THE RELATION BETWEEN SUBJECTIVE DUST EXPOSURE ESTIMATES AND QUANTITATIVE DUST EXPOSURE MEASUREMENTS IN CALIFORNIA AGRICULTURE

Measuring exposure levels for epidemiologic research is time consuming and expensive and therefore subjective exposure estimates are sometim es used instead In this study we related the subjective dust exposure estimates of workers in California agriculture to personal dust exposu re measurements. One hundred and twenty-four observations were availab le for comparison of subjective dust estimates and inhalable dust meas urements and 129 observations for comparison of subjective dust estima tes and respirable dust measurements. Individual subjective dust estim ates showed weak to moderate correlations with measured dust concentra tions for both the inhalable (R-s = 0.67) and respirable dust fraction (R-s = 0.36). The within-worker reliability coefficients were low (0. 2 and 0.1, respectively). Grouped subjective dust estimates performed better and showed a consistent increase with average measured dust lev els, in particular for the inhalable dust fraction (R-2 = 0.81). Age, the number of years working in agriculture, education level, the prese nce of any respiratory symptoms, and the language of the questionnaire did not have a significant independent effect on the relationship bet ween measured dust levels and subjective dust estimates. California ag ricultural workers appear to be reasonably good at estimating inhalabl e dust levels, in particular if an average of many different workers i s taken, but they are unable to provide good estimates of respirable d ust levels. Measuring dust levels remains the preferred option. (C) 19 97 Wiley-Liss, Inc.