2001 Progress Report: Characterization of the Chemical Composition of Atmospheric Ultrafine Particles

EPA Grant Number: R827354C001
Subproject: this is subproject number 001 , established and managed by the Center Director under grant R827354
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Airborne PM - Rochester PM Center
Center Director: Oberd√∂rster, G√ľnter
Title: Characterization of the Chemical Composition of Atmospheric Ultrafine Particles
Investigators: Cass, Glen , Prather, Kimberly A. , Dillner, Ann
Current Investigators: Cass, Glen , Prather, Kimberly A. , Hopke, Philip K. , Dillner, Ann
Institution: Georgia Institute of Technology , Arizona State University - Main Campus , University of California - Riverside
Current Institution: Georgia Institute of Technology , Arizona State University - Main Campus , Clarkson University , University of California - Riverside
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 identify the chemical composition of atmospheric ultrafine particle samples. Samples have been collected in field experiments in Houston, TX, seven cities in Southern CA (collectively referred to as Southern CA), and Riverside, CA. Three research groups, at the Georgia Institute of Technology (GIT), Arizona State University (ASU), and the University of California-San Diego (UCSD), are collaborating on this project.

Progress Summary:

The GIT/ASU group, led by Cass and Dillner, collected ultrafine particle samples in field experiments in Houston, TX, and in Riverside, CA, and automated equipment that measures ultrafine aerosol size distributions. Professor Cass participated in The Royal Society's (United Kingdom's National Academy of Science) Meeting entitled: "Ultrafine Particles in the Atmosphere" on March 15-16, 2000, which resulted in a published journal article. The UCSD group, led by Prather, is in the final stages of developing an aerosol time of flight (TOF) mass spectrometry instrument to measure the chemical composition of single atmospheric particles smaller than 100 namometers (nm) in particle diameter.

In August and September 2000, seven sets of 24-hour fine and ultrafine ambient samples were collected using cascade impactors at two sites in Houston, TX. The ultrafine concentration at the two sites ranged from 0.09 to 0.57 micrograms (µg)/m-3. The average composition of ultrafine aerosol did not significantly differ between the two sites and, as shown in Figure 1a, consisted of 40 percent organic compounds, 17 percent sulfate, 5 percent metal oxides, and trace amounts of elemental carbon, nitrate, ammonium, sodium, and chloride. The dominant transition metal ions, obtained by inductively coupled plasma-mass spectrometer (ICP-MS) analysis, were nickel, iron, and vanadium, with average concentrations less than 2 nanograms (ng)/m-3.

Analyses of data obtained at seven sites in Southern CA, showed average ultrafine particle concentrations ranging from 0.55 to 1.16 µg/m-3, and consisted of 50 percent organic compounds, 14 percent metal oxides, 8.7 percent elemental carbon, 8.2 percent sulfate, 6.8 percent nitrate, and traces of ammonium, sodium, and chloride (Figure 1b). The Houston ultrafine concentrations based on mass metrics were roughly half of those obtained in the Southern CA studies. Additionally, the ultrafine aerosol in Houston contained smaller percentages of organic compounds and metal oxides than Southern CA, but a larger percentage of sulfate. These results should assist researchers of the controlled clinical, animal, and in vitro studies of the University of Rochester–Environmental Protection Agency Partiuclate Matter Center in the design of realistic exposure studies involving ultrafine particles.

Figure 1. Speciation of Ultrafine Aerosol in (a) Houston, and (b) Seven Southern CA Cities.

In June and July 2001, ultrafine and fine aerosol mass samples and ultrafine and fine number size distributions were collected over five consecutive 24-hour periods in Riverside, CA. Ultrafine aerosol mass was collected by a nano-micro-orifice impactor (nano-MOI), which allows for size segregation of the aerosol into four bins below 0.1 µm (0.01 to 0.018 µm, 0.018 to 0.032 µm, 0.032 to 0.056 µm, and 0.056 to 0.1 µm). Analysis of impactor substrates for both ultrafine and fine (0.1 to 1.8 µm) aerosol is underway to determine the chemical composition of the aerosol. A nano-differential mobility analyzer (nano-DMA), and an ultrafine condensation particle counter (CPC), as well as a standard DMA and CPC were automated and used to obtain particle concentration as a function of size for particle diameters between 0.003 µm and 0.600 µm in the Riverside, CA, study.

An ultrafine particle aerosol TOF mass spectrometry instrument has been constructed. The aerodynamic lens system, which allows transmission of ultrafine particles into the instrument, has been successfully designed and installed. An effective method for detecting ultrafine particles in the system is being developed. Further studies will be undertaken to assess the chemical characterization capabilities of the instrument.

Meanwhile, ambient ultrafine particle measurements also have begun in Rochester, NY, and in Erfurt, Germany. In Erfurt, the elemental composition has been measured, measurement of organic composition has been started, and a device similar to particle aerosol TOF mass spectrometer is under development at the German National Research Center for Environment and Health (GSF).

Future Activities:

In spring 2002, aerosol characterization experiments will be undertaken in Rochester, NY, using two nano-micro-orfice uniform deposit impactors (MOUDIs) and ultrafine size distribution instrumentation, along with the ultrafine single particle aerosol TOF, mass spectrometry instrument. Comparison of bulk and single particle chemical composition data for Rochester will further enhance our understanding of the ambient ultrafine particles. Additional studies will be undertaken to characterize the ultrafine aerosol concentrator utilized in the animal studies performed by Rochester PM Center researchers. This characterization will provide a better understanding of the size and chemical composition of the ultrafine particles used in the exposure studies. Another planned study will be to characterize ambient ultrafine aerosol at a traffic-dominated site in the Los Angeles region.

Journal Articles:

No journal articles submitted with this report: View all 30 publications for this subproject

Supplemental Keywords:

Houston, Texas, TX, Riverside, California, CA, Rochester, New York, NY, ultrafine, aerosol, particulate matter, atmosphere, mass spectrometry., RFA, Health, Scientific Discipline, Air, Geographic Area, particulate matter, Environmental Chemistry, Health Risk Assessment, Epidemiology, State, Risk Assessments, Biochemistry, ambient air quality, particle size, particulates, sensitive populations, cardiopulmonary responses, chemical characteristics, fine particles, human health effects, morbidity, ambient air monitoring, pulmonary disease, susceptible populations, epidemelogy, particle exposure, environmental health effects, nano differential mobility analyzer, human exposure, chemical kinetics, particulate exposure, Texas (TX), PM, mortality, urban environment, aerosols, chemical speciation sampling, human health risk

Progress and Final Reports:

Original Abstract
  • 1999 Progress Report
  • 2000 Progress Report
  • 2002 Progress Report
  • 2003 Progress Report
  • 2004 Progress Report
  • Final Report

  • Main Center Abstract and Reports:

    R827354    Airborne PM - Rochester PM Center

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827354C001 Characterization of the Chemical Composition of Atmospheric Ultrafine Particles
    R827354C002 Inflammatory Responses and Cardiovascular Risk Factors in Susceptible Populations
    R827354C003 Clinical Studies of Ultrafine Particle Exposure in Susceptible Human Subjects
    R827354C004 Animal Models: Dosimetry, and Pulmonary and Cardiovascular Events
    R827354C005 Ultrafine Particle Cell Interactions: Molecular Mechanisms Leading to Altered Gene Expression
    R827354C006 Development of an Electrodynamic Quadrupole Aerosol Concentrator
    R827354C007 Kinetics of Clearance and Relocation of Insoluble Ultrafine Iridium Particles From the Rat Lung Epithelium to Extrapulmonary Organs and Tissues (Pilot Project)
    R827354C008 Ultrafine Oil Aerosol Generation for Inhalation Studies