Vermiculite Insulation

What is Vermiculite?

Vermiculite is a silver-gold to gray-brown mineral that is flat and shiny in its natural state. When heated to around 1000 degrees C, it pops (or puffs up) which creates pockets of air. This expanded form, and the fact that vermiculite does not burn, made the material suitable for use as insulation.

Is all vermiculite a health concern?

Vermiculite itself has not been shown to be a health problem. However, some vermiculite insulation contained asbestos fibers, which can cause problems if inhaled. As long as this kind of vermiculite-based insulation remains undisturbed behind intact walls or in attic spaces and does not become airborne, it should not be a concern. The concern for homeowners may come when additional insulation may need to be added or when electrical work must be done, including the simple changing of a fixture if the ceiling is directly below the attic. Many contractors will not enter the attic if known vermiculite is present. Also of concern is the eventual sale of the home with known vermiculite insulation

Of specific concern is Zonolite® Attic Insulation; this insulation was sold in the US and Canada under the name of Zonolite® and was extracted from the Libby Mine in Montana, USA. This mine had a natural deposit of asbestos which resulted in the vermiculite being contaminated with asbestos.

Vermiculite produced by the Libby Mine has not been on the market since 1990. Not all vermiculite sold before 1990 contains asbestos fibers. However, if you believe that your home may contain vermiculite insulation, it is reasonable to assume that it may be contaminated with asbestos

EPA Issues Vermiculite Insulation Warning

WASHINGTON, D.C.—May 27, 2003—After receiving negative press attention for its failure to warn homeowners of the dangers of asbestos–containing vermiculite insulation, the federal government has finally launched a consumer awareness campaign about the material. The new program comes over a year after the Environmental Protection Agency (EPA) halted the release of a similar campaign at the urging of the White House. (See White House Squelched Alert on Asbestos Insulation later in this paper.)

As a first step, the EPA and the Agency for Toxic Substances and Disease Registry (ATSDR) are distributing a pamphlet to the media and hardware stores. It explains how to identify and manage vermiculite, a mineral ore resembling mica that is used in insulation and potting soil. The majority of vermiculite is derived from a mine in Libby, Montana that contains asbestos. By some estimates, up to 35 million homes in the United States may be insulated with asbestos–contaminated Zonolite, which is the brand name for most vermiculite insulation.

Vermiculite attic insulation is a pebble–like, pour–in product that is usually light brown or gold in color. The EPA recommends that consumers assume that any vermiculite insulation contains asbestos and take appropriate precautions. It provides this advice to homeowners:

  • Do not disturb vermiculite attic insulation. Any disturbance has the potential to release asbestos fibers into the air.
  • If you must go into attic space containing vermiculite insulation, make every effort to limit the number, duration, and activity level of those trips. Boxes or other items should not be stored in attics if retrieving them will disturb the insulation.
  • Do not allow children to play in an attic with open areas of vermiculite insulation.
  • Never attempt to remove vermiculite insulation. If removal is necessary, hire professionals trained and certified to safely remove the material.
  • If you plan to remodel or conduct renovations that would disturb the vermiculite, hire professionals trained and certified to handle asbestos to safely remove the material.

Homeowners can learn more about asbestos vermiculite through the EPA Hotline at 1–800–471–7127. The EPA has also issued a preliminary study of homes with asbestos–contaminated vermiculite insulation. The study points out that disturbing the vermiculite through routine repairs or remodeling can cause asbestos fibers to become airborne. The full text of the report is on the EPA web site. See:

(You will need Adobe Acrobat Reader to access it. If you do not already have the software installed on your computer, you may download a free copy.) For the brochure see:

White House Squelched Alert on Asbestos Insulation

WASHINGTON, D.C.—January 10, 2003—The Environmental Protection Agency (EPA) was set to issue a national alert about asbestos in Zonolite insulation, when the White House intervened, according to a recent news story (St. Louis Post–Dispatch, 12/27/2002). Originally slated for last April, the announcement would have been included in a declaration of “public emergency.”

“When the government comes across this kind of information and doesn’t tell people about it, I just think it’s wrong, unconscionable…” former EPA administrator William Ruckelshaus said about the failure to warn homeowners (quoted in the St. Louis Post–Dispatch). “Your first obligation is to tell the people living in these homes of the possible danger.”

The White House Office of Management and Budget was the agency that nixed the emergency declaration. It is headed by John Graham, a man many environmental and health groups consider unfriendly to consumer causes. - top

Millions of U.S. Homes Contain Asbestos–Contaminated Zonolite

Up to 35 million homes in the United States may be insulated with Zonolite. A large portion of the insulation is derived from asbestos–containing vermiculite, a mineral ore resembling mica that was mined in the small town of Libby, Montana. The contaminated vermiculite was shipped throughout the nation.

Although Libby’s asbestos–contaminated vermiculite mine shut down in 1990, its legacy of death and disease remains. Town residents develop asbestos diseases such as asbestosis and mesothelioma at a rate that is 60 times that of other geographic areas (see Health of Residents Compromised). Libby has been declared a Superfund disaster area, in need of federal aid.

The EPA chose to begin the removal of Zonolite insulation from homes in Libby, Montana, at the same time that it agreed not to issue a nationwide warning about Zonolite dangers (see EPA to Remove Zonolite Insulation from Libby). It also pledged to clean up asbestos–containing soil from Libby yards, school grounds and parks (EPA Environmental News, May 9, 2002). - top

How Zonolite Asbestos Becomes a Hazard

Asbestos–containing Zonolite becomes a problem if it is disturbed or in poor repair. For example, if you drill in an attic insulated with Zonolite, or if the insulation becomes deteriorated, there is a high risk that asbestos fibers will become airborne. The homeowner may then breathe in asbestos dust or fibers.

You cannot determine if your home contains asbestos–contaminated Zonolite by a mere visual inspection. Honest home inspections use to test this material. As of May 1st, 2009 the state of Wisconsin states: “all vermiculite is to be considered to contain asbestos. Testing as of this June 2009 writing is no longer valid

Additional information is available at