AN EVALUATION OF KONIMETER PERFORMANCE—II. A FIELD COMPARISON OF KONIMETERS

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Abstract
Two konimeters, the Devers and the Witwatersrand, with and without a size selecting pre-impactor, were compared with a Gathercole konimeter as part of a large epidemiological study. Simultaneous samples were taken in both a gold mine and a uranium mine. Dust counting was done with an automatic particle scanner at the Mines Accident Prevention Association of Ontario. A comparison of two Gathercole konimeters in both the uranium and the gold mine showed that like instruments give identical measurements of particles per cubic centimetre (ppcc). In the uranium mine, the Witwatersrand konimeter gave a 25% lower measurement of dust concentration than the Gathercole. The pre-impactor reduced the particle concentration measurement of the Witwatersrand konimeter by about 4%, but the result was not statistically significant. The Devers and Gathercole konimeters gave similar measurements. In the gold mine, both Devers and Witwatersrand measured dust concentration identically to the Gathercole. However, the Witwatersrand (with pre-impactor) measured 18% higher ( P <0.01) than the Gathercole. The difference in konimeter comparisons between the two mines may be caused by a difference in the size distribution of the airborne dust, which in turn is dependent on the mineral composition of the mine. This would vary between ore types and possibly between mines of the same ore type. The measurements of dust concentration obtained by the Witwatersrand (with pre-impactor) may be influenced by the amount and subsequent disintegration of aggregates in the airborne dust.