Did you know that the air inside your house could be making you sick? In fact, it may even be causing developmental problems in your children.

If your home is like most others, the air in your house is probably five to ten times worse than the air outside, says John Bower, founder of The Healthy House Institute, Bloomington, Ind.

And no one type of house is safer than others, unless you're one of the few homeowners to have taken special steps to limit the chemicals, toxins, allergens and other unhealthy freeloaders lurking throughout the house.

Environmental health specialists say even though research has demonstrated the prevalence and threats that indoor air causes, there has been little movement to reverse the tide of unhealthy homes.

"You could be poisoning your kids without even knowing it," says Brian Sullivan, spokesman for the U.S. Department of Housing and Urban Development (HUD). The department's Office of Healthy Homes and Lead Hazard Control is one of the organizations banging the drum on the dangers of lead paint and dust poisoning and other residential health issues.

Unhealthy House Guests
But lead-based paint is just one of a plethora of dangers possibly lurking in your home. Other unwanted occupants include carbon monoxide, radon, mold, mildew, dust mites, pet dander, formaldehyde and other gases released by man-made products. According to Bower, author of "The Healthy House Answer Book" and other books on the subject, these are a sampling of your home's unwanted guests.

Other intruders include asbestos in older insulation and other housing products, mercury once used in paint and drywall compound, radioactive waste in some smoke detectors, air-borne particles released from tap water-based humidifiers, and the dozens of cleaning products stored in the kitchen or basement. Keep in mind, it's easier to get your unwanted mother-in-law to leave than it is some of these denizens.

"All of us would like to have simple solutions, and there are some, but there are solutions that don't have easy answers," Bower says.

The Trouble with Older Homes
Unfortunately, there's not a certain type of home or even part of the country where the living is easy or healthier when it comes to indoor air, according to the Healthy Indoor Air for America's Homes' Michael Vogel.

Each type of home and locale brings with it unwanted visitors, says Vogel, executive director of the consumer-focused initiative, sponsored by U.S. Environmental Protection Agency, the U.S. Department of Agriculture and Montana State University. But, the bedroom and basement are particularly prone to cultivating airborne health hazards.

"In older homes, you're definitely more likely to find lead-based paints and asbestos," according to Vogel, also a Montana State University professor. Banned for residential use since the 1970s, asbestos and lead-based paint still exist in many homes. Left undisturbed, these contaminants are generally safe and cause no health problems, experts say. However, if disturbed and released in the air during home remodeling projects, lead or asbestos dust can be dangerous.

For example, lead poisoning can damage the brain and permanently effect other organs, and is tied to reduced intelligence and behavioral problems. More than 800,000 American children younger than age 6 have lead blood levels of concern, reports the Centers for Disease Control and Prevention.<

And older homes are more likely to have older fossil fuel heating systems, which pose problems with carbon monoxide and other dangerous gases. However, inhabitants of homes heated by natural gas and newer homes are still at risk. For example, hot water heaters or other appliances not properly venting will emit harmful gases. "Gas ranges and stoves can produce extremely high levels of carbon monoxide," Vogel adds.

"Carbon monoxide is probably at the top of the list [of health hazards]," relating to bad indoor air, says Dr. Clifford Mitchell, an assistant professor in environmental health sciences at the Johns Hopkins School of Public Health. From a public health viewpoint, lead and asbestos are top concerns, as well as so-called bio-aerosols, such as dust mite and cockroach, that cause or trigger respiratory problems.

"In older homes, which are going to be remodeled more often, you'll find more dust and more problems with mold [too]," Vogel says. Older homes don't have a monopoly on mold and mildew, both major sources of allergies and asthma, but are more susceptible to these invaders, as are homes in the Southeast and Pacific Northwest because of humidity. However, humidifiers and water seepage can attract mold and mildew in dry areas.

Newer Homes: Built to Trap Chemicals
"For years, a lot of the focus has been on lead and asbestos in the home, but the more recent emphasis is on indoor allergens and asthma," says Dr. Darryl Zeldin, who heads the National Institute of Environmental Health Sciences' clinical studies program and director of its asthma program. One key suspect for the rise in prevalence of asthma and allergies, which impact nearly a quarter of Americans, are allergens in the home.

Newer homes are built tighter, often without proper mechanical ventilation, trapping the unhealthy chemicals used to treat the flooring, kitchen cabinets and other products builders typically outfit in houses.

"The particle board and plywood under the nice cherry kitchen cabinets is just loaded with formaldehyde," Bower explains, adding that it doesn't go away. Furthermore, the finish used on the cabinets by manufacturers contain much higher doses of formaldehyde, so large that it does burn itself out after six to 12 months.

Moreover, newer and tightly built homes trap the man-made materials and furnishings in which we fill our homes, from building materials to upholstered furniture to synthetic mattresses to household cleaning products.

How to Create Healthier Indoor Air

Whether you've thought about it or not, the number of things conspiring to make your home's air unhealthy is daunting. Even the most motivated of homeowners wanting to clean up the air in the house can become overwhelmed or even depressed by the task.

Both Vogel and Bower say that homeowners don't have to spend much to have or maintain a healthy home. Besides having accurate and reliable information (there's a lot of bad information and supposed fixes someone is willing to sell you), "just good preventative types of activities like good housekeeping" is effective, Vogel says.

• Keep a clean home: Regular housecleaning and vacuuming will help keep many allergens at bay. Most vacuums, however, spew allergens living in your carpets into the air because of porous vacuum filters. Experts recommend high-efficient filters for vacuums or outfitting your home with a central vacuum. Washing bedding regularly in hot water is another excellent way to reduce such problematic allergens as dust mite, cockroach and cat dander, Zeldin says. Removing shoes in your home prevents tracking in unwanted squatters, including dirt, lead, dust and animal feces.
• Maintain your home's systems: Have heating systems checked for possible carbon monoxide and other gases, as well as the fireplace, the air conditioning unit and gas appliances, such as ranges and dryers. "In a northern climate, the No. 1 thing … have your systems checked periodically," Vogel suggests. Installing carbon monoxide detectors is an inexpensive way to prevent death.

• Prevent water intrusion into your home: Unwanted water is a sure sign of potential health problems, Mitchell warns, inviting mold and mildew. The resulting impact can be particularly dire for people with respiratory problems. Keeping gutters clean and sloping dirt away from the house are two easy ways to discourage water seepage. Fix leaky pipes quickly and install exhaust fans in the kitchen and bathrooms to prevent moisture build-up. Water and moisture encourages these and other biological pollutants.
• Think before starting remodeling projects: Whether it's painting a room, knocking out a wall or undertaking a host of other projects, educate yourself to possible risks to you and your family. Homes built before the late 1970s are likely to contain cancer causing lead-based paint and asbestos. Left alone you'll be all right; disturbing them creates potential problems. Hire only contractors that employ lead safe or asbestos safe practices if your home is deemed at risk.
• Know when to hire an expert: Even the most capable do-it-yourselfers should defer to professionals when checking gas and heating appliances. Let experts seal duct work as this impacts ventilation and can acerbate chimney problems. "If done wrong," Bower says, "you could be dead by morning."
• Consider what you clean your home with: Look at the cleaning products under your kitchen sink. "Many contain hazardous wastes," Bower warns, "legally you can't put them in a landfill, but we use them throughout the house." There are organic cleaners, but they are harder to find and in some cases may not work as well.

"We all fit under a Bell-shaped Curve," Bower says. "Some of us are more sensitive than others." There should be a reason to take action to clean up indoor air, instead of just doing it willy nilly, Vogel suggests. Telltale signs to undertake changes include presence of a constant odor, stuffy air, dampness or water seepage or a family member consistently feeling ill inside or feeling better outside. For those with chronic medical conditions, such as asthma, emphysema and other respiratory conditions, taking quick action is imperative for health reasons.

Finally, experts say there's an industry developing to take advantage of people's fears in this area. Don't be taken. "Is some cases, the fix is worse then the problem," Mitchell cautions.