to decay. Check out the section on rot resistance in the building quality and durability section of this toolbox for more information about preventing mold.

Other indoor air quality issues include radon, other soil gases, and pollutants or airborne particles that are sucked into a building through the ventilation system, windows, or doors. The U.S. Environmental Protection Agency maintains a good Web site on indoor air quality that provides more information and practical recommendations for dealing with indoor air quality problems.