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2007 Progress Report: PM Characterization and Exposure Assessment (Project 2)
EPA Grant Number: R832417C002Subproject: this is subproject number 002 , established and managed by the Center Director under grant R832417
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Johns Hopkins Particulate Matter Research Center
Center Director: Samet, Jonathan M.
Title: PM Characterization and Exposure Assessment (Project 2)
Investigators: Geyh, Alison , Breysse, Patrick , Chillrud, Steven , Datta, Saugatta , Ondov, John M.
Current Investigators: Geyh, Alison , Breysse, Patrick
Institution: Johns Hopkins University , Columbia University (Lamont Doherty Earth Observatory) , Georgia College and State University , University of Maryland
Current Institution: Johns Hopkins University
EPA Project Officer: Stacey Katz/Gail Robarge,
Project Period: October 1, 2005 through September 30, 2010
Project Period Covered by this Report: October 1, 2006 through September 30, 2007
RFA: Particulate Matter Research Centers (2004)
Research Category: Particulate Matter
Description:
Objective:The focus of Project 2 is the measurement of specific chemical components and physical characteristics of PM from different areas of the country in support of the Center focus, which is assessing characteristics of PM that determine toxicity. The goals of Project 2 are to collect bulk PM samples for use in biological assays and for detailed characterization including mass, inorganic ions, elemental carbon and organic compounds, specifically polycyclic aromatic hydrocarbons , elemental metals and their oxides, and sulfur isotope ratios. We will also collect information on particle size. The objectives of Project 2 include: 1) the development of methods for collecting bulk ambient PM, and a system for characterizing the chemical and physical properties of ambient PM; 2) the identification of specific regional differences in PM characteristics that may contribute to differential biological responses demonstrated by in vitro and in vivo bioassay systems; 3) the assessment of a relationship between human exposure to PM2.5 and biological response during a high PM2.5 exposure period and a low PM2.5 exposure periods. The goals and objectives have remained unchanged over this time period.
Progress Summary:- Introduction
The rationale for this project is based on the conclusion that “[t]he diversity of PM characteristics and the array of possible health effects define a potentially large and complex matrix for investigation; in fact different features of particles might be relevant to different health outcomes” (NRC 2004) As a result we proposed to assess the specific chemical components and physical characteristics of particulate matter (PM) from samples taken in different areas of the country. These locations have been selected based on a gradient of estimated risks to health. Specifically, we proposed to develop a new method for collecting bulk PM for use in biological assays; to develop a portable system for the characterization of chemical and physical properties of ambient PM; and to identify specific regional differences in PM characteristics that may contribute to differential biological responses in in vitro and in vivo bioassay systems. We have completed the first two aims and are in the beginning stages of the third aim.
- Development of the Hopkins Sequential Cyclone Sampler (HSCS)
Table 1. Summary of performance characteristics for proposed cyclone collection system.
Stage
Cut size
1
10 μm
2
2.5 μm
3
0.5 μm
The initial proposed design of the HSCS included a sequence of three cyclones that would allow collection of particles with three cut size ranges as described in Table 1. The first stage would collect particle greater than 10 mm; the second stage would collect particles greater than 2.5 mm providing a coarse fraction when operated in sequence with stage 1; and stage 3 would have a cut size of greater than 0.5 mm. When operated in series, this system would provide PM2.5 and coarse samples of bulk PM. A prototype version was manufactured and tested late last year. Initial testing of the stage 1 cyclone showed that a sharp 50% cut point for 10 mm particles could not be clearly defined at the desired flow rate. After an evaluation of the options available to us, we decided to use a commercially available high volume PM10 inlet (HI-Q Environmental, San Diego, CA) as stage 1. The stage 2 and 3 cyclones were retained.. The system is designed to operate at a flow rate of 1 m3/minute. Stages 2 and 3 have been tested and the system configuration finalized.
- PM Monitoring
Instrument Deployment: The feasibility of conducting ambient PM monitoring around the country by deploying the PM monitoring equipment in an 8’ x 24’ trailer was questioned by the SAC last year. Concerns were raised about the cost of and time need to provide power to the trailer, as well as the cost of transporting the trailer from location to location. Since refurbishment of the trailer was in process, Project 2 continued to explore the logistics of this approach. The results of this exploration are summarized below:
The Cost of Ground Power: The University was approached for assistance in setting up power to the trailer in the JHU parking lot where Project 2 had been give permission to park and set up the trailer. The University declined to assist. The local power company was contacted for a cost estimate. A contractor, Brown & Heim, was contacted for an estimate of cost to setup a connection from the main power supply on the parking lot to the trailer. This set up would include a step down transformer as well as permanent electrical poles and wiring to connect the transformer to the trailer. The total estimated cost to set up the infrastructure and power to the trailer in the JHU parking lot was $23,000, with a timeline of 3 months.
The Cost of Portable Power: The possibility of onboard power generation was explored. Innovative Energy Solutions was contacted to discuss generator options. A Kohler 20KW diesel Tier I generator which could run on low sulfur fuel was identified as potential candidate. The generator included a 55 gal tank. The cost of the generator was $25,000. If set to run for 24 hrs a day, the generator would need refueling every 2-3 days for an approximate fuel cost per site of $2250. A satisfactory option for dealing with the exhaust was not identified.
The Cost of Transport: A professional driver was strongly recommended to haul the 8’x 24’ trailer. Cost of hiring a driver for a one-way load was $5.00/mile. If no load could be identified for a return trip the cost of the driver was an additional $2.50/mile. Estimated cost of a one-way trip to CA - $15,000.
Conclusion: Based on the SAC’s advise and our own analysis, it was determined that the trailer approach was not feasible. An alternative approach has been developed. Equipment will be shipped by professional shippers (FedEx) to each location. Where feasible, Project 2 will set up equipment in a currently running air quality monitoring station. When that option is not possible Project 2 will shelter the equipment in a stand alone structure. The instrumentation has been reduced to the necessary equipment needed for characterizing ambient PM (Table 2). The challenges of this approach include finding a location willing to host us, and which has adequate power and good security.
Table 2. Summary of sampling equipment for characterizing PM.
Monitor
Analyte
TSI 3321 Aerodynamic Particle Sizer
PM between 0.5 – 20 um
TSI 3936 Scanning Mobility Particle Sizer
Series 3080 Electrostatic classifier
Series 3010 Condensation Particle CounterPM between 2.5 – 1000 nm
PM2.5 Harvard Impactors
PM2.5 um and below
R&P Co. Inc. 8400N Ambient Particle Nitrate Analyzer with a PM2.5 inlet
PM2.5 nitrate
Thermo Fisher Scientific 5020 Sulfate Particulate Analyzer with a PM2.5 inlet
PM2.5 sulfate
Magee Scientific Aethalometer
Black carbon
EcoChem PAH monitor PAS2000
Particle bound polycyclic aromatic hydrocarbons
Hopkins Sequential Cyclone System
Bulk samples PM10-PM2.5, PM2.5 – PM0.5
ESC 8816 Data Logger/ Agilaire E-DAS Digi-Trend softward
Acquire, process, store, and telemeter data collected by the 8400N, 5020SPA, PAS2000.
Monitoring locations: With the identification of the proposed monitoring locations by Project 1 in March 2007, the Project 2 team began the process of identifying specific sites within each county where monitoring would be conducted. King County WA and Sacramento CA were targeted as the first locations for monitoring site identification because Project 2 has contacts in both counties. Assistance has been requested from EPA in contacting local air quality agencies in counties where Project 2 has no current contacts. EPA has now sent on this letter.
Sacramento County, CA: Locations within Sacramento County as possible monitoring locations include a current air quality monitoring site or the UC Davis Medical Campus. With the assistance of Dr. Anthony Wexler, contacts were made with the California Air Resources Board (CARB), and the Sacramento Air Quality Management District (SMAQMD). The CARB, which is responsible for a monitoring site in Sacramento County, determined they could not accommodate either our requests; that of allowing us to set up within their current monitoring station, or to set up our own self-contained monitoring shelter. At the end of April, 2007, Dr. Geyh traveled to Davis and Sacramento CA to assess potential monitoring sites and to meet with Dr. Wexler and the SMAQMD. With the help of Dr. Wexler, UC Davis Medical Campus Facilities was approached for permission to setup the PM Center monitoring station in a large parking lot near the radiology facilities. UC Davis is currently indicating that it will not make the parking lot available. SMAQMD, which is responsible for 3 monitoring sites in the county, identified one site in the City of Folsom as potentially able to accommodate the PM Center monitoring station.King County, WA: Possible monitoring locations within King County were identified through a contact at the University of Washington, which provided us with names at the Puget Sound Clean Air Agency (PSCAA), and at the Air Quality Program (AQP) of the Department of Ecology. At the beginning of May 2007, Drs. Breysse and Rule flew to Seattle to meet with representatives from both organizations and visit sites for which they have responsibility. Verbal agreement was obtained from both officers to share space and resources to house our sampling needs. The PSCAA manager offered their Duwamish and Lake Forest sites. The Duwamish site has plenty of space, security and power to accommodate our sampling equipment, but is located in an industrial valley, surrounded by heavy industry such as a cement factory and a heavy truck highway and railroad are less than a mile away. The Lake Forest site is located on the roof of a shopping center, with very difficult access and little space. The AQP offered their Beacon Hill site, which is centrally located on top of a low hill surrounded by urban development and which has been identified by the local agencies to provide good representation of urban PM in the county. We have been communicating with this AQP officer to finalize details, and a tentative schedule has been proposed to start monitoring at the beginning of August.
Maricopa County, AZ: We have been provided with two names at the Arizona Department of Environmental Quality (ADEQ) and one name at the Maricopa Department of Environmental Quality (MDEQ). We have contacted the ADEQ.
Table 3. Proposed Monitoring Schedule
Monitoring
OrderCounty
Tentative Start Date
Tentative End Ddate
1
King, WA*
August 1, 2007
August 30, 2007
2
Sacramento CA*
October 1, 2007
October 30, 2007
3
Maricopa AZ
February 1, 2008
March 1, 2008
4
Harris TX
April 1, 2008
April 30, 2008
5
Orange FL
May 1, 2008
May 30, 2008
6
Kings NY
July 1, 2008
July 30, 2008
7
Hennepin MN
September 1, 2008
September 30, 2008
*Scheduled
At each location during the periods listed above the equipment listed in Table 2 will be deployed.
- PM Characterization
- ICP-MS Capability at JHSPH
In November 2006, the Department of Environmental Health Sciences acquired an Agilent 7500ce Inductively Coupled Plasma Mass Spectrometer (ICP-MS Agilent Technologies, Newark DE). The instrument is housed in the laboratories of Dr. Geyh and is now available for routine element analysis for all PM samples collected by Project 2. Sample preparation protocols have been established in collaboration with co-investigator Dr. Chillrud (LDEO – CU). A between-laboratory comparison of bulk PM collected on the roof of the Bloomberg School of Public Health for 29 metals is being conducted.
- Pt (platinum) Group Element Analysis and Future Work
Accomplishments and plans for work conducted at LDEO-CU: Steven Chillrud and James Ross
The long term goal of the work being done at Lamont Doherty Earth Observatory of Columbia University (LDEO-CU) is to provide additional characterization of the particulate matter samples being collected by the PM Center at various locations in the United States. Initially it had been proposed that routine analysis of PM samples collected by Project 2 for a suite of elements by HR-ICP-MS, would be conducted by LDEO-CU. However, since the Johns Hopkins team has their own ICP-MS, LDEO-CUis focusing efforts on establishing methods for additional trace markers that are more difficult to characterize, but have significant importance as source tracers. In particular, we have been testing methods for digesting and analyzing samples for platinum group elements. We have also been collaborating with co-investigator Dr. Saugata Datta at GCSU in efforts to optimize sampling collection, and post-sampling preservation issues for analysis of particulate matter samples for measuring the oxidation state and coordination number of a number of metals at the Brookhaven National Laboratory.
Platinum group elements (PGEs) are found at extremely low concentrations (<1 ppb) in geologic and building materials. Emissions from catalytic converters used on cars and trucks are the primary sources of contaminant PGEs found in the environment. Of particular interest in terms of source signatures is the fact that the mixture of three different platinum group elements (Platinum (Pt), Rhodium (Rh), and Palladium (Pd)) used in catalytic converters is reportedly different in trucks versus cars. Furthermore the composition of PGEs in catylictic converters has changed over the last 3 decades since their original introduction in the 1970s in the United States.
Platinum group elements are found in particles ranging from <1 micron to several microns in size. Thus, PGE’s potentially provide a unique tracer of the exposure to and transport of the larger size range of particulate traffic emissions, as well as transport of resuspended street dust. The time history, compositional changes, and acute allergenic response of some occupational workers to platinum have allowed speculations of a link between the time history of PGE use in catalytic converters and the increase in prevalence in asthma rates, although no additional supporting evidence exists as far as we are aware.
To date, we have tested a number of digestion methods. An aqua regia digest followed by cation column chemistry has been found to be the best of the methods tested to date. In addition, we have been working to reduce the mass of PM needed for reproducible results. Initial mass required for this analysis was 200 mg. We have been successful in reducing that to <2 mg. Testing on Standard Reference Material BCR-723 (tunnel dust) has suggested excellent results for platinum (Pt) with less reliable recoveries for Rhodium (Rh) and Palladium (Pd).
In the coming year, we plan to continue work on the PGE’s. In particular we want to further investigate and improve the method through the use of an isotopically enriched Pt spikes to assess recoveries in different steps of the sample preparation process, further investigate isobaric and matrix interferences, and determine whether corrections are possible (i.e., use high resolution mode of ICP-MS or monitor interfering analytes). We also plan to investigate other elements found in catalytic converters including: aluminum, cerium and zirconium. We then will analyze samples collected at the various field sites.
Future Work at LDEO-CU: We also plan to focus some of our effort on the analysis of trace organic compounds in airborne particulate matter. Dr. Beizhan Yan, an organic geochemist specializing in the analysis of trace organic compounds including PAHs and their compound-specific stable isotope ratios, will be working in Dr. Chillrud’s group starting September 2007. He will need a month to set up his lab. Dr. Yan’s contribution to the research being conducted by Project 2 will be the analysis and interpretation of results for PAHs within the bulk and filter based PM for determining relative contributions from different combustion sources. Dr. Yan is also interested in developing new methods for resolving specific compounds within the “unresolved complex mixture” of hydrocarbons related to fuel combustion.
- Oxidation States and Coordination Chemistry and Future Work
Accomplishments and plans for work conducted at the Brookhaven National Lab: Saugata Datta (GCSU) and Steve Chillrud (LDEO)
The long-term goal of the work being done at the Brookhaven National Lab is to characterize the oxidation state and coordination number of key metals in samples from locations that are identified by the larger project as having different types of PM related health outcomes. Both bioavailability and toxicity can be affected by the oxidadation state and coordination number of the metal. Initial work is focused on optimizing sampling collection, and post-sampling preservation issues for analysis on the synchrotron light source.
Work to date: Beamtime at Brookhaven National Lab was scheduled from March 22 – 29, 2007. During this time, standards for three elements of interest were assessed: Mn, Fe, Cr, Ni. Different support media were evaluated including scotch tape, kapton tape and quartz fiber filter material. Finally, two samples of airborne particulate matter (one on kapton tape and one on quartz filter) were analyzed. For Mn we employed both the Lytle and PIPS detectors. We ran two samples previously collected which had Mn concentrations in ppm range.
Evaluation of the support media included direct sample measurements on quartz filters (without transferring the particles to Kapton tape). Measurements on blank quartz filters indicated that the quartz filter absorbed about 30% of the signal beam strength. In comparison, naked Kapton tape showed about 30% absorbance, while naked scotch tape showed about 10%.
Evaluation of changes in oxidation state over time was also conducted. We re-ran three samples that had previously been run on a different beamline to test post sampling preservation issues. These three high volume samples collected from the NYC subway system were initially stored under N2 at -70 °C prior to being analyzed on a separate beamline a year ago. After these initial analyses, the samples were stored in ziploc plastic bags in ambient conditions until they were run on this beamline for Fe. The data were consistent with no major change as compared to earlier data on Fe in terms of relative composition of Fe II,III oxidation states. This suggests that at least for Fe no special preservation technique is necessary for airborne samples collected in the subway. However, we want to confirm these results for Cr and Mn, which are present in subway samples as well, but only in the ppm range.
Next Steps: Our next objective is to identify the oxidation and coordination states of Mn in size-segregated samples of airborne PM with the goal of an initial assessment of sampling and sample preservation issues. To optimize the number of comparisons that can be made in the coming cycles, we will initially focus only on Mn and Cr and collecting PM with % levels (coal ash, welders fumes, subway-highway-tunnels’ ambient dust). Air sampling equipment and media for initial use will be MOUDI impactor operating at 30 LPM, Anderson low pressure impactor (3 LPM), and/or a High volume sampler (1000 LPM) set up with a cascade impactor plates (Staplex, Brooklyn NY). The PM will be impacted onto different medium, including kapton tape and trace metal clean quartz filters. We propose to focus on two key size ranges- the coarse particles (>3 µm in diameter) and one of the accumulation mode size ranges (e.g., 0.5 – 1 µm). Samples will be stored at -70°C and under nitrogen after collection until analyzed and then stored under ambient conditions and re-analyzed at a later date.
After an optimized medium and collection method has been shown to work for Mn, we will use this method to collect and analyze PM collected by Project 2 from different locations across the country.- here we will also investigate whether measurements can be made on ambient PM for a wider suite of elements with potential health concerns (Fe, Mn, Ni, V, Cr, Se). For example Baltimore has local coal-fired plants and metal industries but little fuel oil used for space heating while NYC has little local coal combustion and major emissions from fuel oil combustion for space heating and diesel traffic). For example, in NYC in winter, ambient PM2.5 samples have the following mean elemental particle concentrations of PM2.5: Fe =7200 ppm, Ni = 1900 ppm, V = 600 ppm, Mn = 230 ppm, Cr (summer mean = 30 ppm) and Se (summer mean = 60 ppm). Since PM2.5 typically includes some crustal material (the tail of the crustal distribution is below 2.5 µm), anthropogenic elements related to combustion should be more enriched in the 0.5 – 1 µm size fraction.
Our long term goal is to characterize the oxidation state and coordination number of key metals in samples from location that are collected by the PM Center.
- ICP-MS Capability at JHSPH
Bulk particle collection, cyclone, exhaled breath condensate, markers of inflammation,
,
Air, Scientific Discipline, Health, RFA, PHYSICAL ASPECTS, Risk Assessments, Health Risk Assessment, Physical Processes, Epidemiology, particulate matter, cardiovascular disease, ultrafine particulate matter, particulate matter components, aersol particles, human health risk, acute cardiovascular effects, atmospheric particles, ambient particle health effects, airway disease, atmospheric particulate matter, exposure, long term exposure, atmospheric aerosol particles
Progress and Final Reports:
2006 Progress Report
Original Abstract
2008 Progress Report
Main Center Abstract and Reports:
R832417 Johns Hopkins Particulate Matter Research Center
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R832417C001 Estimation of the Risks to Human Health of PM and PM Components
R832417C002 PM Characterization and Exposure Assessment (Project 2)
R832417C003 Biological Assessment of the Toxicity of PM and PM Components