There's plenty of concern, with good reason, about air pollution. But many people are unaware that indoor pollution can be just as bad as, or even worse than, the outdoor kind.

Studies of human exposure to air pollutants by the Environmental Protection Agency indicate that indoor air levels of many pollutants may be two to five times, and occasionally more than 100 times, higher than outdoor levels.

Paradoxically, laws designed to improve energy efficiency and outside pollution don't improve indoor air quality. Tightly sealed homes constructed in the last couple decades to reduce drafts have diminished the use of fossil fuels, but if a house can't "breathe," it also can't dilute pollutants contained in building and decorating products.

While pollutants can affect people differently, the EPA warns of immediate effects including irritation to the eyes, nose and throat, headaches, dizziness and fatigue. Long-term effects can include respiratory disease, heart disease and cancer, according to the EPA.

Potential sources of indoor air pollution include central heating, cooling and dehumidification systems; household cleaning and maintenance products; outdoor sources such as pesticides; biological contaminants such as animal dander, mold and cockroaches; dry-cleaned clothing; tobacco smoke; formaldehyde from fabrics, pressed wood products and insulation; styrene found in adhesives, foam, lubricants, plastics carpets, and insulation; and paint-strippers and removers.

While this is not particularly good news, awareness is the first step to a more healthful indoor environment. Your best defense against indoor air pollution is a strong offense.

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STOP POLLUTING

First, identify and control sources of pollution to reduce and prevent indoor air contamination. This can range from changing housecleaning products to airing out freshly dry-cleaned clothing to tossing out formaldehyde-containing furniture.

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IMPROVE VENTILATION

Proper ventilation—the mixing of indoor air with outdoor air—can revitalize the air in your home and protect your health. Adequately sized exhaust fans should be used wherever moisture and combustion are present in the bathroom, laundry and kitchen. A bath fan, for example, will help to dissipate chloroform gas, which is a byproduct of chlorinated water. It also will remove excessive moisture that can lead to mold which can produce yet more health hazards.

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SMOKE IT OUT

Since cigarette smoke is one of the single greatest contributors to indoor air pollution, smoking indoors is a no-no. Similarly, fireplaces and other fuel-burning appliances (water heaters, furnaces, stoves, etc.) should be properly adjusted and vented to the exterior. Doing so will both prevent carbon-monoxide poisoning and improve the efficiency of the appliance.

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TEST IT

Do-it-yourself test kits are available for many indoor air pollutants such as lead or radon. Other indoor pollutants such as asbestos require professional testing.

The rule of thumb for lead and asbestos is that they are best left alone if in good shape and not peeling or crumbling. Asbestos or lead should not be scraped or sanded and should be removed only by a professional abatement contractor with the proper equipment. Moreover, testing should be performed after the abatement process to ensure the air quality is safe.

Radon, on the other hand, is a naturally occurring gas that is derived from uranium in the ground. Radon can make its way into a home through cracks in foundation or basement walls. Small amounts of radon can be controlled by sealing cracks with a caulking or patching compound. Higher levels might require the installation of an exhaust system to disperse concentrated amounts into outdoor air.

In either case, if you suspect that your home contains more than its share of pollutants, we suggest that you have your home tested by a pro.