Generation of a microaerosol suitable for deposition in the peripheral airways

A method is described for the production of a dry submicronic aerosol. A wet aerosol is first produced in a common jet aerosol apparatus, modified to retain particles larger than 2 micrometers. The aerosol is then dried by heating to 70 degrees C in an evaporation tube. The dry particles are mainly smaller than 0.5 micrometer. At inhalation the temperature drops below 40 degrees C and the dew point is reached so that water vapour condenses on the particles. About 95% of the particles were deposited past the large bronchi and about 87% were retained in the alveoli. The new technique renders very satisfactory ventilation scintigraphies as proven by experience from more than 200 subjects. It may also prove useful for depositing drug aerosols in the peripheral airways.