Answer:
Answer: '1980'
Asbestos is usually found in buildings and structures before 1980
Step-by-step explanation:
Asbestos also refer to six silicate naturally occurring mineral made of long and thin fibrous crystal. Each fiber has fibrils that cannot be seen by the naked eyes. These fibrils can escape out into the space by abrasions. Great heat resistivity is one of the attributes that made asbestos to be used in buildings. But as a result of the adverse health and safety risk it possesses, asbestos became illegal and condemned in 1980.
Asbestos used in ceilings release fiber when drilled while asbestos used as insulators in boilers, furnaces and pipes releases dust when they go off or worsen. Inhalation of these dust and fibers by human can cause adverse health issues like lungs cancer and asbestosis.
The two approved methods used to check for asbestos dust and fibrils are Polarized Light Microscopy and Transmission Electron Miscroscopy.