Determinants of the accuracy of occupational hygiene expert judgment

An experimental study was performed to determine the applicability and accuracy of occupational hygienist's expert judgment in occupational exposure assessment. The effect of tier 1 model application on improvement of expert judgments were also realized. Hygienists were asked to evaluate inhalation exposure intensity in seven operating units in a tile factory before and after an exposure training session. Participants' judgments were compared to air sampling data in the units; then after relative errors for judgments were calculated. Stepwise regressions were performed to investigate the defining variables. In all situations there were almost a perfect agreement (ICC >0.80) among raters. Correlations between estimated mean exposure and relative percentage error of participants before and after training were significant at 0.01 (correlation coefficients were -0.462 and -0.443, respectively). Results showed that actual concentration and experience resulted in 22.4% prediction variance for expert error as an independent variable. Exposure rating by hygienists was susceptible to error from several sources. Experienced subjects had a better ability to predict the exposures intensity. In lower concentrations, the rating error increased significantly. Leading causes of judgment error should be taken into account in epidemiological studies.