Vermiculite was used in a variety of insulating applications after it was processed, including Zonolite® Attic Insulation, which was discontinued in the early 1980s. Zonolite® Attic Insulation was primarily used in older homes to retrofit or add to existing insulation. It was seldom used in new home construction. As part of the manufacturing process, Grace took steps to remove fibrous tremolite from the vermiculite used in Zonolite® Attic Insulation. Tremolite was separated from the vermiculite ore at the mine. The ore was further processed at the expanding plant to reduce any remaining tremolite to the maximum extent feasible. In the1970s, the U.S. government began regulating the use of products containing intentionally added commercial asbestos such as fireproofing and insulation. As a responsible manufacturer, Grace conducted its activities in compliance with these regulations. In connection with the development of the National Emission Standard for Asbestos, issued in 1973, the association of fibrous tremolite asbestos with vermiculite in the Libby ore was extensively discussed with the EPA staff. In the late 1970s, Grace conducted air-sampling tests of Zonolite® Attic Insulation. Designed to replicate the installation procedure in typical homes, air sampling was conducted prior to, during and after installation. The results: Asbestos fibers in the attic space during installation were at a level well below what was then considered a permissible lifetime occupational exposure. Air sampling indicated no asbestos fibers were detected in the attic within six hours after installation. Based on these results, Grace concluded that no unreasonable risk of injury was posed to a homeowner installer. 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.).