The potential of air ionization to control dust and bacteria in livestock buildings was investigated, using a special chamber within an animal chamber. Insulation panels with exposed aluminium foil were glued to the walls and ceiling. All side walls were wired to a high voltage DC positive polarity power supply. The ceiling was negatively charged or attached to the ground depending on the experiment. Two types of electron generation systems were used for ionizing the air. It was found from the experiments that negatively ionized air is effective in reducing the concentration of airborne organisms in an animal isolation room; the reduction depends on aerosol infective dose, number of particles generated per unit time, natural resistance of exposed animal, defence mechanism of exposed animal. The use of negative ionized air is effective in reducing the aerosol concentration, depending on quantity of aerosol generated per unit time and the potential of re-entrainment of aerosol removed from the atmosphere.