Impact/Purpose:

To conduct research on existing and proposed methods for determining PM mass concentrations under a variety of weather conditions and aerosol types and concentrations. As necessary, to develop methods or design specifications for PM mass determination in support of NAAQS development and implementation.

Description:

This task supports research into methodologies for determining particulate matter (PM) mass concentrations. Due to the complexity of PM (composition, size distribution, and concentration), developing PM methods that perform acceptably under most weather conditions at most U.S. locations remains a challenge. Methods that work acceptably at some locations or seasons fail at other locations or seasons, creating a fundamental problem in designating a nationally applicable Federal Equivalent Method (FEM) for PM. Continued research to evaluate methods developed by vendors is warranted. In some cases, this task may sponsor or conduct development of methods or design specifications that will lead to acceptable solutions.

Continued investigation of PMcoarse methods will be the major effort during FY05-06 (i.e., leading to promulgation of the new PMcoarse standard). Work will also focus on PM2.5 continuous methods as the Agency considers revisions to the equivalency requirements for PM2.5 to include Class III monitoring methods.

Record Details:

Record Type:PROJECT

Start Date:10/01/2005

Projected Completion Date:09/01/2008

OMB Category:Other

Record ID: 84588

Show Additional Record Data

Project Information:

Progress :Effective in FY05, this project will transfer from Subtask 1 of Task 12187. Research to support the 2005 promulgation of a PMcoarse standard is covered under the old task/subtask. Further research will be covered under this task.

In response to EPA's decision to develop and promulgate a new NAAQS for the coarse fraction of PM10, a program was established to compare the field performance of existing PMc samplers, develop data quality objectives for PMc measurements, draft a reference method for PMc sampling, and to develop testing methodologies and acceptance criteria for equivalent PMc monitoring methods. Based on the need to measure ambient PMc mass concentrations relative to aerodynamic diameter, a survey was conducted of commercially available and prototype PMc monitors. As a result of this survey, five separate PMc monitoring approaches were selected for subsequent evaluation. In order to address multiple monitoring objectives, continuous as well as integrated samplers were evaluated. Multiple samplers of each type were obtained from the respective manufacturers and SOPs were developed for their setup, use, and data retrieval. Following 15 days of shakedown tests in RTP, the respective performance of each sampler type was evaluated during four comprehensive field campaigns conducted at three separate sampling sites - Gary, IN, Phoenix, AZ, and Riverside, CA. The instrument manufacturers were involved in all phases of the field evaluations to ensure that the resulting data was valid and was properly interpreted.

Because there do not exist standards for atmospheric aerosol concentrations, a difference method of designated FRM samplers (i.e. PM10 - PM2.5) approach was selected to compare the relative accuracy of candidate PMc sampling methods. Results from the field campaigns showed that the inter-manufacturer precision among the integrated samplers was typically excellent. The relative accuracy of the samplers varies as a function of site and season but ranged from acceptable (within 10%) to as much as 50% in error. Correlation between the candidate samplers and the difference method samplers was typically excellent as expressed by coefficients of determination which averaged greater than 0.95.

The results of the field campaigns and the subsequent data analysis were summarized in a written report and submitted to the CASAC Ambient Air Monitoring Methods Subcommittee for review. At the request of the Subcommittee, the validated data sets from each field study were compiled and submitted to each committee member for review. In written comments submitted to the Agency, the Subcommittee expressed a consensus that the study design was well conceived and that the difference method provided the most fundamental basis of comparison upon which to evaluate candidate PMc samplers. The Subcommittee also recognized that noted performance issues with the candidate samplers needed to be addressed and that subsequent field evaluations of second generation instruments would be required.

ORD has been working with the manufacturers in an effort to identify and address noted deficiencies in their respective sampler performance. Each manufacturer has subsequently made progress in their instrument design and second generation instruments are becoming available.

In cooperation with OAQPS, ORD has also been developing draft specifications for Class III PM2.5 samplers. Class III instruments are designed to provide unattended, continuous operation and provide test results with time resolutions of 1 hour or less. Unlike the PM2.5 FRMs and Class I and Class 2 instruments, Class III instruments are not specified by design and can incorporate any measurement methodology which demonstrates adequate agreement with collocated FRM samplers. Based on sensitivity analysis produced by OAQPS' data quality objective model, draft testing requirements and acceptance criteria have been developed for Class III in

Relevance :Automated, continuous, or semi-continuous methods for determining PM mass concentrations that will work for a wide variety of aerosol types and weather conditions are needed for several reasons: to reduce network operation costs, to provide real-time data for issuing public health advisories, and to obtain data of higher time resolution for use in health studies and source-receptor modeling. Unfortunately, existing methods have often been found to have performance differing from PM mass reference methods. Sampler manufacturers continue to develop existing and new products in an effort to produce better samplers. Unbiased evaluation of these new or revised samplers is needed to determine if they meet the Agency's requirements. Ultimately, better PM samplers and data will enable EPA to better protect public health by reducing exposure to harmful levels of PM.

In conjunction with the U.S. Court's vacating the 1997 PM10 standards, the growing evidence of coarse particle heatlh effects has dictated the need to monitor the coarse fraction of PM10. While several designated methods exist for monitoring the fine fraction of PM10, few methods exist for the measurement of PMc with known data quality. The development of reference and equivalent PMc monitoring methods will give State, Local, and Tribal monitoring organizations the tools needed to determine compliance with PMc regulations, issue timely and accurate public health advisories, conduct PMc trend analysis, and develop effective state implimentation plans. Because accurate PMc measurement data is relatively limited compared to that of PM2.5 or PM10, routine monitoring of PMc will also provide health scientists the data necessary to accurately assess adverse health effects associated with exposure to PMc.

Clients :OAQPS (Rich Scheffe), Regions, States, Locals, Tribes

Project IDs:

ID Code :19541

Project type :OMIS