Carpeting is a home for animal dander, mold, dust mites and numerous mites and microorganisms. As human and pet dander, food and other organic products fall onto rugs, they will dissolve into fine dust and penetrate deep into the bottom of the carpet. There these particles become a food supply for dust mites. Carpeting itself can be a source of allergens. For example, wool carpets break down over time, releasing wool antigen into the air. Carpeting can also be a source of outgassing, creating fumes that irritate your allergies. Remember to fresh air ventilate areas with new carpets.