This Strategic Workplan for Particulate Matter Research is designed to provide direction for the research on particulate matter (PM) being undertaken by and on behalf of the transportation community. It identifies a set of five research focus areas and describes the priority research projects necessary to most effectively develop needed information and tools and to target resources.
PM is the term used to describe a complex mix of solid particles and liquid droplets found in the air. The United States Environmental Protection Agency (EPA) established major changes to the National Ambient Air Quality Standard (NAAQS) for PM in July 1997. The revised NAAQS are expected to have wide-ranging impacts on the transportation community, including:
An expected increase in the number of PM nonattainment areas, particularly in the eastern United States, thus greatly expanding the number of state departments of transportation (DOTs), metropolitan planning organizations (MPOs), and local transportation agencies that are affected by PM regulations;
A focus on combustion processes (including vehicle engines), as a major source of PM, particularly in urban areas where combustion-related emissions are likely to compose a greater share of total emissions, thus increasing the likelihood of more widespread transportation-related control programs for PM; and
An emerging recognition of PM as a regional problem, caused in part by secondary PM, that is formed and transported over great distances, thus redefining PM, in part, from a local to a regional-level issue and expanding the need for broader emission control programs.
There are, however, major weaknesses in the basic analytic tools and data that are needed to develop appropriate policy responses. In particular, policymakers charged with responding to the new standards are challenged by a limited understanding of spatial and chemical trends in ambient PM emissions, inaccurate and incomplete emissions inventories, and inadequate emissions models. The large gaps in information necessitate targeted research focused specifically on the needs of the transportation community that:
Identifies gaps in the PM science knowledge base that are hindering policy development;
Supplies an objective information foundation suitable for developing the next generation of transportation-related policy tools and techniques; and
Coordinates the PM research program for transportation sources with existing and future research initiatives.
The Workplan was developed with input from transportation and air quality experts throughout the country. It draws extensively on information gathered in a detailed literature review of PM research, and on the results of a one-day symposium with transportation and air quality experts held in January 2000.
The final output of this Workplan is a set of priority research projects. The projects are intended to fill PM research gaps that are most critical to the transportation community. Within the Workplan, the priority projects are categorized according to five broad research focus areas (monitoring, characterization, transportation sources, modeling, and control strategies) and how they address four key transportation policy questions. By linking research focus areas to resolution of key transportation policy questions, implementation of the Workplan will facilitate development of information, tools, and approaches that transportation agencies can use to handle emerging issues related to the new PM standards.
In the coming years, two critical policy issues for transportation agencies in PM2.5 and PM10 nonattainment areas will be developing appropriate transportation control strategies and demonstrating "conformity" of transportation plans. Their ability to carry out these activities, however, is constrained by gaps in knowledge and a lack of tools. Addressing these and other issues will require resolution of four policy questions:
These four questions provide a framework for undertaking the priority projects in the Workplan, first by determining where PM is a problem and where the problem is coming from, and then by developing effective transportation control strategies.
Focus Area One: Monitoring. The research goal of "focus area one" is to ensure that enhancements to the Nation's PM monitoring system improve understanding of the contribution of transportation to PM. The EPA's ambient air quality monitoring program provides the data needed to track air quality throughout the United States. The data gathered by the PM monitoring system provide a major source of information for the designation of future nonattainment areas, as well as for tracking compliance with NAAQS, and developing emissions modeling tools, emissions inventories, and control programs. EPA, in coordination with state air quality agencies, is presently expanding the PM monitoring system to support future NAAQS. These networks will substantially improve the capability of the PM monitoring system to address the new PM2.5 NAAQS. The monitoring systems, however, may not be adequate to provide data needed for accurate determination of transportation sector-related PM emissions. Project P1 will analyze preliminary data from the PM2.5 monitoring network to identify potential PM2.5 nonattainment areas. Project P2 will integrate critical transportation sector PM research concerns into EPA's supersite PM research program. Project P3 will examine state-of-the-art techniques for measuring the semi-volatile component of PM.
Focus Area Two: Characterization. The research goal of "focus area two" is to advance understanding of the spatial occurrence of PM and its sources, with an emphasis on PM2.5 and secondary PM formation. Characterization of PM draws on spatial and chemical analysis of monitoring data to improve understanding of where PM problems occur and how they are caused. Accurate characterization of PM can help to ensure that equitable and effective control strategies are developed. At present, however, understanding of the spatial and chemical characteristics of PM2.5 is based on a small number of region-specific studies. This research does not fully address key PM characterization concerns that are relevant to transportation agencies, such as the likely extent of areas that will be affected by PM2.5 regulations, the magnitude of secondary PM formation and transport, and the relative contribution of transportation sources to PM2.5. Targeted analysis of the data collected by improvements in the PM2.5 monitoring network will be vital to answering these questions. Project P4 will review and update transportation-related source profile information used in PM speciation analysis. Project P5 will utilize speciation monitoring data to provide an improved understanding of the relative contribution of transportation to PM.
Focus Area Three: Transportation Sources. The research goal of "focus area three" is to improve understanding of motor vehicle-related sources of PM and PM precursor emissions. Despite several decades of regulation on PM emissions, relatively little is known about the operating variability of PM emissions from motor vehicles as a result of changes in speed, engine deterioration, fuel and driving behavior. Recent studies for light-duty vehicles have begun to expand this knowledge. However, additional research is needed. Project P6 will conduct dynamometer studies of diesel-fueled vehicles/engines that are representative of the current fleet mix to generate better data on the contribution of diesel vehicles to PM and PM precursor emissions. Project P7 will conduct dynamometer studies of sample vehicles to determine the impact of gross emitter gasoline powered vehicles on PM emissions. Project P8 will examine re-entrained road dust contributions to PM2.5 in urban areas in the eastern United States.
Focus Area Four: Modeling. The research goal of "focus area four" is to improve PM emission modeling for transportation sources. The PART5 model is EPA's accepted motor vehicle PM emissions model, and is required in the development of PM10 inventories and analyses. The accuracy of emission factor models is important because these models are used to develop emission inventories and to evaluate the emission effects of transportation projects and control strategies. The quality and accuracy of user inputs to the models, such as vehicle travel data, are also important for accurate inventory development and analysis. It is widely recognized that the PART5 model contains a number of weaknesses that limit the precision of the model. The following priority research projects are designed to fill gaps in modeling techniques and improve the accuracy of emissions estimates. Project P9 will develop a coordinated model improvement program for incorporating new research on motor vehicle-related emissions into EPA's PM model on a timely basis or will develop new models as necessary. Project P10 will identify improvements needed in travel data to improve the use of the PM emission model for inventory development and analysis. Project P11 will develop an approach to the ammonia emissions component for possible inclusion in one of EPA's motor vehicle emission factor models.
Focus Area Five: Control Strategies. The research goal of "focus area five" is to improve understanding of the costs and effectiveness of PM control strategies for transportation sources. With the potential for a significant number of new PM2.5 non-attainment areas under the new NAAQS, there is an increased need to improve understanding of potential control measures for transportation. Project P12 will analyze the costs and effectiveness of existing transportation source PM control strategies at reducing PM and PM-precursor emissions. Project P13 will develop a menu of transportation-source PM2.5 control strategies for regions to consider in air quality planning, including an evaluation of costs and effectiveness in different geographic settings. Project P14 will evaluate the interactions between transportation-related PM and ozone control strategies, and other air pollutants.
The research focus areas and priority projects outlined in this Workplan provide a map for conducting future transportation-related PM research. However, additional steps will be required to implement the Workplan, including development of detailed project scopes, identification of project leadership roles, and selection of funding opportunities. Important implementation issues include:
Multiagency implementation approach. FHWA acknowledges that the technical complexity and broad scope of the projects contained in the Workplan will require a multiagency implementation approach. Extensive coordination between FHWA, state DOTs, and MPOs will be critical; however, the multidisciplinary range of projects outlined in the Workplan will also necessitate extensive involvement by academic and applied research organizations, as well as state and federal air quality agencies, and industry groups. An open dialogue among all these groups is encouraged to facilitate speedy resolution of issues critical to implementing this Workplan -- particularly, equitable distribution of research leadership, development of detailed project scope information, and funding responsibilities for individual projects.
Project implementation time frame. An aggressive four-year time frame is envisioned for conducting the research described in the Workplan. Adherence to this schedule will ensure that completion of the research generally coincides with EPA's planned designation of new nonattainment areas and improves the ability of state DOTs to develop timely and appropriate transportation policy responses.
Project scheduling. This Workplan does not include a specific time line for the initiation of individual projects. This plan, however, recognizes that certain projects must be initiated before others because they answer questions that need to be addressed early on by transportation agencies and because their findings and outcomes will help lay the foundation for other projects.
In terms of DOT's key policy concerns, research focus areas 3, 4, and 5 (transportation sources, modeling, and control strategies) are of most direct relevance. However, research focus areas 1 and 2 (monitoring and characterization) are acknowledged to provide critical background information on PM, without which sound policy decisions cannot be made.
Communication of research results to transportation stakeholders is an important aspect of the implementation of this research Workplan. The products of all the research projects need to be accessible to transportation professionals, and in some cases, special outreach methods and training will be required. Possible methods for distributing information about the research results might include development of a PM Web site, or newsletter, as well as conferences and seminars.