Health-related problems in your home aren't always easy to spot (unless, alas, you have critters). Consult this guide to uncovering hidden hazards.
Why they can be dangerous: Flies transport bacteria, such as salmonella and E. coli, as they feed, and can also spread conjunctivitis and cholera, says entomologist Ron Harrison. Roaches can contaminate food and trigger asthma, while mice can transmit parasites and germs that cause food poisoning through their droppings.
How to protect yourself: For the occasional housefly or two, flypaper works. So does a swatter with a thin wire stem and a tight mesh head. For an infestation, try the chemical-free Insectalite light trap, which lures flies onto a concealed glue board. To keep roaches at bay, don't leave unwashed dishes in the sink, uncovered food on counters, or pet food out overnight. And instead of using those little black disks that contain chemicals, try disposable, nontoxic glue traps. For mice, the Centers for Disease Control and Prevention (CDC) recommend a simple snap trap baited with peanut butter. Mice can squeeze through areas the size of a dime (eek!), so you'll need to plug any gaps in your walls, molding, and floorboards with steel wool.
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Why it can be dangerous: Asbestos is a durable, fibrous mineral that strengthens products and provides insulation and fire resistance. It was used in various residential applications before the late 1970s, when the U.S. Consumer Product Safety Commission (CPSC) banned the inclusion of the material in certain items. (The Environmental Protection Agency [EPA] banned all new uses of asbestos in 1989, but products that were on the market may still contain it.) Asbestos fibers, when airborne, can become trapped in the lungs, increasing the risk of cancer, says lung-disease specialist Norman Edelman. Prolonged exposure is even more harmful.
How to protect yourself: Your home may have been inspected in the past, but deterioration over time or a remodeling project could have caused previously encapsulated asbestos to become a danger. Be suspicious if you notice crumbling fibers around roofing or siding materials, acoustical ceiling or vinyl floor tiles, or cement water pipes. Also check your home's original building plan; some builders used the abbreviation ASB to note where asbestos was applied. If you think you might have asbestos (don't touch it), contact a licensed asbestos inspector, who will take samples and send them to a lab to be analyzed. Costs for analysis vary, but plan to spend several hundred dollars. Asbestos removal requires a call to a certified or licensed asbestos contractor and can run you several hundred to thousands of dollars, says asbestos-board executive director David E. Dick. For a list of state asbestos contacts, log on to epa.gov/asbestos/pubs/regioncontact.html.
3. Carbon Monoxide
Why it can be dangerous: When emitted in a small or poorly ventilated area, this invisible odorless gas "can quickly poison you by preventing oxygen in your lungs from reaching your tissues. It can cause damage to the brain immediately or several days after an apparent recovery," says physician Richard Moon.
How to protect yourself: "Install carbon monoxide alarms on each floor of your home and near each sleeping area," says Patty Davis of the CPSC. Have your heating system and fuel-burning appliances inspected annually. If you use an unvented space heather, get one equipped with an oxygen depletion sensor (ODS), which will shut off the appliance when it detects dangerously low levels of oxygen. "And leave doors open to rooms with actively used gas- and wood-burning appliances," such as a furnace, a woodstove, or a fireplace, says Kurt Kneen of the National Safety Foundation.
Why it can be dangerous: More than 20,000 radon-related lung-cancer deaths occur in the United States each year, making it the second leading cause of lung cancer, after smoking, according to the EPA. Radon, a colorless, odorless radioactive gas, forms when uranium breaks down in soil, rock, or water. It is usually found in a home's lower levels, where it enters via foundational cracks or groundwater.
How to protect yourself: Radon has no visible signs, and it can build up over time. So even if you've had a radon test in the past, perhaps during a home inspection, you should still test for it every few years or after any major home renovation, says epidemiologist R. William Field. A long-term kit (about $30 at hardware stores) will measure radon levels in your home for 90 days or longer to ensure an accurate reading. (Short-term kits are sold, but stick to long-term kits because they better reflect the average radon concentration.) After sending the test to a lab, you should receive results in a few weeks. If your radon level measure four picocuries per liter or higher, contact a state-certified or licensed radon contractor to install a radon-reduction system, which will filter and vent radon outside your home. Prices range from $1,000 to $1,500, including the contractor's fee; to find a contractor, call the National Safety Council Radon Helpline at 800-557-2366.
Why it can be dangerous: Most molds, including the dreaded black mold, are harmless unless they're disturbed, which causes spores to go airborne. And though thousands of mold strains exist, only a handful generate dangerous mycotoxins. Touching or inhaling spores can trigger an allergic response; exposure can result in hay fever-like symptoms, a skin rash, or an asthma attack.
How to protect yourself: "Mold is easy to control," says biologist George Bean. "You can usually handle it on your own by regulating humidity." You can tell if your home's humidity is too high if you noticed condensation on windows. To maintain an ideal 60 percent relative humidity, use a dehumidifier. If you machine comes with a gauge, great; if not, humidity can be measured with a hygrometer. To clean mold-infested surfaces, "use a product that leaves an antimicrobial residue behind, " says Bean. During cleanup, wear rubber gloves, goggles and a disposable N-95 respirator (a mask that fits over you nose and mouth to filter out airborne hazards). Other things you can do to prevent mold: Replace rubber gaskets on leaky faucets, reinforce pipes with silicone caulking (do this yourself or call a plumber), and buy a freestanding HEPA air purifier to lessen spore counts.