Abstract: An enclosed spray chamber for the application of toxic compounds in micro liquid volumes as a function of time using air as a carrier. The spray chamber is cylindrical and vertically mounted about its longitudinal axis. A spray nozzle is mounted in the top of the spray chamber which uses a syringe and needle reservoir system as an accurate means of controlling the amount of solute dissipated. An air pump provides a stream of air that passes in front of the spray nozzle which pulls the spray solute and solvent out of the syringe by vacuum. An exhaust fan and exhaust outlet are provided to safely dispose of the spray solute and solvent outside of the working area of the chamber. A timer system operates the exhaust fan and air pump so that spray droplet fallout and impingement time can be varied and calibrated.