Measurement and Toxicological Assessment of Population Exposures to Airborne Particulate Matter (PM) in Subways and Light Rail Trains

Expansion and increased use of urban public mass transit systems in the future are often portrayed as an unalloyed good with multiple personal, societal and environmental benefits. However, there is increasing evidence that respirable particulate matter (PM) in public mass transit systems is different from urban ambient PM concentrations. PM mass concentrations in urban subway systems have been reported to be up to an order of magnitude higher than at above-ground companion sites. Further, concentrations of metals (particularly iron, and other transition metals such as manganese, chromium and nickel) can be present in concentrations up to 100 times greater than typically observed in urban air dominated by motor vehicle emissions. Not only may these species be toxic by themselves, but chemical interactions may increase oxidative stress within the cell. The association between elevated PM concentrations and adverse human health effects is well-established. While all of the specific mechanisms of impact remain to be determined, there is substantial evidence that induced oxidative stress is the principal factor in some health outcomes. The primary objective of this project is to make measurements in the Los Angeles Metro system in order to quantify the chemical composition and physical and toxicological properties of respirable PM concentrations in its subway and light rail system. Observations in other systems may or may not be directly extrapolated to Los Angeles, although they do provide guidance. No systematic observations have previously been made in the Los Angeles transport system whose ridership has increased over 15% in the last two years and is expected to increase further in the future.


  • English


  • Status: Completed
  • Funding: $90000.00
  • Contract Numbers:


  • Sponsor Organizations:

    National Center for Metropolitan Transportation Research

    University of Southern California
    650 Childs Way, RGL 107
    Los Angeles, CA  United States  90089-0626
  • Project Managers:

    Valentine, Victoria

  • Performing Organizations:

    University of Southern California, Los Angeles

    University Park Campus
    Los Angeles, CA  United States  90089
  • Principal Investigators:

    Ning, Zhi

    Sioutas, Constantinos

  • Start Date: 20101001
  • Expected Completion Date: 0
  • Actual Completion Date: 20110930
  • Source Data: RiP Project 26520

Subject/Index Terms

Filing Info

  • Accession Number: 01461410
  • Record Type: Research project
  • Source Agency: National Center for Metropolitan Transportation Research
  • Contract Numbers: 10-07
  • Files: UTC, RIP
  • Created Date: Jan 3 2013 1:45PM