Vermiculite insulation still in the original bag in this attic ceiling may contain asbestos fibers. Zonolite Vermiculite ZAI Insulation & Asbestos Hazards
Zonolite identification photos, hazards, history, advice

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Zonolilte ZAI Vermiculite Insulation Information:

What is Zonolite™ vermiculite insulation, how is it identified, & what should be done about potential vermiculite-asbestos hazards ascribed to Zonolite ZAI attic insulation? Zonolite or ZAI (zonolite attic insulation) hazards, settlement, claims website contact information & advice on what to do about this material in buildings.

This article series explains how to recognize vermiculite building insulation that may contain asbestos fibers and what to do about it. We provide photographs and descriptive text of asbestos insulation and other asbestos-containing products to permit identification of definite, probable, or possible asbestos materials in buildings.

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Zonolite Brand Vermiculite Insulation, ZAI (Zonolite Attic Insulation) Dust & Tremolite Asbestos Hazards

Vermiculite insulatin bags in an attic (C) D Friedman D GrudzinskiWatch out: Depending on the mine from which this mineral-based insulation was obtained, vermiculite insulation may contain asbestos fibers (including tremolite asbestos) and could present a hazard in buildings, especially if disturbed during renovations. Zonolite™ brand insulation or ZAI contains amphibole asbestos and may be hazardous if disturbed.

Article Contents

The U.S. EPA has photos of the original bags [PDF] in which this product was shipped - you're not likely to see these bags in a home, though I've found them on occasion as you'll see in our own photograph of a Zonolite Insulation Fill bag shown at above left. - original source

Vermiculite insulation has an R-value of about 2.13 per inch in buildings.

As we discuss at our notes on other loose-fill insulations such as mineral wool or cellulose, any building insulated with loose-fill or spray-in insulation may benefit from the ability of these loose materials to fill gaps and openings more uniformly than might be found if sloppy workers are careless about installing insulating batts.

Drafty insulation installations can cause more heat loss than is made up for by differences in insulation R-values.

Zonolite Vermiculite Building Insulation History & the Libby Montana Vermiculite Mine

According to a helpful timeline published by Grace [11], commercial mining of vermiculite began in Libby Montana in 1923, ten years after Vermiculite Mountain was discovered in that town. Twenty one years later, in 1944, a question of possible hazards due to dust levels in the Libby vermiculite production plant was addressed by the Montana Department of Health who found dust levels below 50 ppm/ft3 and concluded that the dust was a nuisance but not hazardous.

By 1950, six years later, vermiculite production under the Zonolite brand reached 150,000 tons per year, and in 1954, as a measure to reduce dust levels in the mill, the first wet mill was installed at the Libby mine.

Asbestos in the Libby Montana Vermiculite Product

Photograph of - tremolite asbestos, asbestiform tremolite, collected from asbestos slab ceiling insulation

In 1956 the US Department of Health estimated that vermiculite mined from the Libby site had an asbestos content of 10% but added that there was no reliable way of analyzing asbestos content.

Walter C. McCrone, at McCrone Research Institute published detailed procedures for identifying asbestos by microscopic examination, and identifying which type of asbestos is in a material.

But that work was not published until 1980 in McCrone's "Asbestos Particle Atlas", and again in 1987 in detailed procedures described in his book, Asbestos Identification.[13]


In 1956 the USDOH recommended a 50 mppcf limit of total dust and according to Grace, added "If the company will cooperate and actually attain dust control of this order, the asbestos and silicosis hazard would certainly be minimal." [11] suggesting that the health risks such as mesothelioma from asbestos dust exposure were still poorly understood.

Tremolite asbestos, the principal form of asbestos found in vermiculite from the Libby Montana mine, was identified by the Montana State Board of Health in 1961.

W.R. Grace Purchase of the Libby Montana Zonolite Corporation & Vermiculite Mining Operation

Up until the 1963 purchase of the Libby Montana vermiculite mine and the Zonolite corporation by W.R. Grace corporation, vermiculite insulation product mined at Libby was under the auspices of the Zonolite corporation. Grace indicates that at the time of the purchase, the company was unaware of the lurking asbestos hazards associated with mining and milling vermiculite. [11]

However by the following year it is evident that the new Libby Montana vermiculite mining operation had become aware of the health concerns associated with dust at the mining facility, because in 1964 the company initiated an annual x-ray testing program for Libby workers, and in the following year the company began moving employees reporting breathing concerns to less dusty areas of the facility.

Just one year later, in 1966 the Montana Board of Health reported dust concentrations at the Libby Montana vermiculite facility as varying between 9 ppm per cubic foot of air and 52 mppcf, complimenting Graces's efforts to reduce dust levels but indicating that further measures were needed. And in the following year, 1967, the Libby Montana mineworkers' union filed the first asbestos-related health claim. At that time even the union reported that dust levels had been reduced and that most (96%) of the dust level measurements were within Montana's "safe" threshold of 50 ppm per cubic foot or less.

The Libby vermiculite mining operation between 1967 and 1978 includes additional steps by the company to reduce dust exposure for workers. Most likely because it was apparent that there was a connection between airborne asbestos exposure health risks and smoking (tar in the lungs keeps particles therein), led Grace to ban smoking on premises in 1978, prompting a union grievance. And in 1983 Grace, complying with the Toxic Substances Control Act, filed notice of possible health effects from exposure to tremolite asbestos at the mining facility. The company consulted NIOSH, and McGill University began a health study of this topic in that same year. Findings of the McGill study, indicating that the levels of tremolite asbestos were one twentieth the standard set by federal regulations were reported to employees two years later in 1985.

Closure of the Libby Montana Vermiculite Mine in 1990, Grace Bankruptcy Filings

The LIbby Montana vermiculite mine was closed by W.R. Grace corporation in 1990. In that year the company also closed all of its (more than 20) vermiculite insulation processing plants located throughout the U.S.

On 2 April 2001 the corporation filed for bankruptcy under Chapter 11 reorganization procedures in response to an 81% increase in asbestos claims in the preceding year and an increasing claims rate in 2001. According to the company, these asbestos liabilities stemmed from commercially-purchased chrysotile asbestos that Grace added to some of its fire protection products [not the tremolite asbestos found in Zonolite vermiculite building insulation-Ed]. The initial bankruptcy filing was amended on 13 January 2005, and disagreements between the company's creditors and stockholders and asbestosis property damage claimants continued along with further amendments to a final resolution on 31 January 2011.and all objections were closed on 31 January 2012.[15] The corporation describes the final resolution as follows:

The Joint Plan establishes two asbestos trusts to compensate personal injury claimants and property owners. Funds for the trusts will come from a variety of sources including cash, warrants to purchase Grace common stock, deferred payment obligations, insurance proceeds and payments from successor companies. The trusts’ assets and operations are designed to cover all current and future asbestos claims. [15]

W.R. Grace Position Statement on Zonolite Insulation

Zonolite® Attic Insulation was primarily used in older homes to retrofit or add to existing insulation. It was seldom used in new home construction. We believe now, as we did during the time we sold the product, that there is no unreasonable risk of injury or illness associated with the presence of this insulation in homes. Homeowners who have Zonolite® Attic Insulation in their homes should leave it in place. Homeowners who have questions about the product can contact Grace at 617-876-1400 (in Massachusetts) or 800-354-5414 (elsewhere in the U.S.). For more information, please visit the web site
[website name deleted as it was found not functional on 5/1/12-Ed]. [10]

"ZAI" & the Zonolite Attic Insulation Trust Claims Information

Zonolite Attic Insulation (ZAI) Asbestos Abatement Expense Claims

2008 Status: The United States Bankruptcy Court for the District of Delaware set 31 October 2008 as the bar date for Zonolite Attic Insulation (also branded "ZAI") claims to be filed in the W.R. Grace Personal Bankruptcy Case. The claims that were allowed prior to the bar date above included the cost of the abatement or removal of asbestos containing insulation and may have included a claim for other financial losses such as a reduction in property value where this insulation material was installed.

2014 Update: The W.R. Grace company's reorganization plan has funded a trust that will make limited payments to homeowners or tenants in structures in the United States that contained Zonolite attic insulation ("ZAI"). Claimants are required to show that ZAI is or was installed in the structure and must document their expenditures to "remove, abate, or contain" the Zonolite insulation as well as proof of ownership or tenancy in the structure.

W.R. Grace's plan of reorganization became final on February 3, 2014. Consequently, W.R. Grace has now funded the Zonolite Attic Insulation Trust from which eligible Claimants will be reimbursed for their legitimate ZAI Property Damage Claims ("ZAI PD"). Under the settlement, Grace will fund an independent Trust and Claims Facility ("the Trust") that will operate for a minimum of 20 years educating the public about the potential health effects associated with asbestos containing vermiculite/ZAI.

...The Trust may provide a reimbursement contribution of 55% of the abatement cost for eligible Claimants up to a ceiling of 55% of a $7,500 removal bill (or $4,125) - source, retrieved 24 March 2015

Zonolite Attic Insulation Claims Information

ZAI claim instructions indicate that claimants can choose one from among seven [in our opinion generous] choices given to demonstrate that vermiculite insulation was installed in their building: [Note that the following are adapted & paraphrased. Readers should be sure to see the actual ZAI claims instructions and forms at the Zonolite Attic Insulation Trust website or at additional links given below].

  1. A physical 3-oz sample of Zonolite Attic Insulation including a signed statement indicating the sample source
  2. A laboratory report showing the presence of vermiculite in a sample from the structure.
  3. The original Zonolite Insulation Bag or portion of a bag or a photograph of a ZAI bag in the structure along with a statement indicating the sample source
  4. Photographs of the insulation material before and after cleanup along with a statement indicating the sample source
  5. Statement from a certified asbestos abatement contractor indicating that the ZAI was present
  6. A receipt or invoice for the purchase of Zonolite Attic Insulation
  7. For claims filed on or before 10/31/2008, a declaration that ZAI was installed in the structure and that the signing claimant has direct personal knowledge of it.

Note: "The product identification requirements depend upon whether the ZAI was removed before or after 6/16/2014 (the date the ZAI Trust became operational). Refer to the column on the claim form that fits your situation." - source: retrieved 24 March 2105

ZAI Trustee comment: the U.S. Zonolite Attic Insulation Trust is Now in Operation

24 March 215 ZAI Trustee said:

The U.S. Zonolite Attic Insulation Trust is now in operation. It actually operates differently than indicated above. The "bar date" does not apply and the recoverable damages have certain limitations that were not noted. Please
see Zonolite Attic Insulation Trust
at [note: the link provided by the trustee auto-forwards to - Editor]

see to get the information or to file a claim.

Excerpts from the above website:

We are pleased to advise you that W.R. Grace's Plan of Reorganization became final on February 3, 2014. Consequently, W.R. Grace has now funded the Zonolite Attic Insulation Trust from which eligible ZAI claimants will be reimbursed. This web page contains all the information you need to submit a claim for reimbursement.

The information and procedures contained herein are subject to modification and/or retroactive application as circumstances and/or the needs of the Trust may require.

How to Contact WR Grace & Zonolite Asbestos Claims Trusts

Asbestos personal injury claims related to WR Grace

WRG Asbestos PI Trust

For Zonolite Attic Insulation claims:

Zonolite Attic Insulation Trust

Asbestos property damage claims other than for Zonolite Attic Insulation:

Richard B. Schiro, Trustee
Law Offices of Richard B. Schiro
2706 Fairmount Street
Dallas, Texas 75201-1958

- Source:

What to Do About Your Vermiculite Insulation

The best way to minimize your risk of amphibole asbestos exposure is to avoid disturbing vermiculite-based insulation in any way. If vermiculite-based insulation is contained and not exposed to the home or interior environment, it poses very little risk. - Health Canada


Article Series Contents


Continue reading at WHAT TO DO ABOUT VERMICULITE INSULATION or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

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