In the 1980s, the use of asbestos in house siding materials underwent a significant decline, ultimately being phased out by the mid-1980s to early 1990s. This change was largely due to a growing awareness of the severe health risks associated with asbestos exposure, particularly its link to lung diseases and cancers. With increased public concern and regulatory agency involvement, building codes and regulations were updated to restrict the use of asbestos in construction materials. 

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.

In the event of suspected or confirmed asbestos contamination on the body, it is imperative to take immediate measures to reduce health risks. To avoid further exposure, carefully remove contaminated clothing and shower thoroughly to remove any asbestos fibers. Seek prompt medical attention, and inform your healthcare professional about your suspected asbestos exposure. Since asbestos-related health issues can take years to surface, regular medical check-ups are advised for anyone with a history of exposure.

Even a single, one-time exposure to asbestos can be harmful and pose health risks. According to the EPA, any contact can increase the risk of developing asbestos-related diseases and certain types of cancer, although the likelihood of severe health issues increases with repeated or prolonged exposure.

The severity of a single exposure depends on factors like the duration, intensity, and concentration of the asbestos fibers. While a small amount is less likely to cause significant damage, a high concentration can lead to serious long-term lung damage. Individual reactions vary, and asbestos-related illnesses may not appear for 10 to 40 years after inhalation.

Given these risks, always take precautions around any material suspected to contain asbestos. Personal protective equipment (PPE) may not be completely effective. If you suspect asbestos is in your home, hire a professional for testing and removal. If you are worried about a potential exposure, consult your doctor.