Effects of Window Openings on Children’s Exposure to Ultrafine Particles During School Bus Commutes in Los Angeles

Details

• Personal Author:
  Lee ES ; Zhu Y
• Description:
  Children are exposed to high levels of vehicle-emitted ultrafine particles (UFPs, diameter ≤ 100 nm) during school bus commuting. Previous studies found the in-cabin UFP concentrations were even higher inside school buses than the outside because school buses' own emission can infiltrate into the bus cabin (i.e., self-pollution). This study investigated to what extend different window conditions can change the in-cabin exposure levels and their spatial distributions at high driving speeds. Twelve school buses were evaluated on freeways and major arterial roadways in Los Angeles while measuring UFP concentrations at three in-cabin locations (i.e., front, middle, and rear) of school buses and on-road ambient. Data were collected under three window conditions: (1) all windows closed, (2) driver's window open, and (3) middle-windows open. Additionally, this study evaluated the change of in-cabin exposure levels when (4) emergency door gaps were sealed. For the closed window conditions, this study found overall UFP I/O was 1.18 (> 1.00; thus, self-pollution) on average across 12 school buses. The I/O ratio was the highest in the rear cabin (i.e., 1.60) because of self-pollution through the emergency door gaps; whereas, the front and middle provided 1.06 and 0.85, respectively. For open window conditions, the overall UFP I/O ratio increased to 1.61 while the driver's window was open and it also increased to 1.47 when middle-windows were open. Particularly in the rear cabin, UFP I/O significantly increased to 2.48 and 2.83 under these open window conditions, respectively; however, not in the front and the middle. Finally, the increased air-tightness of emergency door gaps provided a significant reduction of the overall UFP I/O by 0.29 to 0.62. The UFP I/O reduction was the greatest in the rear cabin by reducing the UFP I/O to 0.98 and the I/O ratios were maintained below 1.00 at the other in-cabin locations. [Description provided by NIOSH]
• Subjects:
  Air Pollution Occupational Health Particulate Matter Safety Transportation
• Keywords:
  Air Air Pollution Author Keywords: Indoor Environment Automotive Emissions Children Particulate Matter Particulates Southwest-specific Ultrafine Particles
• Publisher:
  International Society of Exposure Science
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• 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:
  70
• NIOSHTIC Number:
  nn:20055982
• Citation:
  25th Annual Conference of the International Society of Exposure Science (ISES 2015), October 18-21, 2015, Henderson, Nevada. Herndon, VA: International Society of Exposure Science, 2015 Oct; :70
• Federal Fiscal Year:
  2016
• Performing Organization:
  University of California Los Angeles
• Peer Reviewed:
  False
• Start Date:
  20050701
• Source Full Name:
  25th Annual Conference of the International Society of Exposure Science (ISES 2015), October 18-21, 2015, Henderson, Nevada
• End Date:
  20270630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:d4ccff888319f1fae104ce5252996c7f2296d3c157e12c777d23148a19412b63033621c3aacf6e4abf0e790080bc7aa8f3530664f0a36558ca9dd143b795f802
• Download URL:
  https://stacks.cdc.gov/view/cdc/213715/cdc_213715_DS1.pdf
• File Type:
  [PDF - 295.66 KB ]