The emissions characterization study is being performed in conjunction with the Pittsburgh Air Quality Study [PDF-744KB], a larger effort that includes ambient measurements and atmospheric modeling of the Pittsburgh region.

The main objectives of this portion of the study are:

• To achieve advanced characterization of the PM in the Pittsburgh region. Measurements include the PM size, surface, volume, and mass distribution; chemical composition as a function of size and on a single particle basis; temporal and spatial variability.
• To obtain accurate current fingerprints of the major primary PM sources in the Pittsburgh region using traditional filter-based sampling and state-of-the-art techniques such as dilution sampling and single particle analysis using mass spectroscopy and LIBS.
• To estimate the impact of the various sources (transportation, power plants, natural, etc.) on the PM concentrations in the area using both statistical and deterministic models.
• To quantify the responses of the PM characteristics to changes in these emissions in support of the emission control decision making in the area (SIP development, etc.)
• To develop and evaluate current and next generation aerosol monitoring techniques for both regulatory applications and for determining of source-receptor relationships.

Source Characterization

Emissions and Activity Survey
A survey of existing emissions information for the sources of primary PM and PM precursors will be conducted for the Pittsburgh region. Emissions of criteria pollutants from many of these sources are collected as part of the current EPA regulations. The existing source fingerprints for these source categories will be reviewed with respect to their applicability to the Pittsburgh area. An output of this survey will be the important source categories and a list of critical sources with limited profile data.

Activity data for all source categories will be collected throughout the sampling period with particular emphasis on the intensive sampling periods. Activity data for the major point sources is collected as part of the normal operations of the Allegheny County Department of Health Collects. PennDOT already has compiled average vehicle activity data on a monthly, daily, and hourly basis. We will collect activity data for important non-regulated sources such as wood combustion and meat cooking.

Source Sampling
Three different types of sources will be sampled in the Pittsburgh region: major point sources, mobile sources, and dust. Five major point sources tentatively selected for detailed sampling in the Pittsburgh area include two coal-fired boilers (one with low NOx burners), a coke plant, a steel mill, and an industrial manufacturing facility. The exact set of sources will be defined by the results of the emissions survey and access. More limited sampling may be performed on additional facilities depending on the results of the emissions survey. Mobile source emissions will be characterized by conducting a tunnel study. Dust samples will be collected and analyzed from various locations around western Pennsylvania.

For each source a variety of measurements are planned including standard filter based characterization, size-resolved measurements, and single particle measurements. The goal of these measurements is to develop accurate source fingerprints and emissions for source-receptor and deterministic modeling. The exact list of measurements will depend on plant access, access to a suitable sampling port, electrical power readily available, and provisions for placing equipment on the stack sampling platform - preferably this will be an elevator. The exact list of measurements will also depend on the decisions of the Pittsburgh Air Quality Study science team.

At appropriate sources we plan to collect integrated filter samples of PM2.5 to determine standard source profiles and, where applicable, mass emission rates. The filter samples will be analyzed for ionic species (e.g., nitrate, sulfate, ammonium), OC/EC, and trace metals using the previously described equipment. Florida International University (Rogge group) will perform detailed organic speciation of source samples as part of their work on the Pittsburgh Air Quality Study.

At appropriate sources we will perform an extensive suite of size-resolved measurements. Using the ultrafine SMPS, the regular SMPS, and the APS system, we will measure size distributions from 3 mm to 10 mm. Size-resolved mass and composition distributions will be measured using the MOUDI. MOUDI samples will be analyzed for major ions, trace elements, and OC/EC.

At appropriate sources single particle measurements will be performed using the RSMS-II single particle mass spectrometer, LIBS, and CCSEM to create a database of single particle fingerprints. The smog chamber in the Air Quality Laboratories at CMU could be used, if necessary, for the transfer of particles to the RSMS-II.

Fence line monitoring: For sources such as steel mills and coke plants that do not have a single well defined emissions point, fence line monitoring will performed to try to develop an integrated fingerprint for the source. This fence line monitoring will use semi-continuous measurement techniques, which hopefully will provide time resolution required to define accurate source fingerprints. We plan to use the semi-continuous OC-EC analyzer of Turpin and the semi-continuous metals technique of University of Maryland (Ondov group). The high temporal resolution of these instruments in conjunction with meteorology data should allow the measurement of adequate source profiles in this situation.

Combustion sources: Source profiles and emission rates on an energy basis will be measured for combustion sources such as coal-boilers. We plan to use a state-of-the-art dilution sampler to characterize emission from combustion systems and other high temperature sources. The sampler is constructed out of stainless steel and Teflon to minimize sample contamination. The dilution sampler enables the use of advanced aerosol characterization instrumentation such as a single particle mass spectrometer and sophisticated sampling trains to characterize the emissions.

We plan to collect samples with standard source sample trains such as the EPA method 5. Comparison of these standard measurements with samples collected with the dilution tunnel will provide valuable new information regarding the effects of dilution and sampling on source profiles and emission rates.

Tunnel sampling: An integrated fingerprint for the vehicles operating the Pittsburgh region will be determined using a full suite of measurements (filter-based, continuous, single particle, etc.) made in one of the Pittsburgh area tunnels. The emission rates for the measured components will be determined per unit fuel consumed, calculated using a carbon balance. The background concentrations needed to calculate the emission rates will be measured as part of the ambient study. Data on traffic density, composition, and speed through the tunnel will be obtained in collaboration with the Pennsylvania Department of Transportation (PennDOT). The tunnel sampling will require access to one of the tunnels in the Pittsburgh region.

Dust Sampling: Dust samples will be obtained from paved roads and soil in Western Pennsylvania, and size-resolved composition (e.g., PM2.5, PM10, PMx) will be measured using both filter and impactor based approaches and single particle mass spectrometry.