UNITS /TERMS:
Exchange rate the rate at which outdoor air replaces indoor air. The measurement most commonly heard in the industry is "air changes per hour." This is an indication of the extent to which air moves though a building over time.
BACKGROUND FACTS:
"Sick buildings" are one of the top five threats to human health, as ranked by the U.S. EPA. The EPA has found that indoor air is typically between two and five times more contaminated than outdoor air. In some cases, indoor air can be 100 times more contaminated.
Indoor pollution sources that release gases or particles into the air are the primary cause of poor indoor air quality. Inadequate ventilation can increase indoor pollutant levels by: a) not bringing in enough outdoor air to dilute emissions from indoor sources, and b) not carrying indoor air pollutants outdoors. Low exchange rates typically increase pollutant levels.
High temperatures and humidity can increase concentrations of some pollutants.
Combustion sources are common indoor air pollutants and include oil, gas, kerosene, coal, wood, and tobacco. Homeowners can reduce the likelihood of combustion gasses entering indoor air space by installing sealed-combustion furnaces and power-vented water heaters.
Other sources of pollutants are building materials and furnishings (offgassing), asbestos-containing insulation, wet or damp carpet, pressed wood products, household cleaning and maintenance products, air fresheners, central heating and cooling systems, humidification devices, and outdoor sources such as radon, pesticides, and outdoor air pollution. Choosing building materials wisely, such as low volatile organic compound (VOC) paints, carpets, cabinets, and substitute wood products can improve the indoor air quality in a home or building by reducing the concentrations of these pollutants.
Health effects from indoor air pollution may be experienced soon after exposure (irritation of the eyes, nose or throat, headaches, dizziness, and fatigue) or, possibly, years later (respiratory disease, heart disease, and cancer). Health effects of poor indoor air quality often appear as allergy or asthma symptoms.
Consumers may be concerned that "tightening" a house (through energy-efficient windows, weatherization, etc.) will inevitably lead to poor indoor air quality. This is a common misconception. Well-designed ventilation inside a well-sealed house can actually help control moisture and pollutants, save energy, and provide a comfortable indoor environment. If you are concerned, take advantage of the additional information below and test indoor air quality. "Tight" buildings can be very beneficial to owners and occupants when built properly and ventilated correctly.
U.S. Environmental Protection Agency: Basic Information About Indoor Air Quality (IAQ)
U.S. Environmental Protection Agency: Sources of Indoor Air Pollution - Improving Indoor Air Quality
U.S. Environmental Protection Agency: Indoor Air Quality in Large Buildings
TESTING:
You may be interested in testing for molds, allergens, bacteria, aldehydes, VOCs, pesticides, and other pollutants. Testing options range from self-test kits to full evaluations by IAQ professionals.
IAQ professionals are trained in observing homes or buildings, talking to affected persons, identifying potential issues, evaluating ventilation performance, conducting sampling and analysis, and ultimately resolving IAQ problems.
IMPROVING INDOOR AIR QUALITY:
Indoor air quality problems can be addressed and improved in most cases. The most effective way to improve indoor air quality is typically to remove the source of the air pollution, but it is not always practical to do so.
Ventilation improvement, (increasing the amount of outdoor air that enters the building and the amount of indoor air that leaves the building) is another effective way of lowering indoor air pollutant concentrations. The simplest way to improve poor indoor air quality is to provide better ventilation with adequate air changes per hour. Opening windows, operating attic and window fans, running window air conditioners with vent controls open, and running bathroom and kitchen fans are all options for increasing outdoor air ventilation rate.
Air cleaners are another option for improving indoor air quality. Generally, air cleaners are very effective at removing particles from the air. However, air cleaners are typically not designed to remove gaseous pollutants. |
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Evaluation of Low-VOC Latex Paints: U.S. Environmental Protection Agency: Inside IAQ
The Inside Story: A Guide to Indoor Air Quality
