Abstract
In order to make clear how much extent urban aerosol particles are inactivated as con-densation nuclei, possibly by the effect of organic materials, an experimental study was made using a vertical thermal diffusion chamber and an impactor. Inactive particles, which grew slowly or not at all under the supersaturation less than about 1%, were collected separated from active particles, and the concentration of inactive particles was compared with that of atmospheric aerosol particles by means of a transmission electron microscope. It was found that inactive particles scarcely existed. This result indicates that most of the atmospheric aerosol particles are not greatly inactivated as condensation nuclei even in the possible pres-ence of organic materials in the urban area.
