LAUSR

More than two decades ago it was shown that temporal variability in exposure concentrations outweighed personal variability in exposure concentrations among workers performing similar jobs at the same location. Temporal variability appeared distinctly influenced by environmental and production factors. The IMA Europe Dust Monitoring Programme database contains more than 40.000 personal measurements of respirable dust and quartz and allows estimation of temporal and personal variability over 17-years. We compared variability of respirable dust and quartz concentrations and studied differences across jobs. In addition we correlated trends in exposure variability with temporal trends in median exposure concentrations. As expected temporal variability was considerably higher than variability in average personal exposures. Median fold-range in exposure concentrations from day-to-day amounted to a factor 10 for respirable dust and were almost twice as high for respirable quartz. Remarkably, median fold-ranges of differences between workers performing similar jobs at the same location were small (factor 1.3 and 1.8 respectively for respirable dust and quartz) and hardly changed over time. In contrast temporal variability did change considerably and followed temporal trends in median concentrations. We hypothesize that exposure to respirable quartz is harder to control than exposure to respirable dust. This could be due to quartz being present in smaller dust fractions which ae more difficult to contain. In addition, changes in task content and efficiency of control measures will result in less or more temporal variability, consequently leading to down- or upward trends in exposure levels. Increasing (temporal) variability in exposure concentrations should immediately trigger exposure control.