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Indoor Air Quality

FACT: Air pollution is a serious problem—especially inside your home!

The EPA has named indoor air pollution as one of the top 5 environmental risks to public health. The EPA also reports that indoor air can be up to 100 times more polluted than the air outside. 100 times!

Indoor Air Quality: (IAQ) deals with the content of interior air that could affect health and comfort of building occupants. The IAQ may be compromised by microbial contaminants (mold, bacteria), chemicals (such as carbon monoxide, radon), allergens, or any mass or energy stressor that can induce health effects. Recent findings have demonstrated that indoor air is often more polluted than outdoor air (albeit with different pollutants) although this has not changed the common understanding of air pollution. In fact, indoor air is often a greater health hazard than the corresponding outdoor setting. Using ventilation to dilute contaminants, filtration, and source control are the primary methods for improving indoor air quality in most buildings. Click here for more information from the American Lung Association.


One way of quantitatively ensuring the health of indoor air is by the frequency of effective turnover of interior air by replacement with outside air.

The use of air filters can trap some of the air pollutants. The Department of Energy’s Energy Efficiency and Renewable Energy section wrote “[Air] Filtration should have a Minimum Efficiency Reporting Value (MERV) of 13 as determined by ASHRAE 52.2-1999.” Air filters are used to reduce the amount of dust that reaches the wet coils. Dust can serve as food to grow molds on the wet coils and ducts and can reduce the efficiency of the coils.

Moisture management and humidity control requires operating HVAC systems as designed. Moisture management and humidity control may conflict with efforts to try to optimize the operation to conserve energy. For example, Moisture management and humidity control requires systems to be set to supply Make Up Air at lower temperatures (design levels), instead of the higher temperatures sometimes used to conserve energy in cooling-dominated climate conditions. However, for most of the US and many parts of Europe and Japan, during the majority of hours of the year, outdoor air temperatures are cool enough that the air does not need further cooling to provide thermal comfort indoors. However, high humidity outdoors creates the need for careful attention to humidity levels indoors. High humidities give rise to mold growth and moisture indoors is associated with a higher prevalence of occupant respiratory problems.

According to the National Safety Council, Americans spend about 90 percent of their time indoors, and 65 percent of that time at home. Thus poor indoor air quality can have a significant impact on people’s lives, especially those who are most vulnerable: infants and children, pregnant women, the elderly, and those who have chronic illnesses.

Steps can be taken to help improve indoor air quality at home, the workplace, and in other indoor environments. Some of those steps include the following:

  • istock_000005139780xsmall.gifInstall an air purifier, or an air purification system. Caution is advised. Ozone-based air cleaners are not advised and both the U.S. EPA and the California Air Resources Board have issued advisories on the use of ozone air cleaners. California is currently proposing to regulate ozone air cleaners.
  • Change filters on central cooling and heating systems and air cleaners according to the manufacturer’s directions.
  • Ensure good ventilation.
  • Have any air-conditioning systems inspected regularly to verify that there is no internal contamination build up contributing to poor indoor air quality.