No, not all popcorn ceilings have asbestos, but a vast majority do. The Environmental Protection Agency (EPA) banned its use in 1973, although it still may have been used up through the early ‘90s. But, in general, homes built or remodeled before the early ‘80s likely utilized materials with asbestos. That being said, a professional test is the only way to determine for sure.

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.

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.

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.