Indoor Air & Mold

Environmental Protection Agency (EPA) studies of human exposure to air pollutants indicate that indoor levels of pollutants may be 2-5 times, and occasionally more than 100 times, higher than outdoor levels. These levels of indoor air pollutants may be of particular concern because most people spend about 90% of their time indoors.

Indoor air pollution sources come from a vast variety of sources inside any home. Some potential sources of indoor air pollution include:
  • Asbestos
  • Biological contaminants (mold, mildew, pet dander, house dust, etc.)
  • Building materials and furniture with pressed wood products
  • Combustion sources (oil, gas, kerosene, coal, and wood)
  • Lead
  • Pesticides
  • Products for household cleaning and maintenance
  • Radon
  • Tobacco products
Multiple Factors
While pollutant levels from any individual source may not pose a significant health risk by itself, most homes have more than 1 source that when combined has the potential to contribute to indoor air pollution. The relative importance of any single source depends on how much of a given pollutant it emits and how hazardous those emissions are. In some cases, factors such as how old the source is and whether it is properly maintained are significant. For example, an improperly adjusted gas stove can emit significantly more carbon monoxide than one that is properly adjusted.

Intermittent Pollutant Release
Some sources, such as building materials, furnishings, and household products like air fresheners, release pollutants more or less continuously. Other sources, related to activities carried out in the home, release pollutants intermittently. These include:
  • Smoking
  • The use of an improperly vented or malfunctioning stoves, furnaces, or space heaters
  • The use of cleaning products and pesticides in house-keeping
  • The use of paint strippers in redecorating activities
  • The use of solvents in cleaning and hobby activities
High pollutant concentrations can remain in the air for long periods of time after some of these activities are complete.

Other Issues
Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air pollutants out of the home. High temperature and humidity levels can also increase concentrations of some pollutants. Fortunately, there are steps that most people can take both to reduce the risk from existing sources and to prevent new problems from occurring.