Single stage impactors with penetration characteristics approximating those of the BMRC, AEC and ACGIH respirable criteria have been developed for use as personal samplers. Three impactors were built for flow rates of 2 L/min. Experimental calibration data of these impactors are compared to the respective respirable criteria for which they were designed. Oil soaked impaction plates were used in these impactors so particles impacting on the plates would always strike an oiled surface and not bounce from the plate. Experiments with coal dust using these plates showed little particle bounce. Finally, a procedure is introduced by which samplers can be designed with penetration characteristics that differentiate between the AEC and ACGIH respirable criteria.