When heated to a high temperature, these flakes can expand as much as 30 times their original size. 

The expanded vermiculite is a light-weight, fire-resistant, and odorless material and has been used in numerous products, including insulation for attics and walls. Sizes of vermiculite products range from very fine particles to large pieces nearly an inch long.

Much of the vermiculite insulation sold up until 1990 came from a mine that also contained asbestos. Countless homes now contain this insulation which can be a health hazard.

Thousands of Americans die each year from asbestos related diseases. Asbestos has been used for years in many building materials and there is no known safe level of asbestos exposure. 

Exposure to asbestos can result in a condition known as asbestosis which is characterized by shortness of breath and cough. It may lead to severe impairment of respiratory functions. Cancer is also a major concern from asbestos exposure, as inhalation exposure can cause lung cancer and mesothelioma, and possibly gastrointestinal cancers in humans. The EPA has classified asbestos as Group A, a known human carcinogen.

Asbestos fibers must be airborne to cause a health risk through inhalation, so the first step is not to disturb any suspect vermiculite insulation.