Kelly, I'm not an alarmist kind of guy, but have you ever seen a microscopic picture of old wall to wall carpeting? If it's not routinely cleaned, and honestly, even if it is, it's absolutely disgusting. A sea of bacteria, molds, pet dander, dust, dust mites and their droppings, a long list of other nasties and critters that feed on it.
Credible studies have shown up to 200x as much air contamination (mostly dust mites and their droppings) in homes with wall to wall carpeting compared to homes with hard floors. If you're dealing with any kind of chronic illness, especially related to lungs, allergies or ENT, do yourself a favor and rip that carpeting out of your house, or at least use air filtration in rooms where you spend the most time (usually bedrooms and living rooms).