Unlike some home problems, such as water damage or pest infestations, asbestos can be very difficult to spot. Asbestos is a mineral in the form of microscopic fibers and was previously used in building materials for its bonding and fireproofing abilities. Insulation, roof shingles, ceiling tiles, floor tiles, pipe wrappings, soundproofing materials, and textured paint features like popcorn ceilings are common sources of asbestos, particularly in homes built before 1980.

Age is perhaps the biggest indicator of asbestos, as legislation passed in the 1970s labeled asbestos as dangerous and regulated its use in building materials. Signs of age in the form of wear and tear or material degradation are also indicators that asbestos fibers may be leaking into the air, but ultimately, it’s difficult to detect with the naked eye. If you have reason to suspect asbestos in your home, it’s best to hire a certified asbestos inspector.

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.

While asbestos can’t be directly absorbed through the skin—the fibers are too big—skin contact can still produce symptoms. Contact dermatitis can flare up in sensitive individuals but in most cases, the danger from asbestos comes from inhaling the fibers, or dust, that is produced when asbestos is disturbed. If you touch asbestos by accident, immediately wash yourself and your clothes.

Since the EPA partially banned asbestos in 1989, it is no longer used to manufacture new siding in the United States; production had largely ceased by the early 1980s. Many other countries, such as Canada, Iceland, and Denmark, also have bans on asbestos. However, asbestos siding is still present in many homes built before the late 1980s. The only definitive way to know if your siding contains asbestos is to have it professionally lab-tested.