Simultaneously Reducing CO2 and Particulate Exposures via Fractional Recirculation of Vehicle Cabin Air

Details

• Personal Author:
  Grady ML ; Jung HS ; Miller AL ; Victoroff T
• Description:
  Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO2) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle. Operating the recirculation system with a standard cabin filter reduced particle concentrations to 1000 particles/cm3, although CO2 levels rose to 3000 ppm. When as little as 25% fresh air was introduced (75% recirculation), CO2 levels dropped to 1000 ppm, while particle concentrations remained below 5000 particles/cm3. We found that nanoparticles were removed selectively during recirculation and demonstrated the trade-off between cabin CO2 concentration and cabin particle concentration using fractional air recirculation. Data showed significant increases in CO2 levels during 100% recirculation. For various fan speeds, recirculation fractions of 50-75% maintained lower CO2 levels in the cabin, while still reducing particulate levels. We recommend fractional recirculation as a simple method to reduce occupants' exposures to particulate matter and CO2 in vehicles. A design with several fractional recirculation settings could allow air exchange adequate for reducing both particulate and CO2 exposures. Developing this technology could lead to reductions in airborne nanoparticle exposure, while also mitigating safety risks from CO2 accumulation. [Description provided by NIOSH]
• Subjects:
  Air Movements Air Pollutants, Occupational Air Pollution Automobiles Carbon Dioxide Confined Spaces Engineering Environmental Exposure Environmental Pollution Filtration Occupational Health Particulate Matter Safety Ventilation

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• Keywords:
  Air Analysis Air Contaminants Air Flow Air Quality Air Quality Measurement Air Treatment Author Keywords: Automobile Carbon Dioxide CO2 Exposure Confined Spaces Engineering Controls Environmental Pollution Environmental Technology Equipment Design Equipment Testing Exposure Assessment Humans Motor Vehicles Nanoparticles Nanotechnology Particle Exposure Particulates Ultrafine Particles Ventilation Systems

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• Series:
  Mining Publications
• ISSN:
  1352-2310
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  California ; OSHA Region 10 ; OSHA Region 9 ; Washington
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  SMRD - Spokane Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  77-88
• Volume:
  160
• NIOSHTIC Number:
  nn:20049725
• Citation:
  Atmos Environ 2017 Jul; 160:77-88
• Contact Point Address:
  Heejung S. Jung, Department of Mechanical Engineering, University of California, 900 University Ave, Riverside, CA, USA
• Email:
  heejung@engr.ucr.edu
• CAS Registry Number:
  Carbon dioxide (CAS RN 124-38-9)
• Federal Fiscal Year:
  2017
• Peer Reviewed:
  True
• Source Full Name:
  Atmospheric Environment
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:dfb4904132ec0c66de1180413ac426a874422c67e38c50b73045f06804d634de9f2584f0b635e97ca0a5e803977459248a7a16722a7ad8a6891df6999a91c6bd
• Download URL:
  https://stacks.cdc.gov/view/cdc/228417/cdc_228417_DS1.pdf
• File Type:
  [PDF - 2.13 MB ]