2002 Progress Report: Particle Size Distributions of Polycyclic Aromatic Hydrocarbons in the LAB

EPA Grant Number: R827352C013
Subproject: this is subproject number 013 , established and managed by the Center Director under grant R827352
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Southern California Particle Center and Supersite
Center Director: Froines, John R.
Title: Particle Size Distributions of Polycyclic Aromatic Hydrocarbons in the LAB
Investigators: Miguel, Antonio , Cho, Arthur K. , Froines, John R. , Sioutas, Constantinos
Current Investigators: Miguel, Antonio , Eiguren-Fernandez, Arantza , Sioutas, Constantinos
Institution: University of California - Los Angeles , University of Southern California , Michigan State University , University of California - Irvine
Current Institution: University of California - Los Angeles , University of Southern California
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 31, 2005 (Extended to May 31, 2006)
Project Period Covered by this Report: June 1, 2001 through May 31, 2002
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air


The objective of this research project is to focus on the central hypothesis of the Southern California Particle Center and Supersite, which is that organic constituents associated with particulate matter—including quinones, other organic compounds (polycyclic aromatic hydrocarbons [PAHs], nitro-PAHs, and aldehydes/ketones), and metals—are capable of generating reactive oxygen species and acting as electrophilic agents. They have a central role in allergic airway disease such as asthma and cardiovascular effects through their ability to generate oxidative stress, inflammation, and immunomodulating effects in the lungs and airways.

The specific objective of this research project is to extend our current knowledge of the size distribution of atmospheric PAHs present near freeways—located in the Los Angeles Basin and at an urban site—down to 10 nm aerodynamic diameter.

Progress Summary:

Measurement of the particle size distributions of 12 priority pollutant PAHs, elemental carbon (EC), organic carbon (OC), sulfate (SO4-2), and nitrate (NO3-) size distributions were made from October 2001 to July 2002, in Claremont, CA, a receptor site located about 40 km downwind of central Los Angeles. Samples were collected approximately once every week for 24-hour periods, and were composited for analysis into monthly periods in three aerodynamic diameter size intervals: 0-0.18 m (ultrafine mode); 0.18-2.5 m (accumulation mode); and 2.5-10 m (coarse mode). For the monthly composites from October to February, the size distributions of the target PAHs are similar. From March to July, however, notable differences are observed: a significant fraction of the PAH mass is found in the coarse mode as compared with the previous period. During the entire 1-year period, the form and shape of the EC size distributions did not vary much and are distinguished by prominent mass in the ultrafine and accumulation size mode. For the individual modes of the major species, the highest Pearson correlation coefficients for the variation of temperature with species concentration were found in the ultrafine mode for both SO4-2 (0.92) and EC (0.90), and in the coarse mode for both OC (0.85) and NO3- (0.54). High SO4-2 correlations are consistent with increased gas-to-particle formation during the warmer months from SO2 emissions in the Los Angeles seaport area and, similarly for EC, increased atmospheric transport to Claremont as the season progresses from winter to summer. Although the correlations were all positive for the group of more volatile PAHs (log [p°L] qreater than or equal to - 2.06), but were not statistically significant, they were all negative for the less volatile or particle-phase group (log [p°L] less than or equal to - 3.22), consistent with increased partitioning from the vapor phase with decreasing temperature. Size-resolved samples currently are being collected in Long Beach, central Los Angeles (University of Southern California), Upland, and Riverside.

Future Activities:

We will measure the size distributions of PAHs and PAH-quinones down to 10 nm in diameter in source and receptor areas of the Los Angeles Basin. Size distribution measurements will help our understanding of their formation mechanisms and their dependence on distance from freeways, and will allow an estimation of their deposition in the human respiratory system and atmospheric residence time. In addition, these data also may help in the design of effective control strategies for reducing PAH and PAH-quinone emissions to the atmosphere.

Journal Articles:

No journal articles submitted with this report: View all 14 publications for this subproject

Supplemental Keywords:

particulate matter, particle size distribution, PAHs, elemental carbon, organic carbon, sulfate, nitrate, air quality monitoring, human health risk, mobile source emissions, atmospheric transport, California, freeway study,, RFA, Scientific Discipline, Air, Geographic Area, HUMAN HEALTH, particulate matter, Environmental Chemistry, Health Risk Assessment, Air Pollutants, State, mobile sources, Health Effects, Environmental Monitoring, engine exhaust, ambient aerosol, asthma, motor vehicle emissions, epidemiology, human health effects, automotive emissions, particulate emissions, automobiles, automotive exhaust, air pollution, children, human exposure, diesel exhaust particles, PM characteristics, California (CA), allergens, indoor air quality, aerosols, atmospheric chemistry

Relevant Websites:

http://www.scpcs.ucla.edu/ exit EPA

Progress and Final Reports:

Original Abstract
  • 1999
  • 2000
  • 2001
  • 2003 Progress Report
  • 2004 Progress Report
  • Final Report

  • Main Center Abstract and Reports:

    R827352    Southern California Particle Center and Supersite

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827352C001 The Chemical Toxicology of Particulate Matter
    R827352C002 Pro-inflammatory and the Pro-oxidative Effects of Diesel Exhaust Particulate in Vivo and in Vitro
    R827352C003 Measurement of the “Effective” Surface Area of Ultrafine and Accumulation Mode PM (Pilot Project)
    R827352C004 Effect of Exposure to Freeways with Heavy Diesel Traffic and Gasoline Traffic on Asthma Mouse Model
    R827352C005 Effects of Exposure to Fine and Ultrafine Concentrated Ambient Particles near a Heavily Trafficked Freeway in Geriatric Rats (Pilot Project)
    R827352C006 Relationship Between Ultrafine Particle Size Distribution and Distance From Highways
    R827352C007 Exposure to Vehicular Pollutants and Respiratory Health
    R827352C008 Traffic Density and Human Reproductive Health
    R827352C009 The Role of Quinones, Aldehydes, Polycyclic Aromatic Hydrocarbons, and other Atmospheric Transformation Products on Chronic Health Effects in Children
    R827352C010 Novel Method for Measurement of Acrolein in Aerosols
    R827352C011 Off-Line Sampling of Exhaled Nitric Oxide in Respiratory Health Surveys
    R827352C012 Controlled Human Exposure Studies with Concentrated PM
    R827352C013 Particle Size Distributions of Polycyclic Aromatic Hydrocarbons in the LAB
    R827352C014 Physical and Chemical Characteristics of PM in the LAB (Source Receptor Study)
    R827352C015 Exposure Assessment and Airshed Modeling Applications in Support of SCPC and CHS Projects
    R827352C016 Particle Dosimetry
    R827352C017 Conduct Research and Monitoring That Contributes to a Better Understanding of the Measurement, Sources, Size Distribution, Chemical Composition, Physical State, Spatial and Temporal Variability, and Health Effects of Suspended PM in the Los Angeles Basin (LAB)