Environmental influences on respirable dust production from agricultural operations in California

Abstract

Agricultural operations may contribute to the respirable dust (RD) that affects the air quality of California's Central Valley. In order to minimize RD production, it is necessary to understand the role of two of the more important variables that influence RD production, soil water content and air temperature. Personal cyclone samplers were mounted on agricultural implements used in farming operations over two years to capture ⩽4 μm aerodynamic-diameter RD particles. For cultivation operations under widely different environmental conditions, RD concentration decreased as a power function as soil water content increased between 2 and 14% and increased linearly as air temperature increased. Similar results were found for an experiment with a land plane when samples were collected at 126, 156, 186, 216, 246, and 276 cm above the soil surface with either soil water content or air temperature held constant. For some cultivation operations, RD increased as a power function of air temperature between 7 and 24°C. For a loam surface horizon at one sample site, RD concentration increased 2–5 times at 34°C compared to 18.6°C.