Size Distribution and Diurnal and Seasonal Trends of Ultrafine Particles in Source and Receptor Sites of the Los Angeles Basin

Details

• Personal Author:
  Hinds WC ; Kim S ; Shen S ; Sioutas C ; Zhu Y
• Description:
  This paper presents results from a study conducted in two urban areas of southern California, Downey and Riverside, to examine the effect of different sources and formation mechanisms on the size distribution and temporal trends of ultrafine particles. Near-continuous data were collected for 5 months at each location. Our data clearly identified Downey as a source site, primarily affected by vehicular emissions from nearby freeways, and Riverside as a receptor site, where photochemical secondary reactions form a substantial fraction of particles, along with local vehicular emissions. In Downey, the diurnal trends of total particle number concentration and elemental carbon (EC) appear to be almost identical throughout the day and irrespective of season, thereby corroborating the role of primary emissions in the formation of these particles. This agreement between EC and particle number was not observed in Riverside during the warmer months of the year, while very similar trends to Downey were observed during the winter months in that area. Similarly, the size distribution of ultrafine particles in Downey was generally unimodal with a mode diameter of 30-40 nm and without significant monthly variations. The number-based particle size distributions obtained in Riverside were bimodal, with a significant increase in accumulation mode as the season progressed from winter to summer. During the warmer months, there was also an increase in sub-100-nm particles in the afternoon hours, between 2:00 p.m. and 4:00 p.m., that also increased with the temperature. The differences observed in the ultrafine particle distribution and temporal trends clearly demonstrated that mechanisms other than direct emissions play an important role in the formation of ultrafine particles in receptor sites of the Los Angeles Basin. [Description provided by NIOSH]
• Subjects:
  Aerosols Environmental Monitoring Occupational Health Particulate Matter Safety Temperature
• Keywords:
  Air Monitoring Automotive Emissions Particle Aerodynamics Particle Size Seasonal Factors Temperature Effects Ultrafine Particulates
• ISSN:
  1096-2247
• 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:
  297-307
• Volume:
  52
• Issue:
  3
• NIOSHTIC Number:
  nn:20057894
• Citation:
  J Air Waste Manage Assoc 2002 Mar; 52(3):297-307
• Contact Point Address:
  Dr. Constantinos Sioutas, University of Southern California, Civil and Environmental Engineering, 3620 South Vermont Avenue, Los Angeles, CA 90089
• Email:
  sioutas@usc.edu
• Federal Fiscal Year:
  2002
• Performing Organization:
  University of California, School of Public Health, Los Angeles, CA
• Peer Reviewed:
  True
• Start Date:
  19990701
• Source Full Name:
  Journal of the Air and Waste Management Association
• End Date:
  20040630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:c953816770397d977034090cd8b8d432fb670b7fa1ea545efc9ee2087223d4fc3979a57ccb039ba9753f03c7a7cfe1f885bec9581012b4845ccacee2a9ad88d6
• Download URL:
  https://stacks.cdc.gov/view/cdc/215099/cdc_215099_DS1.pdf
• File Type:
  [PDF - 360.38 KB ]