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 own a stereo microscope, you should be able to see the fibers. The stereo microscope often can perform magnification up to 50x. But unless you have experience viewing asbestos fibers, you may not know exactly what you are seeing. Some fibers are curly, while others are long and straight. Blue, brown, white, and gray colored fibers are all possible.

Epoxying over asbestos tiles is generally considered a safe option when done correctly. Epoxy acts as a sealant, encapsulating the asbestos tiles and preventing the release of asbestos fibers into the air. The key is ensuring that the asbestos tiles are in good condition, firmly adhered to the substrate, and not damaged or deteriorating. This method is only appropriate for tiles that are undamaged and securely in place. If the asbestos tiles are already loose, damaged, or deteriorating, encapsulating them with epoxy may not be a sufficient solution, as it might not address the potential for ongoing asbestos exposure.

No, you do not have to worry about new popcorn ceilings having asbestos. All residential building materials used since the mid-1980s stopped including asbestos, so new popcorn ceilings have no risk of asbestos. You can still create a textured drywall ceiling with a popcorn texture if you like, but new techniques have no risk of adding asbestos.