Clearing The Air

Seven do's and seven don't for improving indoor air quality

One of the articles in Designing A Sustainable Future (IC#35)
Originally published in Spring 1993 on page 21
Copyright (c)1993, 1996 by Context Institute

Building a healthy house is no more difficult than building an unhealthy one. However, it takes more than just selecting non-toxic materials; builders of healthy homes need to have an understanding of how a house functions – for example, how a house "breathes."

John Bower, author of Healthy House Building and other books on indoor air quality, suggests these guidelines for designing and constructing a healthy home. For more information check the Resources Guide on page 58.


1. Do build in a clean location * Selecting a site away from sources of air pollution is the first consideration in healthy house construction.

2. Do build an airtight structure * This not only improves energy efficiency, but, when coupled with a mechanical ventilation system, it gives the occupants maximum control over the indoor air. An airtight structure also minimizes occupant exposure to insulating materials.

3. Do install a ventilation system * Mechanical ventilation can supply fresh air as needed. Relying on infiltration for an air supply is unreliable and frequently insufficient.

4. Do install a radon removal system * It is difficult to predict if a particular house will have a radon problem, but it’s easier to take precautions during construction than to mitigate radon in a completed house.

5. Do use metal or solid wood cabinetry * Kitchen and bathroom cabinets are generally made of manufactured wood products that contain glues and use finishes high in formaldehyde. Use solid wood cabinetry with a low-tox finish or metal cabinetry with a baked-on finish.

6. Do use water-based adhesives, caulks, paints, etc. * Water-based products are more benign than solvent-based products because they have lower levels of volatile organic compounds (VOCs). Nonetheless, water-based products aren’t perfect, as they contain other ingredients that can cause negative health effects. Several specialty manufacturers now offer more benign alternatives.

7. Do test materials with sensitive occupants * This is necessary when a home is to be occupied by someone with chemical sensitivities because different people have varying reactions to the same material. Testing should be done under the supervision of a physician.


1. Don’t use carpeting * When it comes to poor indoor air quality, carpeting is one of the worst offenders. New synthetic carpeting outgasses more than 100 different VOCs. Old carpeting is a haven for microbes, some of which are highly allergenic. A conventional portable vacuum cleaner blows a great deal of dust into the air. Shampooing is not totally effective, and it may contribute to an increase in microbes.

2. Don’t use products high in formaldehyde * Of the two primary types of resins used in manufactured wood products – U-F (urea-formaldehyde) resins are perhaps 10 times more potent than P-F (phenol-formaldehyde) resins. P-F resins are used in all construction grade products (interior and exterior plywood; oriented strand board; laminated beams; fiberglass insulation; etc.). U-F resins are used in hardwood plywood for wall paneling and cabinetry, medium-density fiberboard for shelving, and particle board.

No products containing U-F resins should be used within occupied spaces. P-F resins can be used in the structure, but with sensitive occupants, they should be well separated from the living space.

3. Don’t asphyxiate the occupants * If a conventionally aspirated combustion appliance is used, make sure that backdrafting and spillage will not occur. Sealed combustion, solar heating, electric or heat-pump furnaces and water heaters are highly recommended alternatives. Gas ranges are probably not a good idea. Even if backdrafting and spillage are not serious enough to kill the occupants, they can result in enough low-level carbon monoxide to result in flu-like symptoms.

4. Don’t create a depressurized house * Depressurization can result not only in backdrafting and spillage, but also infiltration of pesticides, mold spores, particles of insulation, radon, and other soil gases. Depressurization occurs because of the HVAC system’s blower, powerful natural drafts in chimneys, clothes dryers, central vacuums, etc. Occupants should open a window slightly when using such exhaust equipment.

5. Don’t ignore physics * Moisture migration, wind, mechanically induced depressurization, and outgassing, all follow well-defined physical laws. If those laws are properly understood, healthy, durable houses can be built.

6. Don’t believe everything you hear * There is an increasing amount of information available on healthy construction; some is better than others. When dealing with sensitive individuals, don’t believe anyone who tells you that a product is universally tolerable.

7. Don’t panic * If you’re apprehensive about healthy construction, relax. There are many books and periodicals dealing with the subject.