Successful experiences with a handy equipment to measure dust concentrations in various workplaces.

Performance of a direct-reading handy equipment for dust counting in workroom air, PDR (MIE, USA), was field-tested in comparison with the results of low-volume air sampling-gravimetry. Application in 64 workplaces of various type dust work with dust concentrations of up to 1.6 mg/m3 showed that the agreement was generally good with a correlation coefficient (r) >0.64. The calculated regression line had a slope close to one, and the intercept on the axis was next to nil, suggesting that the measurement with PDR is essentially the same with that by low-volume air sampling. Further analysis by types of dust work disclosed that the correlation was best when examined in 12 foundries with r as large as 0.95. In contrast, r was small (0.52) in 11 welding workplaces, possibly due to smaller particle size of dust generated during welding.