In a recent previous paper (Su & Vincent, J. Aerosol Sci. 33 (2002) 103) we described a new method by which to investigate the relationships between aspiration efficiency, particle inertia, gravitational effect and sampling orientation for aerosol sampling in perfectly calm air. All previous experimental work to elucidate the basic nature of aerosol sampling in calm air described has been carried out for thin-walled tubes, and none has yet been reported in relation to blunt samplers. To begin to fill this important gap, the present paper describes the application of our new method towards acquiring new measurements of aspiration efficiency for simple blunt samplers. Experiments were carried out to determine the aspiration efficiencies of simple, idealized, spherical blunt samplers for a range of sampling scenarios, for two sizes of blunt samplers and different sampling inlet diameters, and for upwards and downwards sampling scenarios (and hence a range of governing dimensionless physical quantities). It was shown that aspiration efficiency decreased both with increasing inertia (as represented by the Stokes' number) and with increasing gravitational effect (as represented by the ratio of particle settling velocity to the air velocity at the sampler inlet). The results enabled qualitative physical explanation of the difference between what was observed for upwards and downwards-facing sampling, respectively, in terms of (a) the role of the sampler body in deflecting the air flow in the region close to the body of the sampler (in turn influencing the performance of the sampler), and (b) the interception of particles in the downwards-facing scenario falling within the 'shadow' projected upwards by the sampler body. The significant contribution of this work has been the acquisition of a definitive set of new experimental data. These data will be valuable in the future development of understanding of the physics underlying aerosol sampler performance. Such knowledge will be of practical value because (a) blunt samplers are generally the most representative of the types of instruments used in practical occupational, and (b) calm or slowly moving air is characteristic of many indoor situations. (C) 2003 Elsevier Ltd. All rights reserved.