When purchasing an older house, potential buyers may ask themselves certain questions: Can the plumbing meet the demands of a modern family? Does the power grid need to be updated? Are there any contaminants in the home that may pose a health hazard – mold, lead paint, asbestos?

If asbestos exposure is a prominent concern, potential home buyers should be mindful of the type of insulation that lines the walls and attic of a house. During the 20th century, asbestos was a common component of insulation materials because of its ability to withstand heat, as well as its fireproofing abilities.

One example of insulation that may contain asbestos is vermiculite. Considering that more than two-thirds of the vermiculite in the U.S. came from the Montana town of Libby, and that the source was contaminated by asbestos, home owners should be alert to the presence of these minerals around the house.

A town history marred by asbestos
Between the 1920s and 1990s, Libby was known for being the nation’s main source of asbestos. Public health experts estimate that 70 percent of vermiculite in the U.S., as well as 80 percent of the world’s supply, came from this mining town. One reason why vermiculite was popular was due to its propensity of mineral flakes to expand eight to 30 times their original size when exposed to high temperatures.

Libby’s asbestos was distributed to more than 250 regional processing plants and ultimately shipped to every state in the U.S. Much of this product was processed and sold under brand names such as Zonolite insulation and Monokote fireproofing. Additionally, some manufacturing plants gave the waste product away for free to the local residents, who may have used it as filler material for the driveways and gardens.

However, the presence of amphibole asbestos in the vermiculite mine meant that as much as 26 percent of the raw ore contained asbestos. During the 1980s, public health experts started paying more attention to the well-being of Libby’s residents, who were experiencing higher rates of diseases related to asbestos exposure, such as malignant mesothelioma. These illnesses were affecting not just the miners, but also members of the miners’ households and other residents not connected to the industry.

In 2002, about a decade after the mine closed, the federal government designated Libby as a cleanup site.

Vermiculite around the house
If vermiculite is present in your home, it is likely located in the attic, inside the walls or around the yard. If you find vermiculite, you should assume that it came from Libby. The first step to protecting yourself is to refrain from handling the material. Disturbing it may cause asbestos fibers to become airborne.

When asbestos is in the attic, it is best to not use it for storage. However, you must enter the attic, try to limit the number of trips you make. If there are children in the house, do not allow them to play in the attic. Should you decide to make any renovations that involve the attic or walls that contain vermiculite, be sure you hire someone who is knowledgeable about the risks of asbestos exposure.

If you would rather not have the vermiculite in the house at all, do not try to remove it yourself. Instead, hire a professional contractor who is specially trained to handle such hazardous materials.

Remember that there is no known safe level of asbestos exposure. If you are worried about whether came into contact with the hazardous mineral, consult a doctor or pulmonary specialist.