Working Draft, July 25, 1996

Joint Work Group Issue Paper on Designations for New NAAQS

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This is a preliminary document prepared by representatives of the Base Programs Analyses and Policies, National and Regional Strategies, and the Science and Technical Support Work Groups supporting the Federal Advisory Committee Act (FACA) Subcommittee. This is not an EPA document. It is subject to further workgroup discussion. Comments will be compiled and the work group representatives will revise the document as necessary.

Interested people should forward their comments to:

Steve Gerritson, LADCO representing BPAPWG @ 847-296-2181

Don Thieler, Wisconsin representing NRSWG @ 608-266-0603

Tom Moore, WESTAR representing STSWG @ 503-220-1660

ISSUE TITLE: DESIGNATION ISSUES FOR NEW NAAQS

Description

Under the 1990 Clear Air Act Amendments, areas in which violations of the standard for any of the criteria pollutants have been observed are designated as nonattainment areas. Currently, nonattainment area designations try to do two jobs at once: delineate areas where the NAAQS is violated, and delineate areas where controls are needed. The presumption has often been that controls are needed everywhere in the the designated nonattainment area and nowhere outside it. Traditionally, the boundaries have been political boundaries, such as county lines, that may not reflect either the area of violation or the area that contributes to the violation. In cases involving long-range transport of pollutants, these two types of areas will not coincide. Nonattainment designation triggers various regulatory requirements, and residents and industries within these areas must bear the responsibility of reducing emissions by an amount sufficient to bring the area into attainment within specified times. Although there are exceptions (notably the Ozone Transport Region and certain areas which can demonstrate that the exceedances are the result of overwhelming transport), the area where the violation occurs is presumed to be completely responsible for the violation. Thus, in spite of the exceptions cited above in the case of ozone, both ozone and PM-10 are viewed de facto as local problems with local solutions. This has led, in some areas, to a series of adjacent nonattainment areas, each presumed for purposes of control to be independent, but in fact recognized to be all part of one problem. Examples of this are found in both the area around Lake Michigan and the Northeast Corridor.

Much of the field research on and investigation of air quality problems over the past decade has been directed at understanding the relationships between the sources of pollutants (and their precursors) and recorded violations, that is, the phenomenon of transport. While this phenomenon is recognized as real, its extent and the magnitude of its impacts have not yet been fully identified, and major cooperative efforts, such as the Ozone Transport Assessment Group (OTAG), the North American Research Strategy for Tropospheric Ozone (NARSTO), and the Grand Canyon Visibility Transport Commission (GCVTC) are under way to increase our knowledge and understanding. It is fair to state, however, that, with respect to ozone and its precursors, there has been a shift in thinking from a view which looked at cause-and-effect relationships between single monitored violations and local emissions sources, to a view which looks at atmospheric loading over time and over a much broader region. Similarly, although more recent, there has been a shift in thinking concerning the nature of the public health problem of particulates, from TSP to PM-10 to PM-fine. This has been accompanied by evidence that PM-fine and its precursors can also be transported over great distances, and that relatively large amounts of PM-fine particules can be formed in the atmosphere as well as emitted.

In spite of this shift in thinking concerning the problems of ozone and particulates, the current regulatory framework remains firmly rooted in the old view. The focus is on individual exceedances, while the responsibility for "correcting" the problem is limited to a small area around the monitor. In addition, the designation does not distinguish between the occasional "episode" or infrequent violation and the more serious situation of regular and frequent violations and high background levels.

Problem:

Nonattainment designations consist of five related components:

*	the basis of the designation (i.e. how was the determination of nonattainment made)

*	the size of the nonattainment area

*	the severity of the designation (i.e. the classification)

*	the control requirements triggered by the designation

*	the time allowed to reach attainment.

There are several problems associated with each component. While each is important, this paper will focus only on the first two, i.e., the basis of the designation and the size of the nonattainment area. The remaining issues will be addressed in other papers.

Basis of the Designation

The basis of the designation (that is, where the NAAQS has been violated) for ozone and PM-10 has been monitored air quality data. For ozone, the size and shape of the nonattainment area has been automatically set by the size and shape of the political entity (SMSA or county) containing the location where NAAQS violations were measured. For PM-10, this same method has been used in some cases, but other methods were used in other cases, leading to various kinds of nonattainment area boundaries.

Two general approaches are in use to gain information about air quality: monitoring and modeling. There are problems associated with each. Monitoring is subject to two problems:

*	physical constraints and technical limitations ofindividual monitors

*	limitations of the monitoring network, both geographic and technical.

Monitoring equipment for both ozone and particulates is inherently constrained by several technical factors. For example, ozone monitors are relatively difficult to calibrate and to maintain in an "accurate" mode. Their performance can deteriorate "in the field," so that readings can be biased by up to 10%. PM-10 monitors rely upon filtering systems to capture suspended particulates, and are susceptible to contamination, and artifact that can increase or decrease reported value. Also, at this time, there is no Federal Reference Monitor for PM-fine.

Yet while accuracy of individual monitors may be substantially improved through a good quality assurance and quality control program, there are other limitations to monitoring. For example, an individual monitor can measure the amount of ozone or particulates in the air mass immediately surrounding its location, but cannot tell the actual extent of the area which does not meet the standard. A monitor does not clearly indicate whether the ozone is fresh or old, widespread or in a plume; what the sources of fine particulates are, although chemical analysis of the "catch" provides clues to these questions. Nor can monitors relate ozone to PM. Similarly, the measurement of regional haze does not relate the problem to fine particulates. In short, monitors only indicate where, and to what degree, air quality standards are being violated. They provide little information about the areas and sources contributing to the violations.

Of greater concern than the limits on individual monitors, perhaps, are the limits placed on monitoring networks. (The term "network" may be a misnomer, since there is no holistic use made of the system. It is merely a number of individual monitors, spatially distributed.) Resource constraints are the major limitation. Monitors, and the personnel required to operate and maintain them, are expensive. In some cases, inertia plays a role: the monitors have always been at their present locations, therefore they should remain there. Finally, there are disincentives for increasing the number or changing the distribution of monitors: by identifying additional problems, an area may be designated as nonattainment or "bumped up" to a higher classification. Thus the current system discourages the expansion of the monitoring networks, and hence the improvement of our understanding of the problem, unless it is done informally or as part of a one-time study.

Modeling is the other primary tool used to make air quality determinations. It is able to overcome some of the limitations which monitors are subject to. Most importantly it can provide information on the geographic extent of a violation or set of violations. It also is the primary tool in establishing the relationship between emissions and air quality observations. One of its primary functions is to predict the impact of changes in emissions on air quality. However, modeling of ozone, PM-fine, as well as regional haze is subject to a number of limitations including:

*	lack of fundamental scientific information and resources needed to formulate more accurate models

*	lack of data and in other cases the poor quality of the inputs (emissions,meteorology, initial conditions and boundary air quality

*	conservative bias in the face of inaccuracy.

Even the best models are not accurate enough to form the sole basis of a nonattainment designation. Sophisticated models have been developed over the past 20 years to predict ozone concentrations with accuracy of plus or minus 25%, but they require massive amounts of emission and meteorological data as inputs, and need to be evaluated against monitored data. For PM-fine, models are in the early stages of development. Traditionally, models have been considered acceptable for use if they predict long-term peak concentrations for an area (not a specific location) within a factor of +30% for ozone.

A model's outputs can be no better than its inputs. Pollutants like ozone and PM-fine (as well as the regional haze caused by PM-fine) are formed, wholly or in part, from chemically different precursors emitted over possibly large geographic areas. For such pollutants, a vast amount of information about emissions of several species and meteorology over a large region would be needed to predict concentrations accurately, even if the scientific principles programmed into the model were perfect. Gathering such information is subject to many of the difficulties discussed above under air quality monitoring. Emissions are often estimated using many approximations and are assumed to be relatively constant over time. Even when measured emission data are available, the measurements are subject to the same sort of inaccuracies as ambient air quality monitors. Most of the emission point sources that are measured are tested only occasionally (for example, annually) rather than continuously; it is unlikely that their emissions are constant. Meteorological inputs are based upon data gathered by a finite monitoring network.

In the face of these modeling issues, EPA and other regulatory agencies have insisted that models be protective of air quality; that is, when assumptions must be made that these assumptions be made in a manner which would increase the predicted concentration. Clearly, no community will accept a nonattainment designation based only upon a modeled, therefore theoretical, violation. To prove that a NAAQS has been violated, monitoring data are needed. On the other hand, to establish the areal extent of violations, modeling is a necessary tool. Monitoring can be used to confirm the modeling. The current designation system also has other problems:

*	the failure to take into account the phenomenon of transport

*	baggage carried by the term "nonattainment" itself.

The failure to account for transport remains a major deficiency of the current system. For the most part, a nonattainment area is considered responsible for all observed exceedances, without regard for upwind sources. As discussed above, there has been a shift in thinking on both ozone and PM, which looks at the complex interplay of atmospheric, chemical, and topographic influences. This thinking is not reflected in the initial designation or the mitigation.

In the present system, the size or geographic extent of the nonattainment area is important, since it is assumed that there is a cause-and-effect relationship between emissions and activities in the area and observed violations of the NAAQS. While there are mechanisms in the 1990 CAAA which provide for situations such as transport, they are either difficult to use or carry with them severe requirements, both of which are disincentives. Generally, it has been the MSA or the County which has had to bear the responsibility for air quality violations. This may often treat the symptoms rather than the disease, and may place unfair burdens on one area. In addition, the problems of one nonattainment area may be compounded by an adjacent nonattainment area, on a different schedule and with different priorities for mitigation.

Finally, a note on terminology. The term "nonattainment" carries with it a negative connotation and a set of stringent requirements. As a more accurate description, and more neutral terms, we suggest consideration of the options: "areas of violation" to describe those areas in which violations of the standard are observed; and "areas of influence" to describe those areas which contribute to the violations.

Issue #1 - Should the approach to designation be changed to include areas which contribute to violations as well as areas which experience them?

Options

Option 1 - Continue current practice. As described above, the current practice is essentially to designate as nonattainment the county or Standard Metropolitan Statistical Area (SMSA) in which monitored violations of the NAAQS have occurred. This option requires that contributing sources outside the designated nonattainment areas be addressed and controlled outside of the designation process, either through mechanisms within the Clean Air Act or through regional agreements.

This option has the advantage that it is a familiar approach and would not require any major changes in guidance and would work quite well for the limited situations where the area experiencing the violations is essentially the same as the area which is contributing to the violations, and happens to coincide with a county or SMSA.

This option has a number of significant disadvantages which have been discussed in detail in the background portion of this issue paper.

Option 2 - Expand the designation of the nonattainment area to include all of the areas contributing to the violation as well as the area experiencing the violation. This would require a major expansion of many of the current nonattainment designation areas beyond the local county or SMSA boundaries.

This option has the advantage of providing a means to address and deal with the problem of transport, and of treating regional problems in a unified and more efficient manner.

However, it has several drawbacks. First, the current structure of the Clean Air Act would require uniform application of nonattainment requirements to a much broader area regardless of circumstances. For example, Inspection/Maintenance Programs might be required in relatively rural areas, or VOC reductions might be required in areas where NOx reductions would be most cost effective. Also LAER and Offset and other nonattainment requirements would be automatically extended to these areas. It also would not recognize that there are areas experiencing violations which are due to overwhelming transport and which do not significantly influence their own air quality. The nonattainment designation also implies that the area is not meeting the standards when in fact many of these contributing areas do meet the air quality standards themselves. This does create a lot of confusion and would undoubtedly lead to resistance to the nonattainment designation because of the term "nonattainment".

Finally, this option requires a level of technical analysis and precision which may be beyond the capabilities of existing modeling and analytical tools.

Option 3 - Separate the nonattainment designation into two parts - The first part being a designation of an "Area of Violation" (AOV). The second being a designation of an "Area Of Influence" (AOI). These designations would be quite separate but would occur in tandem. The AOV would identify the entire area which is not meeting the ambient air quality standard. The major requirement associated with designation, as an AOV would be for public health warnings when appropriate. The AOV designation would require an identification of an AOI. The AOI should, based on sound technical information and science, identify the area that contains sources or groups of sources that contribute to the exceedance of the ambient standards in the associated AOV. The areas identified as AOI's would be required to develop a spatially integrated control strategy, which would take into account national controls on certain sources, regional efforts to reduce transport, and state and local controls where appropriate. For regional haze, the Class I areas would correspond to AOVs, while AOIs would correspond to planning areas.

This option has the advantage of overcoming some of the disadvantages identified in option 2 as well as the other problems outlined in the description portion of this paper. It is a new approach which moves away from the existing problems.

As with option 2 this option has the disadvantage of requiring a difficult technical analysis to be done for which current techniques available may be stretched beyond their current capabilities. It also will be difficult politically to identify these areas because of the potential for extending control requirements to the AOI.

Option 4 - In the designation process identify only the Area of Violation (AOV) and not the AOI with broad subnational regions being identified as potentially contributing regions. This option would be similar to option 3 for the identification of the AOV but adds the identification of broad subnational regions or in the extreme the nation as a whole as potential contributing regions. By Subnational regions the expectation would be that it would include large collections of states such as the Midwest, the Southeast, New England, etc. Such an area would be identified if there was a reasonable expectation that the subnational region contained significant collections of sources contributing to the AOV. The expectation is that the subnational areas then would be required to apply uniform control requirements across the entire subregion to deal with the air quality problems.

This option would result in a relatively simple approach that would avoid some of the technical difficulties associated with options 2 and 3. It would also create a level playing field within the subregions because all similar sources would be subject to the same control requirements.

The obvious disadvantage of this approach is that uniform controls would be politically difficult to implement in areas where there is not a clear technical demonstration that the controls will result in air quality improvement in the AOV's.

Recommendation: Option 3 is recommended. Many believe that new approaches are needed for the designation process or for the process of appropriately identifying the areas responsible for impacting certain monitors that are not meeting the NAAQS. It is the conclusion of the work group that the current concept of nonattainment areas is not adequate to properly address broader transport issues which are relevant to ozone, fine particles, and regional haze. Such an approach combines the ability to address broader transport issues with the ability to continue to implement local controls as necessary. Those problems that are truly local should continue to be treated as such in an expeditious manner.

Class I Areas - For Class I Areas where regional haze has been identified as an air quality related value this recommendation assumes the following considerations;

1.	The Class I Area itself would be the equivalent of the area of violation.

2.	The Area of Influence would include all of the area which is adversely influencing visibility in the Class I Area of interest.

Issue #2: How should Areas of Violation (AOVs) be defined and identified?

Options

Option 1. AOV boundaries should be defined solely by the geography of the ambient monitors where violations have been measured, these boundaries should be refined by analytical methods (including modeling, review of source data, review of emissions inventories, and statistical tools).

The advantages of this approach are that air quality problems, as defined by violations, are identified for the protection of the public, while the boundaries of the AOVs are set by a combination of monitoring and analytical tools which help to make the determination as to whether the individual violations are linked through transport, common sources, etc.

The disadvantages are that many areas have insufficient (or no) monitors, that no Federal Reference Method for PM-fine currently exists, and that AOVs which cross state or local jurisdictional lines may be difficult to accept politically.

Option 2. The regions of monitored (or modeled) violations should be within the same political boundary area, which would then define the AOV.

The advantage of this approach is convenience, particularly if controls are warranted to reduce the levels of precursor pollutants. The disadvantages are that the unity of the problem is ignored and the erroneous perception of discreteness is perpetuated. In some cases, as in the West where counties are larger, this approach can include areas where there are no violations.

Option 3. The monitors that measure violations of ozone and PM-fine must be impacted by the same local sources. The area encompassing these local sources and the violations would then be used to define the AOV.

Advantages of this approach are that it links the violations to the local sources, and that it attempts to link ozone and PM-fine violations. Disadvantages are that it may be difficult to differentiate between local and non-local sources, and that ozone and PM-fine violations can occur independently, in some cases at different times of the year.

Recommendation: Option 1 is recommended. The boundaries of AOVs should define those regions which exceed ambient air quality standards, and thus readily define where the population is being exposed to unhealthy air. Such boundaries should be based on monitored data or, where available, on a combination of both monitored and modeled data. Modeling alone should not be the basis for determining AOVs, except that for the purpose of incentivizing monitoring, modeling could be used as a basis for AOV determination. (See issue paper on monitoring incentives for this approach.) It is also recommended that areas which are lacking monitors or in which the monitoring effort is insufficient,a monitoring plan should be required and implemented.

Location of sources should not be a basis for establishing AOV boundaries, and although political or similar (e.g. MSA) boundaries may be convenient, they should not be the overriding determinant for boundaries. Where AOVs of ozone and PM-fine overlap, co-AOVs may be defined, although it will be the local entity which determines whether a co-AOV boundary determination is appropriate. In such cases, there may be important advantages to having common planning timelines and SIP submittal dates, such that an integrated process can be accommodated. Flexibility should be given such that the option of common planning processes is available to the states.

It should also be noted that the designation of both areas of violation and areas of influence will be based on the standard promulgated by USEPA. In other words, if the standard requires an average of the values for the previous three years, then designations will be based on the same three years.

Class I Areas - For Class I Areas where regional haze has been identified as an air quality related value, the Class I Area boundaries would define the area of concern. It would constitute the Class I Regional Haze equivalent of the Area of Violation for ozone and PM-fine.

Issue #3. How should Areas of Influence (AOIs) be defined and identified?

This issue discusses options for determining the boundaries of the AOI and the general implications for being designated as part of an AOI. The AOI is a specified domain in which in includes, at a minimum, anthropogenic sources or groups of sources contribute to downwind AOVs. Thus, it is the determination of sources or groups of sources that defines the boundaries of the AOI. The options discussed below all assume that being included in an AOI will result in all portions of the area being required to be a part of a spatially integrated plan. It does not mean that all portions of the area will be required to implement regulations or have sources in all portions of the area be subject to regulations. This assumption is extremely important to understand and accept because it allows for a more inclusive approach to identifying th AOI. It should allow us to define large enough AOIs to encompass all of the potentially significant sources and groups of sources. If this assumption is not accepted then the process of designating the AOI will inevitably become much more technically and politically difficult and time consuming. With this in mind the operating principle in defining the AOI becomes that of including all areas or sources which might conceivably contribute to the violation. Dealing with identifying which portions of the AOI should be subject to regulation and just exactly what those regulations would be is the function of the spatially integrated plan. Dealing with these issues in the plan allows for a much fuller ability to deal with the real world complexity of case by case situations and should be avoided to the extent possible in the initial designations of the AOI. In addition, the AOI is defined as those areas which influence violations which have occurred, and is limited to existing sources. The issue of how new sources should be treated is left to subsequent discussion.

A spatially integrated plan means that a plan will be prepared that would in many cases be made up of a number of separate state implementation plans including the possiblity of different control strategies in each plan, and could also include separate federal regulations which would cover all or a part of the AOI. These separate plans and federal regulations must be It does not mean that all portions of the area will be required to implement regulations or have sources in all portions of the area be subject to regulations, integrated in such a way that when taken as a whole they will result in a plan which brings the associated AOV into attainment of the standard within the required time frame.

The following subissues are put forward for consideration when an adequate air quality model is developed for identifying the AOI.

SUBISSUE - A - Should AOI's be identified based on all emissions including concentrations of nonanthropogenic emissions or should the designation be limited to a consideration of only anthropogenic emissions?

Alternative 1 -	This alternative would include all emissions, non-anathropogenic as well as anthropogenic, in the consideration of the identification of the AOI. It would ensure that all of the significant contributions to the AOV are included in the modeling domain.

Alternative 2 -	This alternative would include all antropogenic emissions in the identification of the AOI. This would include major and minor point sources, area sources,and mobile sources.It would not include consideration of the nonanthropogenic sources.

Discussion - The primary purpose of the AOI is to identify the area for planning a program for the control of emissions in order to meet the ambient standard. Since the nonanthropogenic sources are essentially assumed to be uncontrollable including them in the AOI determination could tend to confuse the issue and might result in the inclusion of large rural areas which have no significant anthropogenic emissions. On the other hand, it is important to include biogenic emissions in any modeling effort and to establish a realistic set of background conditions from which to develop a control strategy. It is important for states and localities inside or outside the AOI to cooperate in the development of inventories and modeling tools to aid in the development of control strategies.

Recommendation: Alternative 1 is recommended to ensure that all sources or groups of sources, regardless of origin, are included in the planning domain. This recommendation is contingent upon the assumption that the AOI is for planning purposes only. It does not infer that controls will be required in all portions of the planning area. This will be resolved in the planning process.

SUBISSUE - B - What geographic subdivision should be used to identify the AOI?

Alternative A -	Identify the AOI by state. This would involve modeling the emissions from an entire state and making a determination if the emissions influenced the AOV. If modeling showed that the emissions did contribute to the violations then the entire state would be included in the AOI.

Alternative B -	Identify the AOI by County and Metropolitan Statistical Area (MSA). The county would be used where no MSA was identified otherwise emissions from the entire MSA would be combined to determine if emissions from that geographic area influenced the AOV. An exception to this might apply to certain very large counties, particularly in the west where common sense would dictate tjat gepgraphic anomalies such as mountain ranges or deserts should be excluded from the AOI. In such an exceptional case then only a part of the county would be a part of the AOI. If modeling showed that emissions from that county or MSA did contribute to the violations then that area and all of the area between that area and the AOV would be included in the AOI.

Alternative C -	Identify the AOI by minor political subdivision (Town, census tract, zip Code, city, village etc). This would be done in the same fashion as A and B above.

Alternative D -	Identify the AOI using modeling grids. This would be done in the same fashion as A and B above but would totally ignore the political boundaries of the areas affected. The boundary of the AOI could be drawn along nearby political boundary.

Recommendation: It is recommended that Alternative B be used to identify the AOI. The county and MSA are the basic geographic building blocks upon which the emission inventory is built. It also is relatively homogenous in character and therefore characterizes a particular area. They are large enough to represent significan concentrations of emissions. They are relatively easy to identify and are common across the country. It is also recognized that in the west the counties tend to be much larger and may contain some very diverse areas within the boundaries of one county. In such situations it may be advisable to provide some flexibility in defining the AOI.

Using an entire state would result in larger planning areas and may include very larage areas where there is little indication of influence when looked at in more detail.

Using minor political subdivisions would result in a great deal more work because of the need to break the emission inventory down more finely for the modeling necessary. More importantly, it is not recommended because of the difficulty of modeling such a fine mesh of areas and truly identifying homgenous areas that influence the AOV's.

Use of the modeling grids was rejected because of the totally arbitrary nature of the areas being identified and the difficulty of designing a control strategy based on such boundaries. The modeling grid approach could also result in cities being split with one portion being included in the AOI and the other portion being outside. This would be a nonsensical result.

It should be recognized that AOI's could encompss a number of counties and SMSA's, and could cross state lines. In thes instances, preparation of a spatially integrated control strategy will require an institutional mechanism (such as OTC, OTAG, or the GCVTC) to facilitate and oversee the process and the implementation. This issue will be addressed in a subsequent paper.

Class I Areas - For Class I Areas where regional haze has been identified as an air quality related value the Area of Influence would be defined to include all of the area which is determined to adversely impact visibility in the Class I area of interest. It is important to note here that it does not include areas which might potentially adversely impact the Class I area, if emissions were substantially increased in that area. As noted earlier in this paper, the area of influence does not encompass areas which currently do not influence the Class I area or the AOV. It includes only the impacts of existing emissions. The issue of new source impacts must be addressed in the new source review paper which will follow this effort. For Class I areas the AOI can be used for plans to improve visibility but cannot be used alone to ensure continued maintenance of the existing or future visibility conditions.

SUBISSUE - C - Should zones of influence be made an integral part of the AOI designation process? For example an AOI might be identified which identified counties or MSA's with certain levels or types of emissions in one zone and those with larger levels or different types of emissions in a different or second zone.

Alternative A -	Develop AOI'S with zones of influence as a part of the designation process.

Alternative B -	Develop AOI's without zones of influence as a part of the designation.

Recommendation: The recommendation is to develop the AOI's without zones of influence. The advantage of zones of influence is that it can clarify the AOI and provide some screening to remove areas and types of sources which clearly are not influencing the AOV. This advantage would not be lost if it were made an early part of the planning process and could also simplify the remaining planning effort by removing areas and source types which did not affect the AOV. Adopting the recommendation means that the designation of the AOI can occur in an expeditious manner and the zones of influence can be timed and tailored to meet the unique circumstances of the affected AOI.

Note:	Maps which illustrate how AOI's might be identified using the recommendations provided here are available from the authors. These maps are crude drafts and are provided only for illustration and discussion purposes and are not to be construed to illustrate any actual conditions.

The following reflect options for identifying an AOI if appropriate models are not available for such purposes:

a)	The AOI would be defined using existing institutional structures, such as those from the Ozone Transport Assessment Group (OTAG, the Ozone Transport Commission (OTC), the Lake Michigan Air Directors Consortium (LADCO), the Grand Canyon Visibility Transport Commission (GCVTC), and California-based studies;

b)	A national approach or national AOI could be selected;

c)	For completeness, a final option, although one less desirable, is to ignore transport and focus all control measures within a specified distance from an AOV, for example, up to 300 km from the boundary of the AOV.

At this time, no recommendation has been made for this issue.

Joint Work Group Issue Paper on Designation Issues

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