The granulometric classification of aerosols using a new type of cascade impactor (four stage aerosol differential sampler).

The importance of classification of aerosols according to diametric size is well known. In fact it is possible to find a series of differential devices working on this principle ('Cascade Impactors' of May, Orr, Lippman, 'Eolic Classificator' of Zurlo, 'Centripeter Impactor' of Hounam and Sherwood, etc.). The big interest in this field has led us to devise a four-stage aerosol differential sampler with the following principal characteristics: (I) high efficiency and selectivity, (ii) simplicity of use and function, (iii) possibility of sampling high air volumes without conglomeration of particles in sampling surfaces, (iv) employment of usual collecting surfaces (microscope slides). The sampler gives satisfactory responses from all the above points of view.