Exposure assessment can be difficult in agriculture due to the varied
operations and the cyclic nature of the work. In previous studies of dust
exposure in vineyards, exposure levels were measured during a few
operations, including harvest, and extrapolated as representative
exposure. This assessment can cause significant error in chronic exposure
estimation, since we have found that harvest tends to yield some of the
highest respirable dust exposure levels. Personal exposures to inhalable
and respirable dusts were measured during a complete cycle of vineyard
operations. At the same time, an operation profile was collected. By
combining operation profile with exposure level, a task-exposure matrix
was produced. This matrix was used to estimate yearly exposure and
identify the determinant factors of dust exposure in vineyards. Inhalable
and respirable dust exposures were found to vary significantly. The
geometric mean exposures were 0.69 mg/m3 with a GSD of 2.72 for inhalable
dust and 0.05 mg/m3 with a GSD of 2.55 respirable dust. Respirable dust
was not significantly associated with inhalable dust (R2 = 0.1976);
therefore one could not proxy the other. Depending on the size of the
dust, higher exposures were observed for different operations. The highest
levels of inhalable dust exposure took place during cluster thinning and
vine training. The highest levels of respirable dust exposure took place
during harvest, leaf thinning, discing and tractor driving. Assuming the
weekly operation profiles represent their working hours, mean weighted
annual exposures indicate that worker^?s are exposed to 0.74 mg/m3 of
inhalable dust and 0.05 mg/m3 of respirable dust. Exposure to inhalable
dust followed the temperature patterns with the summer months producing
more dust exposures than the spring. Respirable dust does not follow this
pattern.
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