Efficacy of Ventilation, HEPA Air Cleaners, Universal Masking, and Physical Distancing for Reducing Exposure to Simulated Exhaled Aerosols in a Meeting Room

Details

• Personal Author:
  Beezhold, Donald H. ; Blanchere, Francoise M. ; Boots T ; Coyle JP ; Derk RC ; Fotta SA ; Lemons, Angela R. ; Lindsley, William G. ; Martin SB Jr. ; McKinney WG ; Mead, Kenneth R. ; Noti JD ; Reynolds JS ; Sinsel EW
• Description:
  There is strong evidence associating the indoor environment with transmission of SARS-CoV-2, the virus that causes COVID-19. SARS-CoV-2 can spread by exposure to droplets and very fine aerosol particles from respiratory fluids that are released by infected persons. Layered mitigation strategies, including but not limited to maintaining physical distancing, adequate ventilation, universal masking, avoiding overcrowding, and vaccination, have shown to be effective in reducing the spread of SARS-CoV-2 within the indoor environment. Here, we examine the effect of mitigation strategies on reducing the risk of exposure to simulated respiratory aerosol particles within a classroom-style meeting room. To quantify exposure of uninfected individuals (Recipients), surrogate respiratory aerosol particles were generated by a breathing simulator with a headform (Source) that mimicked breath exhalations. Recipients, represented by three breathing simulators with manikin headforms, were placed in a meeting room and affixed with optical particle counters to measure 0.3-3 µm aerosol particles. Universal masking of all breathing simulators with a 3-ply cotton mask reduced aerosol exposure by 50% or more compared to scenarios with simulators unmasked. While evaluating the effect of Source placement, Recipients had the highest exposure at 0.9 m in a face-to-face orientation. Ventilation reduced exposure by approximately 5% per unit increase in air change per hour (ACH), irrespective of whether increases in ACH were by the HVAC system or portable HEPA air cleaners. The results demonstrate that mitigation strategies, such as universal masking and increasing ventilation, reduce personal exposure to respiratory aerosols within a meeting room. While universal masking remains a key component of a layered mitigation strategy of exposure reduction, increasing ventilation via system HVAC or portable HEPA air cleaners further reduces exposure. [Description provided by NIOSH]
• Subjects:
  Aerosols Communicable Diseases Occupational Health Personal Protective Equipment Respiratory System Safety Ventilation
• Keywords:
  Author Keywords: Indoor Exposure Breathing COVID-19 Disease Transmission Exposure Assessment HEPA Air Cleaner Indoor Environments Personal Protection Physical Distancing SARS-CoV-2 Simulation Methods Universal Masking Ventilation Ventilation Systems

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• ISSN:
  1999-4915
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  Ohio ; OSHA Region 3 ; OSHA Region 5 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division ; RHD - Respiratory Health Division ; DFSE - Division of Field Studies and Engineering ; OD - Office of the Director
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  13
• Issue:
  12
• NIOSHTIC Number:
  nn:20064315
• Citation:
  Viruses 2021 Dec; 13(12):2536
• Contact Point Address:
  William G. Lindsley, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA
• Email:
  wlindsley@cdc.gov
• Federal Fiscal Year:
  2022
• NORA Priority Area:
  Healthcare and Social Assistance ; Construction
• Peer Reviewed:
  True
• Source Full Name:
  Viruses
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:7dc847c09aedf140bc731323e8446b4703641ae07d6ad9e7b7238120dab30b8f7dcaa9b938d34d035f87873a0fe7fec262d5d13dcaf290925445e82b6de3b57d
• Download URL:
  https://stacks.cdc.gov/view/cdc/222806/cdc_222806_DS1.pdf
• File Type:
  [PDF - 168.02 KB ]