A new efficient cell was developed to generate a large quantity of aerosol using an ultrasonic nebulizer. The currently used conventional pail-type cell cannot generate such a large quantity of aerosol because a large portion of the mist is lost by agglomeration and subsequent liquefaction onto the cell wall and liquid surface. The newly developed cell is a chimney-type cell characterized by the attachment of a vertical cylinder at its center and a partition to separate the cell into upper and lower compartments, each of which is supplied with a carrier air flow. The mist emanating from the fluid surface is carried upward through the vertical cylinder by a laminar primary airflow. The secondary airflow served to sheath the primary airflow containing the mist and to prevent the impact and adhesion of the mist on the surrounding wall. The nebulizing rate of Ti02 suspension was found to be three times higher with the chimney-type than with the pail-type. No differences were found between the two types in terms of particle diameters, particle size distribution, and the electron microscopic images of the aerosol. It was concluded that a commercially available ultrasonic nebulizer equipped with the chimney-type cell allowed generation of a large quantity of aerosol for use in inhalation animal experiments.