Development of aerosol number samplers using foam filters
Chen, C., Weng, Y., Lin, W., Kuo, Y., Chung, and Shih, T.
2002 American Industrial Hygiene Conference, AIHce PDCs - San Diego, June 1 - 2, paper 162
Chen, C., Weng, Y., Lin, W., Kuo, Y., Chung, and Shih, T., (2002), "Development of aerosol number samplers using foam filters", American Industrial Hygiene Conference, AIHce PDCs - San Diego, June 1 - 2, paper 162.
Abstract:
C. Chen, Y. Weng, W. Lin, National Taiwan University, Taipei, Taiwan Republic of China; Y. Kuo, Chung Hwa College of Medical of Technology, Tainan, Taiwan Republic of China; T. Shih, Council of Labor Affairs, Taipei, Taiwan Republic of China
Aerosol number concentration has been shown to serve as a better surrogate for aerosol mass concentration, because it yields a better correlation between exposure and disease for population exposure to ambient air. On the other hand, aerosol deposition in the respiratory tract strongly depends on aerosol size. Therefore, a size-selective aerosol number sampler is essential in order to accurately assess the extent of the health hazard of fine particulates.
Different porosities of polyurethane foam filters were used as the size-selective devices. Among the parameters operated were (a) foam porosity (ppi), (b) filter thickness, (c) face velocity, and (d) packing density of the foam filter. Di-octyl phthalate was used as test agent. A constant output atomizer and an ultrasonic atomizing nozzle were used to generate polydisperse submicrometer- and micrometer-sized particles, respectively. Aerosol concentrations and size distributions upstream and downstream of the foam filter were monitored by a scanning mobility particle sizer and an aerodynamic particle sizer. The aerosol output was neutralized by a radioactive source. The light-work ICRP deposition model was chosen as the primary target curve.
The results showed that the most penetrating size (also referred to as collection minimum) of the foam filter decreased as the foam porosity, packing density and face velocity increased. In this work, the highest foam porosity and packing density we could acquire were 100 ppi and 0.2, respectively. By adjusting the face velocity, the most penetrating size was able to move to 0.25 ¦Ìm, which is the most penetrating size of ICRP criterion. The whole aerosol penetration curve could further fit to the ICRP curve by adjusting the filter thickness. There are numerous ways to match the ICRP definition. Applying the parallel or serial combinations of different properties of foams provided a better fit to the ICRP or other deposition criterion.
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Lin, W. Aerosol Research and Exposure Assessment Laboratory, Department of Environmental Health, University of Cincinnati, Cincinnati, 0H45267-0056, USA