A Multi-Zone Model Evaluation of the Efficacy of Upper-Room Air Ultraviolet Germicidal Irradiation

Details

• Personal Author:
  Miller SL ; Nicas M
• Description:
  Engineering controls can be used to reduce the spread of airborne infectious disease, particularly tuberculosis (TB), in high-risk settings. This article evaluates published data on the efficacy of upper-room air ultraviolet germicidal irradiation (UVGI). A three-zone representation of a TB patient room equipped with a germicidal UV lamp is developed. The lamp irradiates the upper-room zone and inactivates airborne mycobacteria; the unirradiated lower-room zone also contains a near-field zone surrounding the TB patient. Infectious particles are generated in the near-field zone and transported throughout the room by air flow between zones. Each zone is independently well-mixed; the whole room, however, is not well-mixed. The three-zone model is applied to a previously published study of UVGI against airborne mycobacteria in a test room. Based on the estimated slopes of the semi-log concentration decay curves for viable mycobacteria, and on the assumption that the test room was essentially well-mixed, the published study reported that UVGI provided 10 to 25 equivalent air changes per hour. However, when the same decay curve slopes are interpreted in the context of the three-zone model, UVGI is seen to be far less effective in reducing exposure intensity near the TB patient. Near-field exposure intensity is relevant because health care workers are usually in close proximity to the TB patients they attend. In general, the interpretation of concentration decay data depends on the specific model of room air mixing that is assumed appropriate. It is recommended that tests of the efficacy of UVGI and other control devices against airborne microorganisms be based on steady-state concentration measurements rather than concentration decay measurements, because the former measurements do not require inferences based on a particular model. [Description provided by NIOSH]
• Subjects:
  Aerosols Air Pollutants, Occupational Communicable Disease Control Communicable Diseases Engineering Health Care Facilities Workforce And Services Health Personnel Occupational Health Particulate Matter Radiation Risk Assessment Risk Factors Safety Tuberculosis Ultraviolet Rays

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• Keywords:
  Aerosol-particles Aerosol-sampling Airborne-particles Analytical-models Author Keywords: Tuberculosis Disease-control Disease-incidence Disease-transmission Engineering-controls Germicides Health-care-facilities Health-care-personnel Infection-control Infectious-diseases Multi- Zone Modeling Risk-analysis Risk-factors Simulation-methods Ultraviolet-radiation Ultraviolet Germicidal Radiation

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• ISSN:
  1047-322X
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  California ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  317-328
• Volume:
  14
• Issue:
  5
• NIOSHTIC Number:
  nn:20024405
• Citation:
  Appl Occup Environ Hyg 1999 May; 14(5):317-328
• Contact Point Address:
  Mark Nicas, Center for Occupational and Environmental Health, School of Public Health, University of California, Berkeley, California, USA
• Federal Fiscal Year:
  1999
• NORA Priority Area:
  Research Tools and Approaches: Risk Assessment Methods
• Performing Organization:
  University of California-Berkeley, School of Public Health, Center for Occupational and Environmental Health, Berkeley, CA 94720
• Peer Reviewed:
  True
• Start Date:
  19960701
• Source Full Name:
  Applied Occupational and Environmental Hygiene
• End Date:
  19990630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:6a77ef71676e15a627dbd59529872781b97ec097dea525187627f13f3dcf55d6bad7677e319a1e2017d05fbdf8da5f1cb559eb980315c257dc21efce1aceaea0
• Download URL:
  https://stacks.cdc.gov/view/cdc/196222/cdc_196222_DS1.pdf
• File Type:
  [PDF - 439.83 KB ]