Research Priorities for Airborne Particulate Matter IV. Continuing Research Progress (2004) / Chapter Skim
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1 Introduction
1 Introduction
Pages 24-46
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It also directed the EPA Administrator to arrange for the NRC to provide independent guidance for planning the research program and monitoring its implementation. Specifically, the committee was charged with assessing research priorities, developing a conceptual research plan, and monitoring research progress made over 5 1PM10 refers to particulate matter collected by a sampling device with a sizeselective inlet that has a 50% collection efficiency for particles with an aerodynamic diameter of 10 :m.
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Immediate Priorities and a Long-Range Research Portfolio, proposed a conceptual framework for a national program of PM research (Figure 1-1) ; identified 10 high-priority research topics linked to key policy-related scientific uncertainties (Box 1-1)
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disposition of (including formation of sources and sinks of particulate matter secondary particles particulate matter presented to an from gaseous individual precursors) , and transport in air FIGURE 1-1 A general framework for integrating particulate matter research.
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Research Topic 3. Characterization of Emission Sources What are the size distribution, chemical composition, and mass emission rates of particulate matter emitted from the collection of primary-particle sources in the United States, and what are the emissions of reactive gases that lead to secondary formation through atmospheric chemical reactions?
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. The committee searched widely and comprehensively, but not exhaustively, to identify research in progress and research findings for this report, using various methods, such as workshops, literature reviews, research publications considered for EPA's PM "criteria document" (EPA 2002, 2003a)
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To reduce the uncertainties about airborne PM, research evidence is needed that fills in data gaps related to the scope of PM health effects and to the underlying processes by which PM exposure causes health effects. 3Time-series epidemiological studies evaluate associations between changes in health effects and changes in exposure indicators (for example, ambient PM concentrations)
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Improvements that need to be achieved include better measurement and characterization of both ambient PM and PM 4The Clean Air Act requires EPA to set NAAQS for certain pollutants known to be hazardous to human health and the public welfare (for example, damage to forests and degradation of atmospheric visibility)
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· PM10+: particles greater than 10 :m in aerodynamic diameter. Assessing the health effects of PM is complicated by the diversity and richness of particles typically present in ambient air.
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Analytical strategies range from a focus on major mass fractions, often broadly defined, to targeted studies of biologically relevant species or properties or to comprehensive efforts to resolve trace elements and compounds indicative of specific emissions. Trade-offs are of course inevitable amongthemany possibledimensionsofresolution -- intime,space,particle size, and physical state and in elemental and molecular composition (McMurry 2000)
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The complexity of the particle mixture nevertheless requires explicit acknowledgment if the needed integration of research is to be achieved. Research Approaches Many exposure assessment studies have now been carried out to measure personal exposures of people to particles and to understand the relationship between personal exposures and concentrations of particles recorded at centrally sited monitors.
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(c) Sodium-containing particle likely formed by reaction of sea salt with gas-phase nitrogen oxides and sulfuric acid.
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35 particle.a distribution of The 1969. diameter the to refers Dp August-September volume.
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Controlled human exposure studies offer the opportunity to study small numbers of human subjects under carefully controlled exposure conditions and gain valuable insights into both the relative deposition of inhaled particles and the resulting health effects. Individuals studied can range from healthy people to individuals with cardiac or respiratory diseases of varying degrees of severity.
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Rather, as in studies of diluted emissions from a specific source, such as a diesel engine, the intent is to attempt to derive some understanding about the influence of emissions from that source on health outcomes. In other cases, one or a few types of atmospheres, including specific forms of PM, such as black carbon or residual oil fly ash, have been studied.
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Together, the Health Effects Institute and EPA have maintained a database of research projects, but maintaining complete and up-to-date information has proved difficult. The approaches used in this report provide an indication of the substantial scope of the research now in progress.
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Studies 4.0 4.0 4.0 4.0 4.0 3. Emission sources 2.5 2.5 2.5 2.5 4.
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. dResearch management includes research planning, budgeting, oversight, review, and dissemination, cumulatively estimated by the committee at 10% of project costs.
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1.0 21.0 26.0 26.0 25.0 25.0 6.0 1.0 1.0 aTechnical-support expenditures by all public and private sponsoring organizations. bThe committee provided these cost estimates as initial guidance to the development of this research investment portfolio.
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Air-quality models Total $0.5 $0.4 $6.6 $7.2 $7.4 $9.2 Intramural $0.0 $0.4 $6.0 $6.7 $5.5 $7.0 Extramural $0.5 $0.0 $0.6 $0.6 $1.9 $2.2 5. Assessment of hazardous PM Total $7.9 $7.9 $8.1 $6.7 $16.1 $11.1 components Intramural $4.1 $3.3 $4.8 $4.5 $12.1 $8.0 Extramural $3.8 $4.6 $3.2 $2.2 $4.1 $3.0 6.
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8. Susceptible subpopulations Total $8.4 $2.7 $2.9 $2.7 $4.7 $4.8 Intramural $3.9 $2.4 $1.9 $1.7 $1.7 $2.2 Extramural $4.6 $0.3 $1.0 $1.0 $3.0 $2.6 9.
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Intramural includes EPA personnel salaries and expenses, contracts, and cooperative agreements. cManagement expenses includes salaries and expenses for EPA management personnel.
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To complete its task, the committee evaluated progress on a research agenda intended to resolve key scientific uncertainties, but the outcome of the evaluation largely reflects process rather than findings. In this regard, the committee's work is distinct from that of the Clean Air Scientific Advisory Committee of EPA's SAB, which critically evaluates the criteria document and staff paper.
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Chapter 4 provides an integration of progress made across the research topics, and Chapter 5 identifies key, overarching scientific challenges for the years ahead in completing the research portfolio on PM. Chapter 6 provides guidance on key management issues that the committee expects to be relevant for successfully addressing key priorities for PM research in the future, and Chapter 7 provides an overall synthesis and conclusions.
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