1913 Vermiculite Mountain in Libby, Montana discovered. 1923 Commercial mining begins at Libby. 1944 Montana State Board of Health defines dust at the Libby plant as "nuisance dust." Measurements are well below 50 mppcf (million particles per cubic foot) for total dust, indicating "no dust hazard." 1950 Zonolite production reaches 150,000 tons per year. 1954 First "wet" mill is installed at Libby mine. 1956 U.S. Department of Health scientist informs Montana Health Department there is no reliable way of analyzing asbestos content, estimating 10% of Libby ore is asbestos and recommending a 50 mppcf limit of total dust. He adds, "If the company will cooperate and actually attain dust control of this order, the asbestos and silicosis hazard would certainly be minimal." 1959 Zonolite requests chest x-rays of all Libby employees. Of 130 mine employees, 48 show abnormalities. Results are sent to each employee’s family physician. 1961 Montana State Board of Health survey shows extremely high and substantial concentrations of asbestos dust in the first report to identify tremolite asbestos at the Libby mine. 1963 Grace, unaware of the extent of hazards of mining and milling vermiculite, purchases Zonolite Co. 1964 Grace initiates annual x-ray testing of Libby employees, reporting results to each employee’s family physician. 1965 Grace begins moving employees with breathing concerns to less dusty areas of the plants. Dismayed by former mine owner Zonolite's slowness to react to State Board of Health recommendations, Grace explores "wet" mill technology to reduce dust. 1966 Montana Board of Health reports total dust concentrations at Libby plant between 8.0 and 52 mppcf, noting, "Some good work has been made and housekeeping has substantially improved over previous times. But, other engineering changes need to be implemented to further reduce dust." Grace responds with plans to further reduce dust through purchase of high-load fans, application of oil on mine roads and research to develop wet mill technology. Grace installs 50-foot stack, plus additional exhaust fans and cyclones to further reduce dust. 1967 Libby mineworkers' union files first asbestosis claim. State Board of Health reports, "Our view of the operation of the plant and the dust samples taken in the dry mill during these two periods indicated that, in general, the dustiness in the dry mill had been reduced substantially from previous periods and the systematic review of the dust concentration showed a reduction over previous periods." While 96% of all dust counts are within the State's imposed "safe" threshold--not requiring a respirator--Grace still requires respirator use in most locations throughout the mill. 1968 Grace installs stronger filters in cyclones to further reduce dust. 1969 Engineering work gets underway for construction of new wet mill to significantly reduce dust. Grace commences air sampling and initiates dust control measures, such as bag houses, enclosed silos, improvements in furnace and ventilation systems and improved work practices at its vermiculite expanding plants. 1970 U.S. Bureau of Mines reports "Work on alleviating dust conditions proceeding," when Grace installs air-filtered hoods for tractor loader, air filter systems on trucks, cabs and skipper's shack and new respirator sterilization center. Wet mill construction begins. 1971 Grace initiates annual x-ray testing in all vermiculite expanding plants. 1972 Grace begins wet mill construction in Libby at a cost of $14 million. Grace initiates membrane filter air-sampling program at Libby. 1974 New wet mill becomes operational, significantly reducing airborne mill asbestos dust to levels considered safe by government agencies--several thousand times lower than when Grace purchased the mine from Zonolite in 1963. Grace implements lung function tests for Libby employees. 1976 Grace continues improvements in ventilation system and work practices to reduce fiber exposures at plant. Grace implements intensified air-sampling program. 1977 Grace no longer hires smokers. 1978 Grace implements employee health questionnaire. Grace bans smoking on premises, prompting mine workers’ union to file a grievance, despite Company educational program citing substantial health risk to smokers exposed to asbestos dust. 1983 Grace files notice under Section 8(e) of the Toxic Substances Control Act, reporting possible health effects from exposure to tremolite at Libby. Grace visits NIOSH to discuss health studies by McGill University. McGill begins health studies for Grace. 1985 McGill presents study findings to current and former employee participants, reporting levels of tremolite fiber exposure at Libby are 20 times lower than federal regulations require. Grace requires employees to wear removable coveralls to prevent dust traveling with workers. 1990 Grace closes Libby mine and mill. Land reclamation work begins. 2000 Grace initiates sweeping three-part medical program to provide immediate medical coverage to any and all Libby residents diagnosed with asbestos-related illness. Plan includes annual donation of $250,000 to St. Johns Lutheran Hospital for independent testing, plus additional sums for purchase of state-of-the-art equipment, staffing and technology.