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Design and evaluation of advanced electrostatic sampler for total bioaerosols.

Mainelis-G; White-L; Lioy-PJ
Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R21-OH-008656, 2009 Oct; :1-81
Exposure to airborne biological agents, especially to pathogenic or allergenic microorganisms, is known to cause a wide range of respiratory and other health disorders in occupational and general populations. To improve exposure assessment and control, and to protect the populations and resources potentially exposed to airborne microbial agents, we evaluated a feasibility of a novel bioaerosol sampler capable of achieving very high sample concentration rates. High sample concentration rates allow detecting low microorganism concentrations thus improving our understanding of a relationship between biological exposures and health outcomes. Airborne particles drawn into the sampler are electrostatically deposited onto a narrow collection electrode covered with superhydrophobic substance. The chamber is positioned at a small angle to the horizontal and a small liquid droplet introduced at the top of the collection chamber rolls down under gravity and collects the deposited particles. Sampler's performance was analyzed with non-biological and biological particles; collecting droplet volumes from 5 to 60 uL, and sampling flow rates from 2 to 10 L/min. It was found that the vast majority of particles deposited onto the electrode are removed by the first rolling droplet. When testing with polystyrene latex particles of 3.2 um and the collecting droplet of 5 uL we achieved an unprecedented sample concentration rate as high as 1.2x I 0 6. These concentration rates were sustained for sampling times as long as 60 min. Experiments with the two common test bacteria (Pseudomonas fluorescens and Bacillus subtilis) have shown that the novel bioaerosol sampler can also efficiently collect and concentrate airborne bacteria in small amounts of liquid (5 or 40 uL). For 10 min sampling, the collection efficiencies for both bacteria ranged from 50 to 72% and were substantially higher compared to the collection efficiencies for PSL particles of similar size. When used with 5 uL collection droplet and 10 L/min sampling flow rate, the EPSS achieved sample concentration rates of 1.2x10 6/min which are higher than those achieved by current bioaerosol samplers. The sampler's performance was also analyzed with three common fungi (Cladosporium cladosporioides, Penicillium melinii, and Aspergillus versicolor) and it achieved concentration rates ranging from 1x10(5)s to 3x10(5)/min when tested with airborne spore concentrations of 10(2) -10(3)/L (10(5)-10(6)/m3. For fungal concentrations commonly encountered in the ambient environment (10(3)-10(4)m3) the concentration rate of the EPSS approached 10(6)/min and higher. In addition, we successfully developed and applied an ATP-based bioluminescence method to quantify the collected fungal spores. The spore concentrations determined by microscopy and the A TP-based method were not statistically different. In fact, the ATP-based method allowed us to analyze spore concentrations that were too low to reliably detect by microscopy. The development of the new bioaerosol sampling concept introduces a new and efficient tool for determining exposure to airborne microorganisms in residential, occupational and environmental settings, thus improving our ability to protect populations at risk. The use of small collection liquid quantities makes the sampler compatible with various "laboratories on a chip" and may lead to near real-time determination of airborne microbial contaminants. Future studies will design a new particle charging unit, will develop field-deployable sampler and will test it exhaustively in various laboratory and field environments. Upon successful testing, the new sampler could be deployed in various occupational environments.
Exposure-levels; Airborne-particles; Biological-material; Pathogens; Microorganisms; Respiratory-irritants; Respiration; Respiratory-system-disorders; Pulmonary-function; Pulmonary-system; Pulmonary-system-disorders; Pulmonary-disorders; Sampling-equipment; Analytical-processes; Particulates; Bacteria; Fungi; Risk-factors
Gediminas Mainelis, Ph.D., Office of Research and Sponsored Programs, Rutgers, The State University of New Jersey, 3 Rutgers Plaza, New Brunswick, New Jersey 08901
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Final Grant Report
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National Institute for Occupational Safety and Health
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Rutgers the State of New Jersey - New Brunswick