Air Quality and the Home Inspector

More recently, air quality in residences has become a heightened concern to homeowners. Studies show indoor air quality often to be directly linked to health problems and there is now more demand for proper testing. However, health effects from pollutants vary with individual sensitivity, which complicates matters. Some reactions occur after a single exposure, others only after repeated exposure. Some are immediate while others may take years to become apparent.

Air quality testing is not customarily included in home inspections governed by the Washington State Standards of Practice, nor will it automatically be a part of the inspection report. In fact, many home inspection contracts specifically exclude investigation into air quality or the presence of environmental hazards such as radon gas or urea formaldehyde. Nevertheless, some home inspectors offer such services for extra fees, and in any case there is an overlap in terms of the approach to finding potential residential problems. This article shows how to form your own home inspection checklist for examining possible pollutant sources, adequacy of ventilation, ways to assess air quality, and ways to improve air quality.

Several kinds of pollutant sources affect indoor air quality. One kind includes byproducts of the combustion of oil, gas, kerosene, coal, wood, or tobacco. Another comes from building materials or furnishings, such as insulation containing asbestos or cabinets and furniture made from pressed wood. A third kind affecting the quality of indoor air results from products used for household cleaning, maintenance, personal care, or hobbies. There may be side effects from the central heating and air conditioning system or from humidification devices. And air pollution, pesticides, radon, or other pollutants occurring outdoors might result in degraded air quality inside. All of these pollutant sources may be intermittent or continuous.

Ventilation, or the replacement of indoor air with outdoor air, plays an important role in determining indoor air quality. Usually, the higher the air exchange rate, the better the air quality. Infiltration, in which outdoor air works its way in through cracks or joints in walls and floors, is one kind of ventilation. Houses designed to save energy may severely limit infiltration and consequently might have lower air quality than so-called "leaky" houses. Besides infiltration ventilation occurs naturally by means of open windows and doors and mechanically through bathroom and kitchen fans or air-handling systems.

There are various ways to assess air quality. One (indirect) possibility is a professional pest inspection, since poor (especially damp) air quality often causes rot, mildew, mold, or infestation. Another is hiring someone to measure the level of specific pollutants. In the case of radon, this should be relatively inexpensive, but to measure a broad spectrum of pollutants is likely not worth the inspection cost unless absolutely necessary. An informal way to assess air quality is to acclimate to the outdoors and then, upon re-entering, to note if you detect odors. Also, look for condensation on windows or walls, smelly or stuffy air, and areas where items become moldy. Try these informal tests if you've recently weatherized your house, because weatherization reduces infiltration, possibly degrading air quality with increased pollutant concentration.

If you determine it's necessary to improve indoor air quality, there are three options: source control, better ventilation, and/or air cleaners. Depending on the particular pollutant source(s), controlling it (them) may be simple or complicated, inexpensive or costly. For instance, it is one thing to stop burning tobacco or using certain household products and quite another to replace insulation or to clean up the quality of outdoor air pollution. The second approach towards improved air quality may be more practical, especially if your climate is conducive to using natural ventilation. Air cleaner effectiveness at improving air quality depends on the nature of the pollutant(s) to be removed, the amount of pollutant collection/filtration, and the degree of air circulation. They are designed to remove particle-based pollutants, not gaseous ones, and are ineffective against radon.

For more related information, see www.HomeInspectionWA.net.