Calibration of a Continuous-Reading Aerosol Monitor (Miniram) to Measure Borate Dust Exposures

Abstract

In conjunction with an epidemiologic study of the acute respiratory effects of sodium borate dust, an intensive exposure assessment effort was carried out. Continuous real-time monitoring of personal total dust exposures was needed to examine the relationship of short-term dust exposures to acute upper respiratory irritant responses. The Miniram is a personal continuous-reading aerosol monitor that was designed as a respirable dust monitor. To use it as a total dust sampler, it was necessary to develop calibration curves for each of the sodium borate dust types. To this end, more than 450 area samples were taken representing a range of concentrations and sodium borate dust types, using the Miniram with an in-line filter. Most of the resulting calibration curves suggested little or no effect of concentration, except at very low concentrations where the particle sizes are smaller and more significantly affect the relationship of the Miniram to the gravimetric concentration. The dusts measured had particle size distributions with large mass median diameters (MMDs) so that most of the particle mass fell outside the American Conference of Governmental and Industrial Hygienists “respirable” range for which the Miniram is most sensitive. Nevertheless, the Miniram was able to produce calibration curves with high R² (> 0.80), suggesting that it works adequately as a total dust monitor for dusts of large MMDs. Woskie, S.R.; Shen, P.; Finkel, M.; Eisen, E.A.; Smith, T.J.; Smith, R.; Wegman, D.H.: Calibration of a Continuous-Reading Aerosol Monitor (Miniram) To Measure Borate Dust Exposures. Appl. Occup. Environ. Hyg. 8(1):38-45; 1993.