The Constant Flow Nebulizer is designed to act as an aerosol source capable of operating for a period of 8.5 hours without refilling. It has been particularly useful to produce low concentration aerosols from suspensions or solutions for use in Nose-Only Plenums and Whole Body animal exposure chambers in toxicity studies. At 25 psig the Constant Flow Nebulizer generates 0.588 ml per minute and uses 6.5 liters per minute of air. The nebulization rate is 74µl per liter of air. The aerosol is constantly recirculated in the nebulizer by use of a peristaltic pump.