Approximately 79 to 80 percent of all the dirt that ends up in your carpet is made up of dry particles and sand. This type of dirt is most often very abrasive and gritty which will wear on a carpet, which can produce a dull appearance on the upper side. If it is not vacuumed up, this loose dirt and soil will work its way down to the bottom of the pile of the carpet. As people walk on the carpet, the sharp edges of the dirt will cut against the fiber of the carpet as people continue to walk on it. If not vacuumed the fibers at the bottom of the pile can be cut, and the carpet begins to wear out, with wear patterns on the carpet.
The rest of the residue in the carpet is in the form of stains that come from grease, cooking, automobile exhausts, and general sludge from shoes. This type of soil/residue is generally of an acidic nature, and that is why most carpet cleaning solutions have a slight alkaline pH to them, which neutralizes the acidic condition and makes it easier to pick up this part of the dirt.
Carpets are great catch-alls for all kinds of materials such as hair, food particles, and other fibers and residue, which makes them breeding grounds for mold, mildew, bacteria, and mites.
Dust mites and bacteria are unseen and can cause or enhance situations like asthma and allergies, if not removed from carpet on a regular basis. So, frequent vacuuming to remove loose materials like dirt, particles, sand, and body parts of bugs and mites, and a steam cleaning at least once every three months or so helps to kill the bacteria and mites. Set up a regular schedule for these tasks and you will have a healthier family and a good looking carpet.