Old carpets can pose a number of health risks, particularly if they haven't been cleaned or replaced in a long time. Dust, dirt, pet dander, and other allergens can accumulate in carpet fibers over time, which can trigger allergic reactions in some people. Additionally, old carpets can harbor bacteria, mold, and other micro-organisms, which can cause respiratory problems and other health issues. Old carpets can also release harmful volatile organic compounds (VOCs) into the air, particularly if they're made from synthetic materials. They can also harbor bacteria and germs that can cause infections and other health issues.