A new concept for personal aerosol sampling was developed by Drs. Grinshpun and Willeke during the period of 1995-97. They designed a prototype sampler with a curved, porous inlet and a 25-mm collection filter directly behind the inlet. The design allowed avoiding transmission losses in the sampler and made its aspiration efficiency less sensitive to the ambient wind speed. The preliminary study demonstrated several advantageous features of the new device: the physical sampling efficiency of the device was confirmed to have low sensitivity to ambient air conditions, such as wind speed and direction; and the filter samples showed high uniformity of the particle deposits. The sampler prototype was further modified by SKC Inc. that made it commercially available in 1997 (marketed as the "Button Aerosol Sampler"). This grant was funded by NIOSH in 1998 to evaluate the performance of the new Button Aerosol Sampler in the laboratory and in the field. The primary goal was to determine whether the new concept and device can be successfully utilized for the assessment of worker exposure in occupational environments contaminated with airborne dust and microorganisms. The device was tested under various environmental conditions (including wind speed and direction) and different sampling modes. A considerable database was established for airborne particles of different concentration levels and sizes ranging from respirable particles to "very large" particles (beyond the upper limit of the inhalability convention, i.e., >100 !.tm). In addition to non- biological particles, the sampler was tested with viable microorganisms, including seven species of bacteria and fungi. The performance of the new sampler was compared with four other commercially available aerosol samplers designed for personal and stationary sampling. The laboratory evaluation of the Button Personal Aerosol Sampler was conducted in three wind tunnels featuring different designs, test zone dimensions, and aerosol generation systems. One of these was a small wind tunnel built in the Aerospace Laboratory of the University of Cincinnati College of Engineering. The second was a large walk-in wind tunnel facility made available through our collaboration with the Alice Hamilton Laboratory, NIOSH-Cincinnati. The third one was a newly-designed open-area wind tunnel built in our laboratory in the Department of Environmental Health at the University of Cincinnati. The sampler was first tested while freely-suspended. Then experiments were conducted while the sampler was mounted on either a full-size manikin, a simplified torso, or a small plate. As an important outcome of this effort, a new simplified protocol was developed for testing personal aerosol samplers in small wind tunnels at relatively low operational cost. The new testing facility was built in the Department of Environmental Health at the University of Cincinnati and is now available for testing other personal aerosol samplers. The laboratory evaluation of the Button Sampler performance and its comparison with the 10M sampler and the 37-mm closed-face cassette as well as with two bioaerosol samplers, such as the Burkard personal volumetric air sampler and the Air-a-Cell, showed that the Button Sampler is suitable and can be advantageous for measuring airborne particles and microorganisms in various environments, including workplaces. The sampler was tested with spores of actinomycetes and other bacterial and fungal spores, as well as with vegetative cells, which are common in industrial, agricultural, and health-care environments. The field evaluation of the Button Personal Aerosol Sampler was performed in occupational environments with different sources of airborne particles that in turn had different particle characteristics, such as the size distribution, concentration, and chemical composition. For example, the sampler was used to assess the metal exposure among abrasive blasting workers at four U.S. Air Force Bases and among workers performing active lead abatement and post- abatement cleaning in indoor environments. In environments with extremely high concentrations of very large, projected particles (beyond the inhalability convention range), the new sampler was used with an external protective screen. Overall, the field studies have shown that the Button Sampler can be successfully used in occupational environments for assessing the worker exposures. All the work initially proposed in the grant application (Specific Aims A through G, see below) has been accomplished. None of the specific aims indicated in the grant application has been modified.
S.A. Grinshpun, Center for Health Related Aerosol Studies, Department of Environmental Health, University of Cincinnati, P.O. Box 670056, Cincinnati, OH 45267-0056