Knob and tube wiring is an older type of electrical wiring that's no longer used and generally not considered safe. However, some homes still have it, or may have a knob and tube wiring system that was incorrectly modified or rigged to work with a modern electrical system. Knob and tube wiring may contain asbestos insulation, but the only way to know is to have the material professionally tested.

If you think you’ve touched asbestos, do not put on a mask. This is important because you may take the asbestos fibers on your hands on trap them in the mask. Make your way to a sink and wash your hands thoroughly. Remove any clothes and seal them in a bag, then take a shower. Call your doctor and let them know you’ve been exposed to asbestos, and make sure you see them as soon as possible. The reason you keep the clothes is in case anyone wants to confirm the presence of asbestos.

Most manufacturers stopped putting asbestos in linoleum before 1980 due to public concerns about its toxicity. However, the Environmental Protection Agency (EPA) didn’t ban asbestos-containing products until 1989, and a comprehensive ban was not announced until 2024. This means that homes built after 1989 may still have asbestos in their flooring.

Asbestos fibers can stay airborne for 48 to 72 hours, depending on the home's ventilation. Fibers can linger longer in enclosed spaces with poor airflow. Because the fibers are microscopic, they can easily remain suspended, making them difficult to detect without professional equipment.