Some sources of indoor allergens are well known: mattresses and bed pillows infested with dust mites, for example, and carpeting that contains pet dander. Others are more secret. If you or anyone in your family has allergies or asthma, getting to know the more unrecognized allergen sources and where they are located can help you take steps to reduce the indoor triggers. Dog beds can become infested with dust mites and their allergens. Your beloved companion’s fur is then exposed to the allergens—and you are, too, when you cuddle the dog, or if you allow the dog to sleep on your bed. Use a blanket or thin quilt instead of a thick dog bed that can’t be washed, and wash the blanket or quilt at least once a month.
Fish are often the pet of choice when children are allergic to dogs or cats. Unfortunately, dust mites can colonize a fish-tank cover, where there is warm, moist air and plenty of food in the form of protein-rich fish flakes. Don’t put a fish tank in your allergic child’s bedroom, and wherever the tank is located, always keep the cover and tank rim free of dust and fish food.
Feathers produce fragments that can be irritating to breathe and may contain microscopic granules of bird allergens. Families with allergic or asthmatic members should avoid feather-filled bedding or furniture. Feathers are also a problem when attached to a living bird. Several types of respiratory diseases, including hypersensitivity pneumonitis, are associated with frequent contact with birds and their microscopic dander. So it’s not a great idea to have a pet bird in the house, either, especially cockatiels.
Jar candles (regardless of the type of wax inside) produce a lot of soot that can stain walls and ceilings. Soot particles are small enough to remain permanently suspended in air and to be breathed deep into the lungs. And a soot particle can also become a surrogate allergen (carrying the allergen on its surface). If you find you can’t give up burning candles altogether, burn tapered candles, which typically produce less soot.
Kitchens and laundry areas can contain allergen sources. Always vent a dryer to the exterior, because lint or excess moisture can build up indoors, leading to condensation and mold growth on cool surfaces. And if your dryer hose is leaky, lint containing potentially irritating laundry chemicals can build up behind the appliance and enter the home on dryer airflows. If your refrigerator has a drip tray that hasn’t been cleaned for a while, it may be full of mold, yeast and bacteria. Remove the tray once or twice a year for cleaning. If the tray is plastic, add three tablespoons of salt to inhibit microbial growth.
Basements are prone to elevated relative humidity and mold growth. In the winter, up to a third of the air in a house rises from the basement, so basement mold is a potential health concern. It’s not always easy to see surface mold growth. Shine a bright flashlight parallel to a surface to look for oval mold colonies. In an unfinished basement, mold can grow on the bottom of a shelf or workbench, on the ceiling joists or on dust captured in exposed fiberglass insulation. In finished basements, mold can grow on the lower foot of wooden furniture legs, on furniture surfaces facing cooler floors or walls, and in dust captured in a basement carpet. Control the moisture that leads to mold by dehumidifying a finished or unfinished basement in the humid season. Measure the relative humidity (RH) with a hygrometer, and keep the RH at or below 50%. And whether in use or not, finished basements must also be consistently heated in the cooler season, with the thermostat set no lower than 60°F.
An air-to-air heat exchanger helps flush out a home’s stale air and lets the fresh air in, but because cool air and warm, moist air flow by each other inside the heat exchanger, condensation can occur. Most air-to-air heat exchangers have inadequate filtration and fill with dust, dead bugs and pollen, leading to mold growth. By-products of this biological growth—including unpleasant smells—are carried into the house on the incoming air stream. If you have an air-to-air heat exchanger in your home, install a supplemental MERV-8 (minimum efficiency rating value) filter on both the intake duct for the house air and the intake duct for the exterior air. And clean the heat exchanger at least twice a year to avoid dust build-up.
Real vigilance against household allergens may result in increased energy use, but preventing mold growth and keeping a home’s indoor air clean is essential to protecting your family’s health. And properly maintaining appliances and filters is always energy-wise in the long run.