Summary: The Mine Safety and Health Administration (MSHA) became aware of the need for tamper-resistant cassettes in its respirable coal dust control program in 1975 after coal mine operators tampered with required coal dust samples collected in their mines. The Bureau of Mines awarded a contract to develop a tamper-resistant cassette, but prototype testing in 1978 revealed problems, and the government's interest in producing such a device waned. A cassette manufacturer privately developed a tamper-resistant cassette in 1991, and the Labor Department began requiring coal mine operators to use the new devices in 1992. MSHA considered tamper-resistant pumps for its program in the 1970s but never received enough funding to pursue development. In 1992, the same manufacturer that modified the cassette also produced a tamper-resistant pump that MSHA bought for its inspectors to use when taking coal dust samples. MSHA began using the pumps in January 1993 but does not plan to require coal mine operators to buy and use them immediately. According to MSHA, the mine operators will buy the improved pumps as they replace those now in use because only the tamper-resistant pumps are now being produced. Over the years, research has been done on alternative monitoring devices to improve the collection and measurement of respirable coal dust samples--mainly fixed-site, continuous monitoring systems. So far, however, these efforts have been unsuccessful, and MSHA officials believe that such technology is years away.
