Americans spend 90 percent of their time indoors, but have you ever thought about the purity of the air that you are breathing as you sit inside your home, office or even a restaurant?

Indoor air quality is considered to be the fourth greatest pollution threat to Americans by the Environmental Protection Agency (EPA).  Even if you can never see, and can't always smell, the chemicals inside your home, they are there.  It comes from cleaning products, drycleaning chemicals, plastic products like computer keyboards, furniture, paint, carpeting and more.

With the help of the Greenguard Environmental Institute, part of Underwriters Laboratories, " Good Morning America" set out to investigate exactly what kind of threat indoor air pollution posed to the average person by setting up a child's nursery with a new crib, changing table, rocker and decorations.

Seven days of testing later, the results were in.  The air in our new nursery contained 300 different chemicals  - compared to just two right outside the same house.  The EPA confirms that indoor air is usually more polluted than outdoor air.

The rocker in the nursery contained seven times California's recommended level of formaldehyde, a chemical known to cause cancer. The crib mattress gave off more than 100 different chemicals, including industrial solvents and alcohols.  Meanwhile, the paint used on the nursery's walls contained chemical gases at five times the recommended limit.

Yet, none of the products used in the "GMA" testing were in violation of any law. Fortunately for consumers, there are easy, practical steps you can take today to minimize you and your family's exposure to your home's chemicals.

Look for certifications.  Certifications for low chemical emissions are in their infancy, but the more people who buy and request certified products, the more there will be.  Greenguard, part of Underwriters Laboratories, certifies furniture, paint, and other office and household products.  Scientific Certification Systems is another certifier.  And, for carpet, you can look for the "Green Label Plus" created by the Carpet and Rug Institute (CRI).

Choose unscented products.  Many manufacturers make both scented and unscented versions of their products.  Always choose the unscented ones.

Avoid pressed wood.  Pressed wood and wood composite materials are manufactured using strong glues that often contain volatile organic compounds.

Unwrap.  When you buy new furniture, unpackage it outdoors and let it sit outside for at least one week to air out. Similarly, make sure to unwrap your dry-cleaning outdoors before bringing it into your house.

Ventilate.  Try to paint in the spring and fall when you can comfortably leave your windows open for ventilation.  Same goes for new furniture or cabinetry.  Keep your windows open for a couple of weeks, if possible.

Paint first.  It's a good idea to paint your home first, then ventilate for several days before installing new carpeting and other textiles.  That's because these products can absorb chemicals from the paint and re-release them into the air over time.

Buy used.  Chemical emissions are at their highest when a product is brand new, so one solution is to buy used furniture that has already off-gassed in somebody else's house.  (Unless that used furniture has just been refinished.)  Just be careful, because you want the latest safety features in things like baby cribs.  And you should look for furniture built after 1978, when lead paint was banned