Human health effects have been linked to airborne concentrations of fine particulate matter. One source of fine particulate matter in the atmosphere is resuspended soil dust from a variety of activities, including agricultural operations. We have established a method to measure the potential of soil to emit fugitive dust in the PM 10 or PM 2.5 size range. The method is repeatable, and provides an index of PM 10 or PM 2.5 dust that is highly correlated to the soil texture. The ratio of the PM 2.5 Index to the PM 10 Index produced by this method is similar to field observations of ambient PM 2.5 and PM 10 concentrations downwind of agricultural operations in the San Joaquin Valley of California. The PM 2.5 or PM 10 Index will be a more useful parameter to estimate the potential of a soil to emit fugitive dust than the currently used dry silt content of soil. Research is currently underway to relate the PM 10 and PM 2.5 Index to measured emission factors, accounting for soil moisture and type of agricultural operation, so that a more reliable predictive equation can be developed for agricultural practices.