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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Elucidating the Role of Transition Metals, Organic Species, and Atmospheric Processing in Oxidant Production from Laboratory and Ambient Particulate Matter

EPA Grant Number: FP917181
Title: Elucidating the Role of Transition Metals, Organic Species, and Atmospheric Processing in Oxidant Production from Laboratory and Ambient Particulate Matter
Investigators: Charrier, Jessica Grace
Institution: University of California - Davis
EPA Project Officer: Just, Theodore J.
Project Period: September 1, 2010 through August 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010)
Research Category: Academic Fellowships , Fellowship - Clean Air

Description:

Objective:

Inhalation of ambient particulate pollution is known to cause morbidity and mortality in humans. One likely mechanism of toxicity is the production of oxidants in the lungs by the particles, which has been shown to cause inflammation and disease. The objective of my research is to elucidate the chemical species, sources, and atmospheric processes that affect oxidant production in the lungs from ambient particulate matter (PM).

Synopsis:

Inhalation of particulate matter can cause adverse health effects and mortality in humans. One mechanism of toxicity is production of oxidants in the lungs, which can lead to inflammation and disease. My project will investigate the detailed chemistry of oxidant production from particulate matter and its components. The results of this research will provide insight in the chemical components, sources, and atmospheric processes that cause particles to be most harmful to human health.

Approach:

My research will quantify production of two oxidants, hydroxyl radical and hydrogen peroxide, from laboratory and ambient particulate matter PM in cell-free surrogate lung fluid. The research will consist of four stages: 1) quantifying oxidant production from laboratory particles containing individual and mixed transition metals, 2) evaluating oxidant production from PM collected directly from various sources (e.g., diesel from dynamometer studies), 3) understanding the effect of atmospheric aging and secondary organic aerosol on oxidant production from both particle types in 1 and 2 by artificially aging the particle in the laboratory, and 4) applying this knowledge to ambient PM2.5 collected at sites with different source impacts.

Expected Results:

Previous work in my lab shows strong evidence that oxidant production is related to the transition metal content of ambient PM, especially iron and copper, and is dependent on the presence of ascorbate (or some other electron donor). I expected oxidant production from particles to primarily depend on the availability of soluble transition metals. Artificial aging of particles with ozone and light has been show to oxidize the surface of the particles, which may affect metal solubility and oxidant production. The addition of organics may affect oxidant production through multiple mechanisms: organics act as metal ligands, which can increase or decrease the reactivity of the metals; organics may act as electron donors increasing oxidant production from metals; or organics may be redox active and produce oxidants themselves. The organic content of the particles may strongly affect oxidant production in some cases.

Potential to Further Environmental/Human Health Protection:

The results of my research will provide insight in the chemical components, sources, and atmospheric processes that cause PM to produce high concentrations of oxidants, providing the necessary information to enact effective policy for protection of human health. Along with an understanding of the detailed chemistry, the method I will use allows for quantitative determination of hydroxyl radical and hydrogen peroxide, which provides dose estimates necessary to better understand health effects.

Supplemental Keywords:

oxidative stress, reactive oxygen species, hydroxyl radical, hydrogen peroxide, health, particulate matter, air pollution,

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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