PATH - A Public Private Partnership for Advancing Housing Technology

Clearing the Air

It happens to everyone. You get a little distracted, overcook dinner, and then every person who enters the house all evening asks, "What's burning?!" This illustrates how contaminants can linger inside your home. But many contaminants are odorless and go undetected by the human nose. In addition, humans readily assimilate most smells anyway, so your nose isn't a very reliable indicator of poor indoor air quality.

Keeping the Air Clean

Good ventilation is a prerequisite for healthy indoor air. Without proper ventilation everyday activities like cooking (especially with gas); showering; and even breathing often make your indoor air more polluted than the air outdoors. New carpeting and fresh paint can make it worse. Your house will always require a certain ventilation rate, but you can minimize the need for ventilation by controlling and reducing the contaminant generated within your home, and by installing some sort of an air treatment system.


ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommends a minimum ventilation rate of 0.35 air changes/hour, which means that 35% of the air in your home should be replaced by outside air every hour. In most older homes this is accomplished by the normal leakage through cracks, spaces and penetrations in outside walls and around doors and windows. Newer homes are built "tighter" for energy efficiency, and some type of mechanical ventilation must usually be incorporated into the HVAC (heating, ventilating and air conditioning) system to achieve this ventilation rate.

Minimizing Indoor Pollution

Several common products and practices reduce the quality of your indoor air. Here are several, including some identified by Leeann Sagula of BBEI in the Sept./Oct. 2004 issue of eco-structure magazine.

Make sure your ducts are clean. Clean ducts will help control the air quality in your home. Go to the National Air Duct Cleaners Association to find a certified duct cleaner. Read the EPA's " Should You Have the Air Ducts in your Home Cleaned," especially to find out whether you should allow chemical biocides to be used during this process.

Air Treatment and Purification

Your HVAC inlet should always be properly filtered. A good filter will minimize the dust, pollen and other contaminants that are introduced into your home. Normal filters remove only dust and some pollens. HEPA filters do a much better job, and some are equipped with media that also filter selected chemicals.

Dehumidifiers are great for controlling humidity in closed spaces, and if you control humidity you are one step toward controlling mold. A ventilation control system can be installed to control the ventilation and to maximize the home's overall HVAC efficiency. More elaborate central air purification/ventilation/dehumidification systems can do it all, but of course they cost more.

Read more about indoor mold and mold control in EPA's " A Brief Guide to Mold, Moisture and Your Home" and in the NAHB Research Center's " Mold in Residential Buildings."

Content updated on 2/27/2007

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