Pneumatic Powder dispersion techniques using airstream, fluidized beds and fluid energy jet mills have been used as dry powder aerosol generators in inhalation studies and for calibration of aerosol instruments. Most powder dispersers have certain limitations on test materials and maximum/minimum aerosol concentrations that can be achieved. The Wright Dust Feeder is good for test materials that form a stable cake under compression, and the fluidized bed generator is useful for free-flowing materials, but neither is suitable for use with sticky powders. For nose-only inhalation exposure systems, generators that can operate at low flow rates, ranging from 10 to 60 L/min. are needed. The Wright dust feeder and the fluidized bed generators can be operated at the required flow rates for certain powders, but are difficult to operate with sticky powders such as TiO2. The following two powder generators were developed for use with the sticky powders.