Identification of agricultural tasks important to cumulative exposures to inhalable and respirable dust in California.

Little data exists on the determinants of agricultural dust exposure, particularly in dry climates. Annual exposure indices to inhalable and respirable dust were constructed by exposure estimates for specific tasks, task duration, and task frequency. The estimates of exposure levels were based on actual field measurements and subjective dust exposure ranking. The task duration and frequency data were obtained by questionnaire from 546 farm operators in California. Annual exposure indices were analyzed to determine which tasks were major contributors to chronic dust exposure. The important tasks were identified by comparisons of the cumulative distribution of exposures for all tasks and the cumulative distribution of exposures with one task deleted. Thirteen and 11 tasks were identified to be important to both inhalable and respirable dust exposures, respectively. Tasks identified to be important to agricultural exposure may be ascribed to exposure duration more than to exposure intensity. Information on task-specific exposure is important for developing control strategies in the agricultural workplace.