Exposure levels and determinants of inhalable dust exposure in bakeries.

The study's objectives were to measure full-shift exposure to inhalable dust in bakeries and define the determinants of full-shift exposure. Inhalable dust was measured gravimetrically. Ninety-six bakery workers, employed in seven different bakeries, participated in the study. Two side-by-side full-shift inhalable dust samples were obtained from each study participant on a single occasion. Samples were collected on 18 days selected at random. During the entire sampling period, bakers were observed and information on 14 different tasks was recorded at 15 min intervals. Other production characteristics were also recorded for each sampling day. These task and production variables were used in statistical modelling to identify significant predictors of exposure. The mean full-shift inhalable dust exposure was 8.2 mg/m3 (range: 0.1-110 mg/m3). A regression model explained 79% of the variability in exposure. The model indicated that tasks such as weighing, pouring and operating dough-brakers and reversible sheeters increased the exposure, while packing, catching and decorating decreased the exposure. Bread and bun production lines were associated with increased full-shift inhalable dust exposure, while cake production and substitution of dusting with the use of divider oil were associated with decreased exposure. Production tasks and characteristics are strong predictors of personal full-shift exposures to flour dust among bakers; these can be altered to reduce exposure levels.