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Airborne Microorganisms

The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Kevin G Kerr – 1st expert on this subject based on the ideXlab platform

  • methodology for determining the susceptibility of Airborne Microorganisms to irradiation by an upper room uvgi system
    Journal of Aerosol Science, 2006
    Co-Authors: Clive B Beggs, Catherine J Noakes, L. A. Fletcher, P Andrew Sleigh, Kevin G Kerr

    Abstract:

    Abstract Whilst a number of researchers have demonstrated the disinfection effectiveness of upper-room UV irradiation devices against a range of Airborne Microorganisms, it is technically difficult to determine the performance of such systems because the biological and physical processes involved can be complex. In particular, most of the quantitative data on the susceptibility of Airborne Microorganisms to UV irradiation is obtained from single-pass experiments which are not representative of the fragmented UV exposure experienced by Airborne Microorganisms in real rooms. This paper presents complete and partial mixing models for predicting an effective UV susceptibility constant, Z eff , that is appropriate for quantifying the behaviour of Airborne Microorganisms when irradiated using an upper-room system. The use of both decay and continuous contamination experimental techniques are discussed and related to the models presented. Experimental results are presented which indicate that Z eff for Serratia marcescens is up to an order of magnitude lower than the susceptibility constants derived from single-pass experiments, suggesting that using these data to design upper-room UV systems may lead to a lower than expected performance.

  • development of a numerical model to simulate the biological inactivation of Airborne Microorganisms in the presence of ultraviolet light
    Journal of Aerosol Science, 2004
    Co-Authors: Catherine J Noakes, L. A. Fletcher, Clive B Beggs, P Andrew Sleigh, Kevin G Kerr

    Abstract:

    The effectiveness of any ultraviolet germicidal irradiation (UVGI) system is governed by the passage of Airborne Microorganisms through the UV field. This paper describes a new method for evaluating the performance of UVGI devices using computational fluid dynamic (CFD) simulations. A microorganism inactivation equation is combined with a scalar transport equation to describe the concentration of Airborne Microorganisms in the presence of a UV field. The solution of this equation, in conjunction with the momentum and turbulent energy equations, allows the effect of both the airflow and the UV field on the microorganism distribution to be examined. Solutions are shown for the airflow and microorganism concentration through a bench scale flow apparatus, at five different UV intensities. The results from the CFD model are validated against the experimental data, obtained from the flow apparatus, for aerosolised Pseudomonas aeruginosa Microorganisms. Good comparisons are seen, giving confidence in the application of the technique to other situations.

Sergey A. Grinshpun – 2nd expert on this subject based on the ideXlab platform

  • sampling for Airborne Microorganisms
    , 2007
    Co-Authors: Sergey A. Grinshpun, Mark P Buttner, Gediminas Mainelis, Klaus Willeke

    Abstract:

    Microbiologists have confronted the challenges of sampling and analysis of Airborne Microorganisms since the early 20th century. Today, the concentration and composition of Airborne Microorganisms are of interest in various areas such as agricultural and industrial settings, hospitals, home and office environments, and military installations. In all of these applications, the term “bioaerosol” is used to refer to Airborne biological particles, such as bacterial cells, fungal spores, viruses, and pollen grains, and to their fragments and by-products. A wide variety of bioaerosol sampling and analysis methods have been used, and new methods are being developed. However, no single sampling method is suitable for the collection and analysis of all types of bioaerosols and no standardized protocols are currently available. Therefore, data from different studies are often difficult to compare because of differences in sampler designs, collection times, airflow rates, collection media and analysis methods. In addition, human exposure limits have not been established for bioaerosols because of the lack of exposure, dose, and response data.
    The purpose of this chapter is to present various bioaerosol sampling and analysis methods that would allow facilitating an intelligent selection of instrumentation and techniques. The principles of bioaerosol sampling are presented, followed by a review of traditional and emerging sampling methods and techniques, including the results of performance evaluations of the various sampler types. Equipment calibration and air sampling considerations such as collection times and the number of samples are discussed. The advantages and disadvantages of surface sampling methods are also described.

  • assessment of electrical charge on Airborne Microorganisms by a new bioaerosol sampling method
    Journal of Occupational and Environmental Hygiene, 2004
    Co-Authors: Klaus Willeke, Tiina Reponen, Gediminas Mainelis, Atin Adhikari, Hongxia Wang, Sergey A. Grinshpun

    Abstract:

    Bioaerosol sampling is necessary to monitor and control human exposure to harmful Airborne Microorganisms. An important parameter affecting the collection of Airborne Microorganisms is the electrical charge on the Microorganisms. Using a new design of an electrostatic precipitator (ESP) for bioaerosol sampling, the polarity and relative strength of the electrical charges on Airborne Microorganisms were determined in several laboratory and field environments by measuring the overall physical collection efficiency and the biological collection efficiency at specific precipitation voltages and polarities. First, bacteria, fungal spores, and dust dispersed from soiled carpets were sampled in a walk-in test chamber. Second, a simulant of anthrax-causing Bacillus anthracis spores was dispersed and sampled in the same chamber. Third, bacteria were sampled in a small office while four adults were engaged in lively discussions. Fourth, bacteria and fungal spores released from hay and horse manure were sampled in a…

  • collection of Airborne Microorganisms by a new electrostatic precipitator
    Journal of Aerosol Science, 2002
    Co-Authors: Gediminas Mainelis, Klaus Willeke, Tiina Reponen, Atin Adhikari, Sergey A. Grinshpun

    Abstract:

    Bioaerosol exposure assessment and the protection of civil/governmental/military establishments from bioterrorism require the development of low-power bioaerosol collectors that are able not only to efficiently collect Airborne Microorganisms, but also to preserve their biological integrity. In search for such a method, a new bioaerosol sampler was evaluated. In this device, the Airborne Microorganisms are imparted electrical charges and are then deposited in an electrical field onto a growth medium (agar). Experiments were conducted with Pseudomonas fluorescens vegetative cells, Bacillus subtilis var. niger (BG) endospores (used to simulate the spores of anthrax-causing Bacillus anthracis when testing bioaerosol sensors) and Penicillium brevicompactum fungal spores. It was found that 80–90% of initially “charge-neutralized” biological particles were removed from the air, when a small amount of ionization was generated in the electrostatic precipitator’s (ESP) inlet and a precipitation voltage of ±4000V was applied across the agar plates. Over 70% of viable BG and P. brevicompactum spores entering the ESP were enumerated as colony forming units. The bioefficiency of the new sampler was about the same as that of the Biosampler, which was tested in parallel. In experiments with sensitive P. fluorescens vegetative cells, the ESP enumerated twice as many cells as the Biosampler. The latter result indicates that the electrostatic collection method may be especially useful for the collection and enumeration of sensitive Airborne Microorganisms. Experiments investigating the effect of aging time on the amount of electrical charge carried by the Airborne Microorganisms showed that the level of electrical charge gradually decreases with increasing aging time. However, even after the P. fluorescens cells had remained Airborne for an hour, they retained enough electrical charge to be collected with efficiency higher than 70%.

Catherine J Noakes – 3rd expert on this subject based on the ideXlab platform

  • methodology for determining the susceptibility of Airborne Microorganisms to irradiation by an upper room uvgi system
    Journal of Aerosol Science, 2006
    Co-Authors: Clive B Beggs, Catherine J Noakes, L. A. Fletcher, P Andrew Sleigh, Kevin G Kerr

    Abstract:

    Abstract Whilst a number of researchers have demonstrated the disinfection effectiveness of upper-room UV irradiation devices against a range of Airborne Microorganisms, it is technically difficult to determine the performance of such systems because the biological and physical processes involved can be complex. In particular, most of the quantitative data on the susceptibility of Airborne Microorganisms to UV irradiation is obtained from single-pass experiments which are not representative of the fragmented UV exposure experienced by Airborne Microorganisms in real rooms. This paper presents complete and partial mixing models for predicting an effective UV susceptibility constant, Z eff , that is appropriate for quantifying the behaviour of Airborne Microorganisms when irradiated using an upper-room system. The use of both decay and continuous contamination experimental techniques are discussed and related to the models presented. Experimental results are presented which indicate that Z eff for Serratia marcescens is up to an order of magnitude lower than the susceptibility constants derived from single-pass experiments, suggesting that using these data to design upper-room UV systems may lead to a lower than expected performance.

  • development of a numerical model to simulate the biological inactivation of Airborne Microorganisms in the presence of ultraviolet light
    Journal of Aerosol Science, 2004
    Co-Authors: Catherine J Noakes, L. A. Fletcher, Clive B Beggs, P Andrew Sleigh, Kevin G Kerr

    Abstract:

    The effectiveness of any ultraviolet germicidal irradiation (UVGI) system is governed by the passage of Airborne Microorganisms through the UV field. This paper describes a new method for evaluating the performance of UVGI devices using computational fluid dynamic (CFD) simulations. A microorganism inactivation equation is combined with a scalar transport equation to describe the concentration of Airborne Microorganisms in the presence of a UV field. The solution of this equation, in conjunction with the momentum and turbulent energy equations, allows the effect of both the airflow and the UV field on the microorganism distribution to be examined. Solutions are shown for the airflow and microorganism concentration through a bench scale flow apparatus, at five different UV intensities. The results from the CFD model are validated against the experimental data, obtained from the flow apparatus, for aerosolised Pseudomonas aeruginosa Microorganisms. Good comparisons are seen, giving confidence in the application of the technique to other situations.

  • Development of a numerical model to simulate the biological inactivation of Airborne Microorganisms in the presence of ultraviolet light
    Journal of Aerosol Science, 2004
    Co-Authors: Catherine J Noakes, L. A. Fletcher, Clive B Beggs, P Andrew Sleigh, K. G. Kerr

    Abstract:

    The effectiveness of any ultraviolet germicidal irradiation (UVGI) system is governed by the passage of Airborne Microorganisms through the UV field. This paper describes a new method for evaluating the performance of UVGI devices using computational fluid dynamic (CFD) simulations. A microorganism inactivation equation is combined with a scalar transport equation to describe the concentration of Airborne Microorganisms in the presence of a UV field. The solution of this equation, in conjunction with the momentum and turbulent energy equations, allows the effect of both the airflow and the UV field on the microorganism distribution to be examined. Solutions are shown for the airflow and microorganism concentration through a bench scale flow apparatus, at five different UV intensities. The results from the CFD model are validated against the experimental data, obtained from the flow apparatus, for aerosolised Pseudomonas aeruginosa Microorganisms. Good comparisons are seen, giving confidence in the application of the technique to other situations. © 2003 Elsevier Ltd. All rights reserved.