Here’s what top experts suggest you do to fight air pollution from the inside: Check your detection devices. Carbon monoxide and smoke detectors should be installed in a central hallway on each level of your home as well as in the basement, and a smoke detector should also be installed in each bedroom. (Check your local building codes for exact placement.) If your detectors aren’t integrated into a burglar alarm system, think about upgrading to wirelessly linked units so that if one detector gets triggered, they’ll all ring and wake up the whole family. First Alert’s OneLink Series SCO500 ($64; amazon.com), for example, provides both smoke and carbon monoxide detection, and a voice alert indicates where the alarm originated. Test for radon. Radon is an odorless and invisible radioactive gas that’s carcinogenic over the long term—it’s the second-leading cause of lung cancer in the United States—and has been found to be present in homes across the country. Radon gas is produced as a result of the natural breakdown of uranium in soil. The gas rises from the ground and seeps into your house through foundation cracks. Fortunately it’s easy to detect. You can buy a test kit at a hardware store for about $14, including lab fees and a postage-paid mailer. If results reveal gas levels above the EPA-recommended 4 picocuries per liter, hire a remediation company to install a system for venting the gas away from your house (about $1,200). Service your heating system. Homes with heating and air-conditioning systems rely on ductwork to deliver the warmed or cooled air, and because out of sight can mean out of mind, it’s easy to forget about maintaining them. But these ducts should be cleaned every 5 to 10 years to remove dust, pet dander, pollen, and mold that can collect in the system and spread throughout the house whenever the heat kicks on, says Jeffrey May, a Tyngsborough, MA, indoor air quality inspector, an organic chemist, and the author of My House Is Killing Me! This is not a do-it-yourself job. You’ll need to hire a professional, but be savvy about which company you choose. “Pick someone who uses brushes instead of only vacuums or chemicals and cleans the blower unit—and the air-conditioner coil if you have central air,” May says. You’ll pay about $500 or more if you have central air and need the blower and coil cleaned. You should also have your heating system serviced annually to ensure that it’s burning cleanly and not causing exhaust to reenter the house as back draft. Clear the air. If you have forced-air heating, replacing the furnace filter four times a year will not only make your system more efficient but will go a long way toward filtering dust, mold spores, and other contaminants. But instead of using the standard flat fiberglass filters, choose pleated products (they look like accordion-folded paper) with a MERV-8 rating, and seal any gaps around the filter-access opening with duct tape. Pleated filters are more effective than fiberglass at trapping the smaller particles you’re likely to inhale. If a family member has allergies or chronic respiratory ailments, hire a contractor to upgrade your system with a media filter such as the Aprilaire Whole-House Air Cleaner, which turns the heating system into an air purifier. The project can cost around $1,000, and you’ll have to replace the $50 filter annually. Also, if you don’t have one already, add a humidifier to your furnace. “Dry winter air dehydrates the nasal and lung linings, making people more susceptible to asthma, congestion, and viral infection,” says Jay Portnoy, MD, chief of the allergy and asthma department at Children’s Mercy Hospital in Kansas City, MO. Clean the chimney. Every five years or so, you should hire a chimney sweep to clean and inspect your flues. But if your fireplace is used on a regular basis, have it done every year. A clogged flue can cause a potentially deadly exhaust backup and become a fire hazard if too much flammable soot builds up inside. More from Prevention: 5 Invisible Toxins In Your Living Room Find and fix leaks. Watch for wet areas inside your house, especially under plumbing fixtures, in the attic eaves, and in the basement. Mold will grow on any organic material (such as wood, wallboard, or even dust) that’s wet for more than 72 hours. When that mold releases its spores (which are like invisible airborne seeds), they can trigger allergies, asthma, and respiratory illnesses. If you find moisture, fix the problem immediately, and then eradicate any mold you can see. “Mold does die when it dries out, but the allergens will continue to cause reactions in people with a sensitivity to them—and may even trigger allergies in people who don’t already have them,” says Jordan Fink, MD, professor of medicine and pediatrics in the Allergy-Immunology Program of the Medical College of Wisconsin. If you have a large mold infestation, hire a remediation company to remove it. Otherwise, don an N-95 respirator, rubber gloves that extend up your forearms, and safety goggles without ventilation holes; open all the windows; and scrub away the mold using a cleaner that contains bleach, such as Tilex, or a solution of 1 part bleach to 10 parts water. When to clean appliances:

Heating system Ducts should be cleaned every 5 to 10 years to remove dust, pet dander, pollen, and mold that can collect in the system.Smoke alarm If your detectors aren’t integrated into a burglar alarm system, think about upgrading to wirelessly linked units. If a detector is triggered, it’ll wake up the whole family.Windows Open them when you can. If they’re shut tightly all winter, contaminants get trapped, decreasing air quality.Range hood A hood that blows air into the room filters grease but dumps other pollutants into your home. Install a vent to carry the exhaust outside.Stove top When possible, cook on the back burners, which tend to draft more effectively up into the hood.Painting Don’t paint in winter. Some products release volatile organic compounds, so it’s better to use paint in spring, when you can open windows to ventilate.Carbon monoxide detectors Place one in a central hallway on each level of your home, including the basement.Garage Never warm up your car in the garage. Even with the doors open, there’s a chance the deadly carbon monoxide could linger in the garage and even spread into the house if it’s attached.Plumbing Watch for wet areas under fixtures. Mold will grow and can release spores that trigger allergies and asthma.Fireplace Clean and inspect your flues every 5 years. If your fireplace is being used on a regular basis, have it done every year.

4 Habits For A Healthy House:

  1. Run your range’s vented hood every time you cook so that you eliminate steam, smoke, food particles, and the carbon monoxide created by gas cooktops and burned food on any kind of stove, says Jordan Fink, MD. Otherwise, those particles become indoor air pollution that your family will be inhaling for hours. “Use the high fan setting when you can put up with the din,” he says. “And when possible, cook on the back burners, which tend to draft more effectively up into the hood.” If your hood blows air into the room, it’s just filtering out grease before dumping other pollutants into your living space. To carry the exhaust outside, consider installing a vent, which will likely cost $500 to $1,500.
  2. Never warm up your car in the garage. Even with the doors open, there’s a chance the deadly carbon monoxide could linger in the garage and even spread into the house if it’s attached.
  3. Wait until spring to paint or to buy furniture, upholstery, or carpeting. These products, especially when they’re new, release volatile organic compounds such as formaldehyde, acetone, toluene, and benzene. It’s better to place them in your home when you can open the windows to ventilate. Or buy products with no-VOC certification from Greenguard or Green Seal. And never use air-freshening sprays. “They’re the most common cause of high VOCs in houses,” says Jay Portnoy, MD.
  4. Always turn on the exhaust fan in the bathroom (even if the noise is annoying), or hire an electrician to install a fan if you don’t have one. Without a fan, moisture will condense on cold surfaces, including those hidden in the walls, fostering mold growth. Check that the fan is venting to the exterior, not the attic. If moisture winds up in the attic, so will mold. A handyman can add a duct for under $300. More from Prevention: 10 Toxic Rip-Offs You Should Never Buy