Clean Air at Home

Activists often use the image of the canary in the coal mine to warn of potential threats to the environment. When it comes to the quality of indoor air, that´s more than a well-worn cliche

  • Peter Jaret
  • Feb 01, 2000
Veterinary experts have long cautioned that pet birds can be poisoned by fumes from common household chemicals, burning food, even pots and pans. "For safety, please keep pet birds out of the kitchen," cautions the label of one leading brand of nonstick cookware. "Birds´ respiratory systems are sensitive to many kinds of household fumes, including the fumes from overheated nonstick pans."

Fortunately, the levels of emissions from overheated cookware apparently are not high enough to harm people. But that´s no reason to be sanguine: The evidence that our own health may be at risk from indoor air pollution is growing. Recent studies by the Environmental Protection Agency (EPA) have found that indoor air quality is two to five times worse than outdoor air. That´s troubling because Americans now spend 90 percent of their time indoors, according to the EPA.

Not only that, the quality of the air we breathe inside our homes and offices has actually been on the decline, even as the quality of outdoor air in many locations has improved. Researchers have long known that our drive to make houses more energy efficient has exacerbated the problem. "By sealing windows and doors to keep inside air in and outside air out, we´ve reduced the air-exchange rates by a factor of two or more in many new houses," says Richard Corsi, associate professor of civil engineering at the University of Texas and one of the country´s leading experts on indoor air quality.

To keep costs down, some builders also have cut corners on ventilation systems, making matters worse. "When there´s a potentially toxic chemical indoors, it´s much more likely to cause trouble," he adds. Meanwhile, the sources of trouble are increasing. Some molds and fungi are taking advantage of our indoor habitat. And new building materials and synthetic fabrics continue to introduce all kinds of new chemicals into our houses.

This time of year, when houses are sealed up as tight as Tupperware in many parts of the country, indoor air pollution is at its peak. "Many of the things we have under our roofs, from wall-to-wall carpeting and kitchen cabinets, to cleaners and candles, release potentially toxic substances," says Corsi.

Last year, researchers at Battelle Memorial Institute in Columbus, Ohio, released a long list of household items that emit formaldehyde, which is classified by the EPA as a probable human carcinogen. The Battelle list included better-known culprits, such as particleboard and insulating foam, as well as some eye-openers such as plastic-laminate counters and acid-cured resins used to finish floors. The resins not only emit up to 1,000 times as much formaldehyde as particleboard during the first 24 hours of drying and continue to give off high levels for a week or more.

But man-made objects are only part of the problem. In 1998, researchers at Texas Tech University Health Sciences Center in Lubbock investigated 48 schools where people had complained about headaches, weakness and breathing difficulties. The buildings, they found, were overrun with two common molds, Penicillium and Stachybotrys. "The higher the level of molds, we found, the worse the symptoms," says Daniel Cooley, director of the center´s Indoor Air Quality Laboratory. His team demonstrated that common molds cause allergic symptoms and can damage the immune system.

Some scientists now think molds, which are a form of fungi, may be the culprits behind chronic sinus infections, or sinusitis. Last September, scientists at the Mayo Clinic in Rochester, Minnesota, found that among 210 patients with the stubborn problem, 96 percent had molds and other fungi lurking in their noses. "Our studies indicate that, in fact, fungus is likely the cause of nearly all of these problems," the researchers reported.

Exactly how dangerous the situation is no one knows, partly because levels of contaminants vary widely from place to place. Researchers do know that formaldehyde has been shown to burn the throat and eyes and cause breathing difficulty in sensitive individuals. Long-term exposure has been linked to asthma, according to the EPA. Animal studies show that formaldehyde can cause cancer, which has helped indicate that it probably does the same in people. But because human cancers develop slowly and have multiple causes, researchers haven´t yet turned up direct evidence implicating indoor air contaminants.

The reason researchers are now sounding the alarm is that levels of these potentially dangerous substances are on the rise. In some structures, the problem is so bad that nothing short of tearing them down and rebuilding can make them safe to live or work in, says Cooley. Luckily, that´s the exception. In most houses, taking a few simple steps can dramatically reduce indoor air pollution; they don´t have to involve creating drafts that add to heating or air-conditioning bills.

Some tips are the usual commonsense advice: Make sure stoves, heaters and fireplaces are properly vented. Always use exhaust fans if you cook with gas. If your house has an attached garage, never idle the car while it´s inside. Periodically clean air conditioning and heater filters to prevent mold growth. To remove dampness from a basement or attic, install a dehumidifier and ventilation fans.

Besides the basics, recent research has turned up some unexpected sources of potential indoor air pollution. Here are some of the most surprising:

Dishwashers, washing machines and showers: Appliances and fixtures that heat and spray water can strip chemicals out of the water, releasing them into the air to be inhaled. Such contaminants include toxic chemicals that form when chlorine is added to water supplies or to the water in a washing machine. They also include pollutants that sometimes show up in water, such as benzene and naturally occurring radon, both known carcinogens. In experiments conducted in 1999 by Corsi and colleague Cynthia Reed, dishwashers were among the worst offenders in releasing chemicals from water to indoor air. Corsi´s advice: "Wait until the dishwasher has completely cooled down before you open it. And always turn on the exhaust fan or open a window before, during and for 10 or 20 minutes after you take a bath or shower."

Permanent-press materials: Last year, Battelle researchers reported that permanent-press clothing and drapes, as well as wet fingernail hardeners and polishes, release unexpectedly high levels of potentially toxic vapors. The experts´ advice: Wash permanent-press clothing and drapery as soon as you buy it. Open windows or doors before and while using any paints or other chemicals.

Wall-to-wall carpeting: Experts have long warned that some adhesives and backing used in indoor carpeting release a potentially dangerous gas called 4-phenylcyclohexene, or 4-PC (it´s responsible for the familiar "new carpet" smell). Now they´re learning that carpeting also serves as a reservoir for other toxics, such as pesticides and chemicals used to dry-clean clothing. "Carpeting adsorbs these chemicals and slowly releases them over time," says Corsi. That´s a special concern if you have very young children, who not only spend most of their time at floor level but whose developing bodies are especially vulnerable to toxic chemicals. One solution is to get rid of wall-to-wall carpets and instead use area rugs, which can be cleaned periodically. If you can´t live without wall-to-wall carpets, choose a brand certified by the EPA.

In their own home, Corsi and his wife have made several changes, such as giving up burning scented candles, another newly identified source of potentially toxic contaminants. Even unscented candles can give off lead, which sometimes is used in wicks. "There´s no easy way to eliminate all potential hazards," Corsi admits. "But a few precautions can go a long way toward making indoor air healthier to breathe."

California writer Peter Jaret is a frequent contributor to "Your Health."

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