In our increasingly polluted cities, we can at least escape the miasma of dust and chemicals in the sanctuary of our homes. Right?
Wrong. We may close the door on some outdoor pollutants, but can walk into the realm of indoor contaminants that can, in sufficient concentrations, pose a serious health threat.
Take radon: a colorless, odorless gas that occurs naturally and is found everywhere at very low levels, it nevertheless can become a problem when it gets trapped inside buildings.
It is known to cause lung cancer, and is blamed for between 5,000 and 20,000 such cases a year, or about 10% of the U.S. total, says the Environonmental Protection Agency.
Asbestos, what used to be a common insulator and fireproofer, is now recognized as a cause of lung cancer and asbestosis. Much asbestos-related disease comes from work environments, but the material is also present in many homes, especially in older buildings.
Another common home pollutant is lead, most commonly found in paint, and released into the atmosphere by burning or sanding.
There are more, but before you sell your home and take up residence in a sensory-deprivation chamber, know there are ways to detect these pollutants and reduce or eradicate them.
Tracking down indoor pollutants may begin with an unexplained health complaint. Short-term problems traceable to an indoor source may include dizziness, headaches, irritation of the eyes, nose and throat, or simply fatigue.
Such complaints may be cured simply by eliminating exposure to the source or improving ventilation. Others, however, may only show up years after long or repeated exposure.
The EPA estimates that we spend about 90% of our time indoors, and those who spend the most time inside are those who are most susceptible to indoor pollutants--children, the elderly, the chronically ill and those suffering from respiratory problems.
Devices are available to measure pollutants. Radon, for example, can be measured with charcoal canisters or alpha track detectors. State environmental agencies usually can provide information on how to obtain them.
Whether you are buying a home or just want to test your existing home, here's what to look for:
--Radon: Most commonly, it comes from the breakdown of uranium in the soil and rock on which houses are built. Test for it, but get professional advice before trying to get rid of the source; seal cracks and other openings in the basement floor; treat radon-contaminated well water by aerating or filtering through granulated activated charcoal.
The EPA says the average radon level in American homes is 1 1/2 picocuries per liter, but some homes have been found with up to 200 picocuries. Most levels in most homes can be reduced to 4 picocuries, the EPA says.
--Asbestos: Usually found in deteriorating or damaged insulation, fireproofing, or acoustical materials. Homeowners should get professional advice on removal and not disturb materials suspected of containing asbestos.
--Lead: The level of lead dust is likely to be 10 to 100 times greater in homes where sanding or open-flame burning of lead-based paints has occurred. The EPA recommends that homeowners test paint for lead if they suspect its presence.
Cover lead-based paint with wallpaper or other building materials. Replace moldings and other woodwork or have them removed and chemically treated off site. Drinking water may also be tested.
--Formaldehyde: Found in pressed-wood products and some types of foam insulation. Also in durable-press drapes, other textiles, glues and tobacco smoke. The levels in the home can be reduced by using "exterior grade" pressed-wood products containing phenol resins, maintaining moderate temperature and humidity levels, and increasing ventilation.
--Carbon monoxide: Common sources are unvented kerosene and gas heaters, leaking chimneys and furnaces, down-drafting from wood stoves and fireplaces and gas stoves. It can also leak from adjoining garages.
Reduce levels by keeping gas appliances properly adjusted, using vented gas space heaters and furnaces, installing exhaust fans vented outdoors above gas stoves, hiring professional help to clean, inspect, and tune up a central heating system.
--Organic gases: Found in household products including paints, paint strippers, solvents, wood preservatives, cleansers, moth repellents and dry-cleaned clothing. The highest levels are most likely to be found after paint stripping. Proper ventilation is the best way to reduce their levels.
--Biologicals: Including pollen and fungi; these can be produced by wet or moist walls, ceilings and carpets; poorly maintained humidifiers and air conditioners. Adequate ventilation and proper maintenance of air conditioners and humidifiers will guard against them.
An EPA publication "The Inside Story -- A Guide to Indoor Air Quality" says the levels of pollution from individual sources may not pose a significant health risk in themselves, but together, could be a threat to residents.
"Fortunately, however, there are steps that most households can take both to reduce the risk from existing sources and to prevent new problems from occurring," the agency says.