Protecting Visibility in National Parks and Wilderness Areas (1993) / Chapter Skim
Currently Skimming:
7 Conclusions and Recommendations
7 Conclusions and Recommendations
Pages 239-264
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From page 239... ...
However, present scientific knowledge about visibility impairment in Class ~ areas has several implications for policy makers. GENERAL CONCLUSIONS Any effective strategy to accomplish the statutory goal of remet dying and preventing anthropogenic visibility impairment in Class ~ areas must limit emissions of pollutants that can cause regional haze.
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From page 240... ...
Because most visibility impairment in Class ~ areas results from the transport by winds of emissions and secondary airborne particles over great distances, focusing only on sources immediately adjacent to Class areas-as under the current program is unlikely to improve visibility effectively. A program that focuses solely on determining the contribution of individual emission sources to visibility impairment is doomed to failure.
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From page 241... ...
Reductions of these emissions are expected to occur in the next two decades as a result of He 1990 Clean Air Act amendments' acid rain control program. In the West, no single source category dominates; therefore, an effective contro!
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From page 242... ...
As shown in Chapter 6, the application of all commercially available control technology would reduce, but not eliminate, visibility impairment in mandatory Class ~ areas. Policy makers might develop a comprehensive national visibility improvement strategy as the basis for further regulatory action.
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From page 243... ...
The task force (now defunct) consisted of representatives from EPA, DOl, the Departments of Agriculture and Defense and was formed to develop long-term strategies for remedying regional haze and to recommend a long-range program to restore visibility in the national parks.
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From page 245... ...
Regulatory action in the environmental field typically is taken without complete scientific knowledge; this is inherent in a statutory scheme like the Clean Air Act that is based on a philosophy of prevention. A decision as to whether or how to take regulatory action is therefore not wholly one of science but also involves policy considerations, such as the relative risks of overprotection and underprotection, which were outside the committee's purview.
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From page 246... ...
This data base, however, has not been updated since 1984. In addition, the new permitting program established by Title V of the Clean Air Act creates a promising data base for tracking emission changes near national parks, especially those resulting from Title IV's acid rain control program.
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From page 247... ...
Over the past decade, progress also has been made in relating human judgments of visibility and various perceptual cues, such as contrast and visual range, to visibility changes measured by light extinction. An independent science advisory pane!
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From page 249... ...
The monitoring program should be designed to characterize the existing patterns of haze, trends in those patterns, and the pollutants that contribute to visibility degradation on a regional scale. National visibility monitoring networks, notably the Interagency Monitoring of Protected Visual Environments IMPROVES network, have been established to assess visibility impairment in the nation's Class ~ areas, to identify sources of haze, and to track trends in impairment conditions.
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From page 250... ...
To document adequately the visibility benefits from Title IV, monitoring networks in Me eastern states need to be expanded and long-range funding ensured. Otherwise, EPA will lack information needed to measure whether reasonable progress is being made toward the national visibility goal and will be unable to meet its responsibility under Section 169A(a)
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From page 251... ...
It is especially important that such trends be documented during the coming decade, so that the effect of acid rain controls on visibility can be determined. Airports should be equipped with integrating nephelometers that are sensitive enough to measure the range of haze levels encountered in the atmosphere.
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From page 252... ...
An accurate method for measuring particulate organic and elemental carbon, particularly at the low concentrations found in and near national parks, needs to be developed. Although organic and elemental carbon often are major constituents of atmospheric particles, atmospheric measurements of particulate carbon using different sampling and analytical methods can disagree by as much as a factor of 5.
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From page 253... ...
Commercially available instruments are needed for continuous measurements of particulate sulfates, organic and elemental carbon, nitrates, and elemental composition. Such instruments would be valuable for visibility research and monitoring as well as for work on other atmospheric problems involving airborne particles.
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From page 254... ...
Efforts should be made to develop instrumentation for continuous measurements of particle absorption coefficients. This instrumentation should be sensitive to the range of absorption coefficients obtained from atmospheric observations.
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From page 255... ...
. size distributions.: ::: .
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From page 256... ...
Speciated rollback models require data on aggregate emissions of SOx, NOx, VOCs, NH3, and primary airborne particles; chemical mass balance (CMB) receptor models require additional information on endemic tracers such as key trace metals found in source exhaust; and mechanistic models require further data on the particle size distributions in the primary source exhaust.
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From page 257... ...
From a visibility standpoint, the national inventories needing the most improvement are those for primary elemental and organic carbon particles and for VOCs that lead to secondary organic particle formation. Inventories for elemental carbon and primary organic particles essentially are nonexistent except for Los Angeles.
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From page 258... ...
to the comprehensive data base from the Denver Brown Cloud study. Receptor Models This section focuses on research needs specific to haze in national parks and wilderness areas.
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From page 259... ...
Moreover, some of the most reliable tracers, such as lead for motor vehicles, are disappearing from emissions as the result of control measures. A major data gap exists in present knowledge of source emissions profiles that would be useful in distinguishing types of sources, including domestic wood burning, agricultural and prescribed burns and wildfires, gasoline- and diesel-fueled motor vehicles, and coal combustion.
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From page 260... ...
Recent advances in mechanistic models (see Chapter 5) might greatly improve simulations of atmospheric physical and chemical processes that affect secondary particle formation, particle size distributions, dispersion, and deposition over long distances.
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From page 262... ...
The emissions reduction capabilities and the costs of commercially available control technologies for stationary and mobile point sources are well ciocumented. However, it is difficult to translate unit costs for a specific technology into aggregate costs for overall emissions reductions for an urban area or region.
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From page 263... ...
What is needed, overall, is the recognition that any effective visibility protection program must be aimed at preventing ant} reducing regional haze. An effective program must, therefore, control a broad array of sources over a large geographic area.
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From page 264... ...
264 PROTECTING VISIBILITY IN NATIONAL PARKS Although visibility impairment is as well understood as any other airpollution effect, gaps in knowledge remain. Filling these gaps will require an increased national commitment to visibility protection research.
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