This article presents the indigenous design and develop-ment of the BARC aerodynamic size separator (BASS), which separates aerosol particles into seven size classes ranging from 0.53 to 10 µm based on impaction, and operates at a flow rate of 45 1pm. Unlike most com-mercially available impactors, BASS can be configured with the desired number of stages up to a maximum of seven. Inter-comparison studies between standard Andersen Mark-II cascade impactor and BASS, have shown consistently good performance by BASS in all respects. BASS has also been tested for its cut-off diameter characteristics and impaction stage response function, which have been found satisfactory. It is expected that this development will open up avenues for making size separators available at a relatively low cost, thereby giving an impetus for their wider use in the field of air pollution and aerosol research.