78 Application of End-of-Shift Respirable Crystalline Silica Monitoring to Construction

Abstract

Abstract Pilot project was conducted to determine the effect of common construction dusts as interferences in a new portable end-of-shift (EoS), direct-on-filter (DoF) sampling and analysis method for respirable crystalline silica (RCS), in this case quartz. The sampling and analysis system was developed by NIOSH (USA) for mineral dusts containing quartz in the mining environment. Construction dusts were prepared from plaster, drywall, cement and brick by grinding bulk materials to dust, aerosolizing the dust, and collecting the respirable fraction with high flow-rate respirable cyclones. Laboratory samples were generated by loading filters with different levels of Min-u-Sil 5 α-quartz, and different levels of the interfering dusts, singly and in combination. Samples were analyzed by the EoS-DoF FTIR procedure and some samples were sent for confirmatory XRD analysis. Good correlations were found between nominal quartz loading (0 µg, 25 µg, 50 µg, and 100 µg) adjusted for quartz in the interfering dust and FTIR absorbance alone and in the presence of all interfering dusts. In the important range of adjusted nominal quartz values (25-110 µg) the slopes of the correlations are similar. The presence of cement leads to lower quartz values and brick leads to higher values, but overall, 92% of the quartz contents predicted from the averaged calibration data agreed within 50% of the adjusted nominal loadings. This result is encouraging given the high levels of interfering dusts. Samples loaded with smaller amounts of all four dusts in combination gave even better results, with all nine results within 25% of the adjusted nominal loadings.