A canine inhalation exposure apparatus has been constructed which incorporates a whole body plethysmograph with the normal dry box arrangement. The dog's respiration causes air to move in and out of the plethysmograph through a pneumotachograph producing a signal proportional to respiratory flow rate which, when integrated, also yields tidal volume information. The main advantage of this system is that respiratory measurements can be made during exposure without encumbering the nose with a respiratory mask and valving arrangement. The aerosol is continuously produced, drawn past the dog's nose and collected in overflow filters during exposure. In this manner, the dog is exposed to fresh aerosol with each inspiration and the mean aerosol concentration during exposure can be obtained by determining the amount of radioactivity in the dog and the overflow filters after the exposure.