Laboratory production of ammonium and ferric sulfate aerosols

Since sulfate aerosol particles are an environmental factor of possible concern, laboratory studies are being conducted to determine their health effects. It is important in such studies that aerosols be controlled and monitored. Submicron sulfate aerosols at high (greater than 80%) and low (30-40%) relative humidities were generated and characterized in support of animal inhalation experiments. Aqueous solutions of ammonium sulfate and ferric sulfate were aerosolized with a compressed air nebulizer, dried, discharged and passed into an aerosol chamber. Aerosol characterization was performed using cascade impactors, electron microscopy, filter samples and an electrical mobility analyzer. Parameters measured included particle size distribution and mass concentration. Instruments used for sizing the aerosols were compared. The electrical mobility analyzer provided useful information on the time stability of the particle size and the mass concentration, but agreement between this instrument and electron microscopy or cascade impaction was poor.