EXPOSURE TO DUST AND ITS PARTICLE-SIZE DISTRIBUTION IN CALIFORNIA AGRICULTURE

The aim of this study was to measure personal dust exposure levels and the dust particle size distribution during various agricultural opera tions in California. Personal dust exposure levels were measured with four-stage cascade impactors and respirable dust cyclones during field crop, fruit and nut farming, and dairy operations at three;aims. Alto gether, 103 cascade impactor measurements and 108 cyclone measurements were ia ken. High personal dust exposure levels were measured during various operations, in particular during ground preparation operations such as land planing (geometric mean [GM] = 57.3 mg/m(3), geometric s tandard deviation [GSD] = 2.4) and discing (GM = 98.6 mg/m(3), GSD = 2 .9). Dust particles were relatively large and the great majority belon ged to the extrathoracic fraction. Dust levels were considerably lower when an enclosed cabin was present on the tractor;;or example, during discing, dust exposure levels were reduced more than sixtyfold for th e larger dust particle fraction and more than fourfold for the respira ble dust fraction.