Agricultural dust exposure and respiratory symptoms among California farm operators

To study whether dust exposure in California agriculture is a risk factor for respiratory symptoms.

A population-based survey of 1947 California farmers collected respiratory symptoms, occupational and personal exposures. Associations between dust and respiratory symptoms were assessed by logistic regression models.

The prevalence of persistent wheeze was 8.6%, chronic bronchitis 3.8%, chronic cough 4.2%, and asthma 7.8%. Persistent wheeze was independently associated with dust in a dose-response fashion odds ratio, 1.2 (95% confidence interval[CI]=0.8-2.0) and 1.8 (95% CI=1.1-3.2) for low and high time in dust. A borderline significant association between chronic bronchitis and dust exposure was found. Asthma was associated with keeping livestock, but not with dust exposure.

Occupational dust exposure among California farmers, only one third of whom tended animals, was independently associated with chronic respiratory symptoms.