Believe it or not, carpeting is one of the biggest contributors to indoor air pollution.
One of the commonest health problems in a house is allergies, and carpets are practically a perfect environment for dust mites, molds and mildew.
Not only that, but the modern wall-to wall carpeting in todays houses are made of synthetic fibers dyed and treated with chemicals (fungicides, soil repellants and pesticides, anyone?) and bonded to synthetic backing with chemical glues. All of these materials release hundreds of Volatile Organic Compounds as they age, in a process called outgassing. Volatile Organic Compounds (VOCs) can be mutagens, irritants and carcinogens. Not the ideal thing to have in your home, to say the least.
Carpet also attracts and retains all that you and your family members track in to the house from the ground outside- dirt, lead dust found in flaking house exterior paint, insects, bacteria, lawn and garden chemicals and other unhealthy debris. Not to mention food crumbs, hair and dead skin particles.
Getting a wall-to-wall carpet 100% clean is nearly impossible (ever rented one of those steam-cleaners to clean your carpet and cleaned...