A current NIOSH-funded research project aims to provide a basis for improved understanding of the physical factors that govern the performance of aerosol samplers. It is driven by the current interest in developing new occupational exposure standards of aerosol samplers. It is driven by the current interest in developing new occupational exposure standards for aerosols which better reflect human exposure. All the experimental research for that project has been completed. Final completion of the project, following analysis of the results and reporting, will be in March 1998 (extended from August 1997). That project has been very successful indeed in identifying new experimental methods, providing excellent and copious basic data on which to base the development of mathematically-accessible models for aerosol sampler performance. Such models look very promising for describing the performances of samplers like those used in practical industrial hygiene. This new project aims to build on the new knowledge that has been gained. Specifically, it will be used in the development of scaling laws by which samplers in conditions relevant to the full-scale occupational setting (dimensional scale, mode of use, particle size range, wind-speed, sampling flowrate, etc.) can be developed, tested and validated in a small wind tunnel like that used in the current research. Such an approach has already shown its potential for the rapid acquisition of copious performance data. New samplers arising from pilot development work using the new methodology will be tested against known 'reference' samplers in actual workplaces. It is expected that this research will lead to new protocols for the routine testing of aerosol sampler performance (including validation with respect to specific particle size-selective criteria) which will not require-as is currently the case-the use of very large wind tunnels and extensive labor resources. As a result, the new testing procedures will be quick and cost-effective. There is currently considerable interest in the international community (including both NIOSH and the EC) in achieving such improvements in new sampler testing and development methodologies.
