EVAPORATION OF AQUEOUS AEROSOLS PRODUCED BY JET NEBULIZERS - EFFECTS ON PARTICLE-SIZE AND CONCENTRATION OF SOLUTION IN THE DROPLETS

Aqueous droplets produced by jet nebulizers can lose water by evaporat ion prior to entry into the patient's mouth, or a sizing device. Evapo ration causes increase in the concentration of the solution in the dro plet and reduction in size. These changes can complicate interpretatio n of results from experiments such as in vitro particle sizing or huma n respiratory tract deposition. We present experimental data obtained by nebulization of isotonic saline using a variety of aerosol delivery systems employing jet nebulizers. The impact of the evaporation pheno mena is particularly great when a large volume of dry dilution air is mixed with the aerosol stream - a situation that is quite common in ae rosol experiments. The experimental results approach the values calcul ated from the theoretical mass balance models in the limit of equilibr ium between the droplets and the surrounding atmosphere.