Grantee Research Project Results
2008 Progress Report: Toxicological Evaluation of Realistic Emission Source Aerosol (TERESA): Investigation of Vehicular Emissions
EPA Grant Number: R832416C005Subproject: this is subproject number 005 , established and managed by the Center Director under grant R832416
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Health Effects Institute (2015 - 2020)
Center Director: Greenbaum, Daniel S.
Title: Toxicological Evaluation of Realistic Emission Source Aerosol (TERESA): Investigation of Vehicular Emissions
Investigators: Koutrakis, Petros , Godleski, John J. , Wolfson, Jack M. , Lawrence, Joy
Current Investigators: Koutrakis, Petros , Godleski, John J.
Institution: Harvard University
EPA Project Officer: Chung, Serena
Project Period: October 1, 2005 through September 30, 2010 (Extended to September 30, 2011)
Project Period Covered by this Report: July 1, 2007 through June 30,2008
RFA: Particulate Matter Research Centers (2004) RFA Text | Recipients Lists
Research Category: Human Health , Air
Objective:
Because particulate and gaseous source emissions undergo many transformations once released into the atmosphere, it is likely that secondary and primary pollutants exhibit different toxicities. Since most of the source-specific toxicity studies to date have focused on primary pollutants, there remains a great need to investigate the relative toxicity of source-specific primary and secondary particles. We have recently probed directly into this question with the Toxicological Evaluation of Realistic Emission Source Aerosol (TERESA) Power Plant study, a research project funded by the Electric Power Research Institute (EPRI) and the previous Harvard EPA PM Center. This study was designed to investigate the relative toxicity of primary and secondary particulate emissions from coal-fired power plants, in situ, and to explore the relationship between secondary particle formation processes and particle toxicity. As part of the TERESA study we have developed techniques and facilities to sample source emissions, form secondary particles inside a photochemical chamber, and expose animals to both primary and secondary particles. The TERESA approach forms an excellent foundation for future research, as it can readily be adapted to investigate other combustion sources. Using the developed technologies, this project extends this research to the toxicological investigation of primary and secondary pollutants from vehicular (mobile source) emissions released from the ventilation stack of a large roadway tunnel within the northeastern United States. We are in the preparation stages for this project that will compare the relative toxicity of primary and secondary mobile source emissions with concentrated ambient particles (CAPs) and with primary and secondary coal power plant emissions from the current TERESA study.
The specific hypotheses of this project:
- Exposures to fresh and to photochemically oxidized mobile source emissions will induce cardiovascular responses in normal animals;
- Atmospheric photochemical processes enhance the toxicity of gases and particles emitted from motor vehicles, and;
- Animal models of susceptible populations (e.g., spontaneously hypertensive rats) will have greater biological responses to particles originating from motor vehicles than the corresponding normal animal model.
Progress Summary:
Permission to use an urban tunnel to provide mobile source emissions:
The original plans for TERESA experiments, starting with funding from EPRI, and then expanded with funds from both DOE and the first Harvard EPA PM Center, included the goals of comparing the health outcomes from both stack gas from coal-fired power plants and from mobile sources with health outcomes from concentrated ambient particles (CAPs). After the power plant studies were initiated, we had discussions with the original TERESA scientific advisory committee about the best way to conduct the mobile source experiments. We quickly concluded that to get meaningful results it would be necessary to use actual traffic emissions rather than controlled emissions from lab tests using a dynamometer with only one or a few vehicles. To get the most representative mixtures of actual vehicle emissions, and to maximize the emission concentrations, we decided that traffic tunnels would be the optimum sources.
We made initial contacts to local agencies responsible for urban tunnels not long after we first began the TERESA project. We quickly concluded that the ideal sampling location should be at one of the ventilation shafts for the tunnels. We have had a long series of considerations to identify an appropriate site and obtain permission for use. This process has taken more than two years. However, we now have been given approval for use of an urban site which we will further characterize in terms of traffic mix and traffic emissions.
Preliminary laboratory chamber tests for simulation of secondary particle formation from mobile source emissions:
Based on the experience and knowledge gained from the power plant studies, we were prepared to make the adaptations necessary to convert our mobile laboratory reaction chamber from the requirements for producing secondary particles from power plant stack gas to the requirements for producing secondary particles from mobile source emissions. The fundamental chemistry for power plant stack gas that is relevant to the TERESA studies is the oxidation of SO2 to form acidic sulfate aerosol. Hydroxyl radical is used for the oxidation, and it is produced by high energy UV irradiation of ozone. Because ozone reacts most rapidly with NO present in the stack gas, excess ozone has to be added to have enough to use to produce hydroxyl radical. In addition, because the stack gas is diluted with dry air, and because water vapor is necessary to promote the oxidation chemistry, humidity of the reaction chamber is added using a small steam generator. For the mobile source emissions, the relevant reactions involve oxidation of volatile organic species (VOC’s) by hydroxyl radicals (and ozone), in the presence of medium energy UV light (similar to natural sunlight). Unlike the power plant stack gas, excess ozone does not need to be added to titrate NO that is present in mobile vehicle exhaust gas; ozone concentrations increase rapidly in the chamber once the lights are turned on. Water vapor must also be added to promote the oxidation of VOC’s. The primary difference in the reaction chamber requirements for mobile source emission secondary particle production is the use of lower energy UV lamps.
We have started preliminary laboratory tests for mobile source emissions using the same chamber that was used for the power plant study. We use lower energy UV lamps. A ten-year old compact automobile is used as a source of emissions. The engine is run slightly fuel-rich during experiments, causing inefficient fuel combustion and resulting in CO concentrations similar to those observed in the highway tunnel. With the engine of the car idling, we expect that the CO concentration is a reasonable surrogate for VOC’s. By diluting the exhaust gas to produce different known CO concentrations, we are thus able to control the VOC concentrations in the chamber and produce enough secondary aerosols to be in the range of concentrations needed for animal exposure tests. Our laboratory development tests will also involve variation in the flow rate through the chamber, to determine the effects of residence time on particle mass formation and particle size distribution. We also plan to test the effect of different concentrations of water vapor. Finally, the parallel plate membrane denuder, used in the TERESA power plant study to minimize concentrations of gaseous co-pollutants in the exposure atmospheres, will be evaluated for its efficiency in removing unreacted VOCs in the diluted and aged automobile exhaust mixture.
Future Activities:
Our goal is to complete laboratory tests by the end of this fall, and start field tests next winter. Keeping this schedule will depend on successful completion of the lab tests and formal approval from the Mass Turnpike Authority. The initial field tests will require optimizing the features of the reaction chamber to correspond to expected differences between the single vehicle exhaust used for lab tests and the mixed vehicle exhaust from the traffic tunnel. We expect it will take a few months to complete the optimization tests. Toxicological exposures to primary and secondary aerosols from vehicular emissions are expected to be completed before the end of year 4 of this Center.
Journal Articles:
No journal articles submitted with this report: View all 9 publications for this subprojectSupplemental Keywords:
ambient air particles, cardiovascular health, pulmonary health, air pollution, traffic emissions, traffic related particles, acute cardiovascular effects, primary and secondary particle effects;, RFA, Health, Scientific Discipline, Air, particulate matter, Toxicology, Environmental Chemistry, Health Risk Assessment, Risk Assessments, ambient air quality, atmospheric particulate matter, chemical characteristics, concentrated ambient particulates (CAPs), human health effects, airborne particulate matter, cardiovascular vulnerability, automobile exhaust, animal model, biological mechanisms, traffic related particulate matter, chemical composition, biological mechanism , ambient particle health effects, autonomic dysfunction, PM, oxidative stressRelevant Websites:
http://www.hsph.harvard.edu/epacenter/Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
R832416 Health Effects Institute (2015 - 2020) Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R832416C001 Cardiovascular Responses in the Normative Aging Study: Exploring the Pathways of Particle Toxicity
R832416C002 Cardiovascular Toxicity of Concentrated Ambient Fine, Ultrafine and Coarse Particles in Controlled Human Exposures
R832416C003 Assessing Toxicity of Local and Transported Particles Using Animal Models Exposed to CAPs
R832416C004 Cardiovascular Effects of Mobile Source Exposures: Effects of Particles and Gaseous Co-pollutants
R832416C005 Toxicological Evaluation of Realistic Emission Source Aerosol (TERESA): Investigation of Vehicular Emissions
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.
Project Research Results
9 journal articles for this subproject
Main Center: R832416
206 publications for this center
199 journal articles for this center