A model was presented for converting historical environmental measurement data in the taconite mining and milling industry into a form consistent with current sampling methods. The impinger method was used for sampling mineral dusts in dusty mines and industries beginning in 1925. The filter respirable mass method replaced the impinger method in the taconite industry in 1974 and 1975. Side by side impinger dust count area samples and filter respirable mass area samples were collected in two taconite facilities, at a coarse crusher, ore tunnels, a primary concentrator, pellet facilities, and in the open pit. The ratio of respirable mass concentrations to impinger dust count concentrations was 0.102mg/m3 to 1 million particles per cubic foot (mppcf), with a standard error of 0.006 and a correlation coefficient of 0.86 (level of significance less than different from zero. Three additional sets of data were obtained without the express purpose of correlating sampling methods, but were taken at the same location and on the same date. For the combined data sets, the mean ratio of filter sample concentrations to impinger concentrations was 0.104, with a correlation coefficient of 0.81 and an intercept not statistically different from zero. This ratio of about 0.1mg/m3 to 1mppcf was consistent with ratios of authors conclude that a consistent ratio exists between impinger particle counts and filter respirable mass concentration for samples collected at the same location, so that the model can be used to predict mean respirable dust concentrations for job classifications or sample locations from average area sample impinger concentrations.