Air Quality Impacts of a Scheduled 36-Hour Closure of a Major Highway

Details

• Personal Author:
  Choi W ; Paulson S ; Quiros D ; Wang R ; Winer A ; Zhang Q ; Zhu Y
• Description:
  On the July 16-17, 2011 weekend, a major Los Angeles highway, the I-405, was closed 36 hours for an overpass demolition. During this event we measured ultrafine particles (UFPs, < 0.1 micro-meters) and other air pollutants upwind, downwind, and at various distances of the I-405 pre-, during-, and post-closure using both fixed site and mobile platform monitors. We observed approximately 90% and approximately 40% traffic flow reductions on I-405 during closure on Saturday and Sunday, and approximately 20% reductions on the immediately adjacent Sepulveda Boulevard. During-closure downwind particle number concentration (PNC) decreased 73%, mass concentration (PM2.5) decreased 44%, and black carbon (BC) decreased 48%. We found traffic density (vehicles distance) correlated well with downwind BC (R-square=0.71). Daily average particle size distributions downwind were bimodal with pronounced nucleation and accumulation mode peaks during non-closure conditions and unimodal with an accumulation mode peak during closure conditions on Saturday July 16. We compared our current data to a similar dataset from 2001 and found that, over this 10-year period, the downwind-to-upwind PNC ratio decreased approximately 40%, but weekday traffic flow increased approximately 20%. This translates into an approximately 50% PNC reduction per-vehicle from the I-405 transit corridor. We speculate this decrease may have been from reduction of sulfur content in diesel fuels (from 500 to 15 ppm in 2006), the increased California Low-Emission Vehicle standards, and retirement of older vehicles. [Description provided by NIOSH]
• Subjects:
  Air Pollution Environmental Monitoring Occupational Health Particulate Matter Safety Transportation Ventilation
• Keywords:
  Air Monitoring Air Pollution Automotive Emissions Particulates
• Publisher:
  American Association for Aerosol Research
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  California ; Minnesota ; OSHA Region 5 ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• NIOSHTIC Number:
  nn:20055870
• Citation:
  Proceedings of the AAAR 31st Annual Conference, October 8-12, 2012, Minneapolis, Minnesota. Mount Laurel, NJ: American Association for Aerosol Research, 2012 Oct; :4UA.5
• CAS Registry Number:
  Carbon black (CAS RN 1333-86-4)
• Federal Fiscal Year:
  2013
• Performing Organization:
  University of California Los Angeles
• Peer Reviewed:
  False
• Start Date:
  20050701
• Source Full Name:
  Proceedings of the AAAR 31st Annual Conference, October 8-12, 2012, Minneapolis, Minnesota
• End Date:
  20270630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:64b87330f918995a08e550e7a486397320f16f6841640c4dd6cb2c3796632845d021ab798600863fd9984f8cf6330f7868d0e768d636ed9bada14a27d4f7710e
• Download URL:
  https://stacks.cdc.gov/view/cdc/213630/cdc_213630_DS1.pdf
• File Type:
  [PDF - 167.65 KB ]