This Bureau of Mines report describes the results of a program to develop small, rugged scrubbers with high dust collection efficiency for use in underground coal mines. Several types of improved scrubbers that are especially suitable for various underground mining applications were developed. Research efforts concentrated on reducing the size, power, and water consumption of these scrubbers, while optimizing their dust collection efficiency. Fractional dust collection efficiency, air volumetric range, size, power, water consumption, and application guidelines for each type are described. The dust collection efficiency of six scrubbers--a venturi, two flooded-fibrous-bed, a venturi-impaction plate, a wetted-fan, and a rotating flooded-bed--were compared. The rotating flooded-fibrous-bed and the stationary flooded-fibrous-bed scrubbers showed the highest coal dust collection efficiency. Test results show that these scrubbers can generally achieve respirable size coal dust collection efficiencies in the high 90-pct range required to reduce both long- (8-hour) and short-term coal mine dust concentrations below federal requirements.