A new type glass cascade impactor having round jets was designed. The frequency distributions of particle size in each 3 or 5 stages were determined, and studied on the microscopic counting technique, the efficiency of adhesive agents as slide glass treatment for sampling, and the effect of the volume and velocity of air sampling. This impactor can divide particles (0.45∼19μ) into 3 or 5 sizes, and the impactor having 3 stages is suitable for field test.
