Because, after all, this is your home. It’s clean, and therefore it’s healthy. Or, is it? Odds are the answer is no. The simple fact is that most of our homes are full of air that has the potential to make us sick. In fact, the U.S. Environmental Protection Agency (EPA) says that mounting scientific evidence shows that the air inside our homes is often more polluted than that outside. Whether it’s off-gassing from paint, furniture or mattresses or mold spores from a wet basement, chances your home could be making you sick.

Heating and Cooling System
If your home had a pulse, the furnace would be its heart. All those ducts and vents that circulate air throughout your home work much like your own circulatory system. And if you have leaks in your ducts, or if they are clogged up with dust or mold, that’s going to affect the health of your entire home.

Your forced air heating system works by sucking air through return vents that run through your house, heating it and then blowing that air back into your home. The return vents have filters that keep out the dust, allergens, mold spores and carpet fibers that you don’t want in your air. But the problem is that when your furnace kicks on, it sucks air not just through the filtered vent but also through all the leaky points in your ductwork.

“In a brand-new house, you are looking at probably around 30 to 40 percent leakage,” which means that roughly a third of the air being blown through your system is unfiltered, says Alan Finkel, CEO of Los Angeles-based Green Life Guru, a home inspection firm. “In a house that was built 20, 30, 40 years ago, it is 60 percent.”

If you have problems you are unaware of—such as mildew and mold in the crawl space, asbestos lingering in the attic or feces from mice or cockroaches—those particles are being sent unfiltered into your ambient air. Sealing off these leaks in your heating and cooling system can help reduce your risk of cancer, allergies and asthma.

Cleaning your ducts is also an option to consider, especially in new construction. “I would say in 95 percent of the new construction that I look at, the entire duct system is completely filthy before people ever move in,” says Jeffrey C. May, author of My House is Killing Me (The Johns Hopkins University Press, 2001) and certified indoor air quality professional (CIAQP). “The ducts are full of sawdust and drywall dust. And then when the cold damp air and the moisture get into the system during the air conditioning cycle, everything gets moldy.”

Your Water Supply
If you have well water, you must have it tested annually for contaminants such as E. coli and arsenic, a known carcinogen, says microbiologist Kelly Reynolds, Ph.D., professor at the University of Arizona Mel and Enid Zuckerman College of Public Health in Tuscon, Ariz. And if you have municipal water, don’t consider yourself off the hook, she says. “We estimate that 19 million illnesses occurs in the U.S. every year due to germ exposure from tap water,” Dr. Reynolds says. “We get sick, but we typically do not die from these exposures. We believe that if you could have simple interventions to improve the quality of your water, you could certainly improve the quality of your life and improve your health.”

Water treatment plants purify water and make it safe for drinking, but they cannot guarantee that that water remains completely contaminant-free as it makes its journey to your tap. That’s why people with compromised immune systems are advised not to drink tap water, Dr. Reynolds says.

An in-home water treatment system, such as reverse osmosis, that is guaranteed to not only filter impurities but also kill bacteria is the best way to make your water safe for drinking, Dr. Reynolds recommends.

Choices You Make
Simple things, like keeping your home as germ-free as possible, can help to reduce your family’s chance of getting sick. “You need to vacuum regularly to eliminate dust,” Dr. Reynolds says. “Dusting also removes germs because they do attach to dust particles.”

Because produce can carry many of the same bacteria found in raw meats, you need to wash these items well before eating or cooking them, she adds. And when cleaning your home’s bacteria “hot spots,” namely the kitchen and bathroom, Dr. Reynolds recommends using cleaners that contain disinfectants that kill germs.

But you can keep your home sparkling clean and still have indoor air quality issues, mainly from the off-gassing of items you bring into the home. For example, formaldehyde is found in everything from your mattresses to that pressed board bookcase. Formaldehyde has a pungent odor that can cause watery eyes, a burning sensation in the airways and, at high concentrations, asthma attacks. It is also a possible carcinogen, according to the EPA.

But formaldehyde isn’t the only chemical off-gassing inside your home. Carpeting, paint varnish, aerosol sprays, cleansers and disinfectants, air fresheners and dry-cleaned clothing all emit organic gases that can cause eye, nose and throat irritation; headaches; nausea and damage to the liver, kidney and central nervous system. Some of these elements also cause cancer in animals although human studies have not been definitive.

Opt for furniture made from real wood, VOC-free paints, all-natural cleaning products and carpeting made from natural wool. Reclaimed wood furniture—or items made from older, reused materials—will also have less VOCs because they have already off-gassed.

Adopt these solutions and the health of your home will no doubt improve. But whenever you’re feeling like you really need a breath of fresh air, just open a window. Filling your home with fresh air is one of the easiest and most effective ways of being able to breathe easy.