starShortly after Rick Courson built his home on Puget Sound's Bainbridge Island with the usual building materials, bad things started happening. His family began having low-grade illnesses, and over time the symptoms became more serious -- including increases in heart rate, kidney distress and asthma attacks. Courson noticed that the symptoms would go away in the spring and return in the fall, when the weather pushed them back indoors for most of the time. Finally, the kids' pediatrician suggested that they were victims of poisoning, and Courson traced the problem to the carpets. "We discovered that our house was, in fact, killing us," Courson said.

We usually associate air pollution with smokestacks and tailpipes, not with the inside

of our homes. But the air in out homes can be two to five times more polluted than outdoor air. What causes indoor air pollution? There are obvious sources, such as tobacco smoke and wood smoke from a poorly drafting fireplace. Malfunctioning gas stoves and furnaces can release carbon monoxide into living spaces. In some regions, radon is a concern. Then there are common biological contaminants, including pet dander, mold and dust mites.

Other sources of indoor pollution are less obvious but may affect our health. Many modern building materials and furnishing – including some types of insulation, plywood, paint and even upholstery fabrics – are made with chemical that are released (off-gassing) over

time into the air we breathe. Depending on the product, these chemicals can include formaldehyde, acetone, chlorinated solvents, phthalates, benzene, and a host of other problematic compounds.

There is so much we don’t know about the effects of indoor air pollution on our health. And there’s suspicion that the growing incidence of respiratory illnesses such as asthma, especially among children, could be linked to indoor air pollution.

The most effective way to combat indoor air pollution is to keep out the offending materials in the first place. In many cases, there are healthier substitutes for suspect building