Exposure to indoor air contaminants has been a problem since the first cave-dwelling humans kindled fires and established vent holes in their cave roofs to carry away smoke. Ancient native Americans constructed noncave dwellings that also provided for exhaust of stale indoor air. Even in the Old Testament, Leviticus 14:34-57 offers instruction on how to deal with mildews and molds.
The sources of indoor air pollution have changed since the days of campfires in caves, and now those sources commonly involve synthetic building materials, personal-care products, pesticides, and household cleaners. Moreover, tighter buildings--with less-permeable building envelopes, windows that don't open, and other structural changes developed in response to the energy crisis in the 1970s--have increased the number and types of contaminants released into the indoor environment, while decreasing the flow of fresh outdoor air into buildings.
Behind Closed Doors
Americans spend up to 90 percent of their time indoors, where concentrations of pollutants are often much higher than those outside. Risk assessments performed for radon and environmental tobacco smoke have shown that the health risks associated with exposure to these indoor pollutants are substantial.
A recent National Academy of Sciences report, for instance, concludes that radon is the second leading cause of lung cancer in the nation. (1) The academy estimates that about 15,000 to 22,000 cases of lung cancer and 12 percent of lung cancer deaths each year in the United States are linked to radon. By way of comparison, the U.S. Department of Transportation reported about 42,000 traffic fatalities in the United States in 1997. (2)
Environmental tobacco smoke is estimated to cause an additional 3,000 lung cancer deaths (3) and 35,000 to 62,000 cardiovascular deaths each year among nonsmokers. (4) Environmental tobacco smoke also causes a host of serious health effects in children. In particular, it annually aggravates asthma in up to a million children and causes between 150,000 and 300,000 lower-respiratory-tract infections in infants and children under 18 months of age. (5) It is also associated with 1,900 to 2,700 cases of sudden-infant-death syndrome and 9,700 to 18,600 cases of low birth weight in infants. (6)
Other studies show significant health effects from additional indoor contaminants. Carbon monoxide poisoning, for instance, is associated with the improper use and maintenance of fuel-burning appliances; it kills more than 200 people each year in this country and results in about 10,000 admissions to hospital emergency rooms. (7)
The agent that causes Legionnaires' disease, a potentially deadly pneumonia that affects 10,000 to 15,000 people each year, is associated with cooling systems, whirlpool baths, humidifiers, and other indoor sources. (8) Effects associated with environmental toxins from indoor fungi and bacteria range from short-term irritation to immuno-suppression and cancer. (9)
More recently, the National Academy of Sciences' Institute of Medicine issued a report on asthma and indoor air quality, confirming that dust mites and other allergens, microorganisms, and some chemicals found indoors are important triggers for asthma. The report also stated that preschool children exposed to either environmental tobacco smoke or house dust mites are more likely to develop asthma. (10)
In 1987, the Comparative Risk Project of the U.S. Environmental Protection Agency examined the relative risk of various environmental problems; and in 1990, the Relative Risk Reduction Strategies Committee of EPA's Scientific Advisory Board conducted a similar, extensive analysis of relative environmental risk. The resulting reports, Unfinished Business: A Comparative Assessment of Environmental problems (11) and Reducing Risk: Setting Priorities and Strategies for Environmental protection, (12) ranked indoor air pollution among the top five environmental risks to public health. …