Formaldehyde. You may remember it fondly from high school biology days -- a clear liquid preservative with dead things floating in it that made your eyes sting and your nose run. I don't know what your decorating style is, of course, but I think it's safe to say that formaldehyde is not a substance most people associate with their homes.
But formaldehyde is used as an ingredient in a wide number of household products and building materials. Many of those products and materials seep, or "outgas," formaldehyde gas. And that dangerous gas can accumulate in the air inside buildings and houses.
The formaldehyde gas that builds up inside your house isn't enough to pickle you. After all, the clear liquid in the biology-specimen jar was the straight stuff. But even at levels as low as 0.10 parts formaldehyde to every one million parts of air in your house, that crummy feeling you have all the time could be your house making you sick.
"Sufficient evidence exists to conclude that indoor air pollution . . . may pose serious acute and chronic risks," the Environmental Protection Agency reported to Congress two years ago. And most indoor air-quality experts agree that the number-one problem is the same stuff as in that pickling jar. Formaldehyde is one of an extended family of chemicals referred to as volatile organic compounds. The "organic" means they contain carbon in their structure. The "volatile" means that the compounds vaporize -- become a gas -- at normal room temperatures.
If you left the lid off that jar, all the liquid would eventually evaporate and become part of the mixture of gases that make up air.
What does exposure to formaldehyde in your home air do to you? Oddly, formaldehyde affects different people with widely differing levels of severity. An estimated 10 to 20 percent of the population is very sensitive to formaldehyde, showing symptoms extremely low levels. Other people seem quite immune to the stuff, even at fairly high concentrations.
Levels of formaldehyde as low as 0.10 parts per million (ppm) can cause eye, nose and throat irritation, coughing, skin rashes, headaches, dizziness, nausea, vomiting and nosebleeds. Some people develop allergic reactions. Some people -- especially children -- develop asthma and chronic bronchitis.
People who are sensitive to formaldehyde show symptoms at levels even lower than that.
What is a "normal" level of formaldehyde? According to Richard Knights, indoor air-quality expert in Seattle, Wash., formaldehyde outdoor air is usually found at levels less than 0.01 ppm. No standard for safe levels of the stuff has been set for indoor air. But levels even lower than 0.10 ppm can be associated with symptoms of "building-related illness."
Assuming you don't have a home bio lab, from where in your home could formaldehyde be coming? The United States Consumer Product Safety Commission lists these major sources:
* Pressed wood products, especially those bound with urea-formaldehyde glues. These materials include particle board, medium-density fiberboard and interior-grade plywood. They can be used in carpet underlayment, paneling, kitchen counters, cabinets, shelves, drawers and furniture. Exterior-grade plywood, made with phenol-formaldehyde glues, gives off substantially less formaldehyde than the interior-grade plywood does.
* Durable-press fabrics, draperies, sheets and coated paper products. Cosmetics, paints, coatings and some wet-strength paper products, such as paper towels. (These probably don't contribute enough to be a problem for most people, but for those who are sensitive to the gas, they can be enough to trigger an allergic reaction.)
* Indoor combustion sources, such as gas cooking stoves, cigarettes, burning wood and kerosene -- and your car's engine, if you have an attached garage.
* Urea-formaldehyde foam insulation. This isn't used much anymore because of the high levels of formaldehyde associated with it. Most of the installed insulation is now more than 10 years old, and so it has released most of the formaldehyde it is likely to.
If you have unexplained symptoms -- chronic respiratory infections, headaches, stuffiness or chronic fatigue -- or if anyone in your family has asthma, if you feel better when you're out of the house or when all your windows are open, you should probably have your house tested for elevated levels of formaldehyde. Call your local public health department for a list of labs that can help you, or look in the Yellow Pages under "Laboratories: Analytical."
If you don't have any symptoms, you probably shouldn't bother having your house tested. But you should certainly take a hard look around to identify possible sources of the gas. Once you've identified them, you can take reasonable steps to reduce the amount of formaldehyde coming from them.
Reducing formaldehyde need not call for drastic measures. But telling you how to go about it is going to require more space than I have left here. So tune in next week to find out how to keep your house from becoming that pickling jar.
(Have a question of general interest that can be answered in this column? Please send it to Susan McGrath at P.O. Box 121, 1463 E. Republican St., Seattle, Wash. 98112.)