Radon is a gas that occurs naturally in the earth’s crust. It is invisible, it is odourless, and it is tasteless. Radon is a product of the decay of uranium. When uranium decays, it turns into lead. This is a 14-step process; radon is formed at the sixth step.
Lead is a naturally occurring element in soil and is also collected from the air and other sources.
Carbon monoxide is a colourless, odorless gas. It is a by-product of incomplete combustion, such as natural gas, liquid fuels, and anything that burns.
Asbestos is a fibrous material that was used in many building materials as acoustic insulation, a fire-resistant material, a binder in other products such as roofing material, and was also used as thermal insulation.