This is a preliminary document prepared by a subgroup of members of the Base Programs Analyses and Policies (BPAP) Work Group as part of the Federal Advisory Committee Act (FACA) Subcommittee process. It is not an EPA document. Interested people should forward their comments to a member of the Base Programs Analyses and Policies Work Group.

Areas of Violation Boundaries

Date:	August 4, 1997

Contact:	John Crouch, Hearth Products Association, Telephone 916/974-1188,

Fax 916/974-8380, e-mail: crouchpa@ix.netcom.com

Status:	Draft #5. Incorporates comments from June 9, 1997 BPAP work group meeting.

Introduction

Section 107 of the Clean Air Act (CAA) requires the EPA to designate as nonattainment "any area that does not meet (or that contributes to ambient air quality in a nearby area that does not meet) the national primary or secondary ambient air quality standard for the pollutant." Designated nonattainment areas are subject to general nonattainment provisions, which include making reasonable further progress (RFP), developing an emission inventory, providing for contingency measures if RFP is not achieved, and other requirements. Additionally, major new or modified sources in nonattainment areas must comply with the lowest achievable emission rate (LAER) and must offset any emission increases by obtaining emission reductions from sources located in the nonattainment area.

Nonattainment areas have traditionally attempted to identify both the area in which a violation is occurring and the area which is causing or influencing the violation. However, sources that contribute to a violation are not necessarily located where the violation occurs. The traditional nonattainment approach works in cases where air pollution is locally generated (e.g., some urban centers), but it does not adequately address violations in rural or remote areas with few or no significant sources (e.g., White Top Mountain, VA).

In order to address broader transport issues which are relevant to ozone, fine particles (PM-fine), and regional haze, the Designation Issues for New NAAQS (7/25/96) issue paper recommends that the nonattainment designation process be separated into two parts -- identifying the "Area of Violation" (AOV) and determining the "Area of Influence" (AOI). This proposed designation approach would combine the ability to address broader transport issues with the ability to continue to implement local controls as necessary.

The Regional Air Management Partnerships and Areas of Influence (2/13/97) paper provides current definitions of elements of the proposed planning process. The AOV is the area determined to be violating a NAAQS. An AOI is a geographical area containing anthropogenic and natural sources which contribute to an AOV. The control region is an area within an AOI for which emission reductions of PM, its precursors, and/or precursors of ozone are deemed necessary to meet the NAAQS/regional haze objectives.

Class I areas with visibility impairment will be treated as Areas of Concern (AOCs) for the purposes of defining AOIs and developing plans for the regional haze program. Unlike ozone and PM AOVs where NAAQS violations occur, in regional haze AOCs (i.e., Class I areas) the goals would be to improve visibility conditions on the worst days and to prevent deterioration on the best days.1

Assumptions

This paper does not presume any geographic relationship between the sources influencing the violation (i.e., the AOI) and the violation itself. The following scenarios are possible:

The AOI and AOV boundaries could coincide.

The AOI and AOV could overlap.

The AOV could be completely contained within an AOI.

The AOI could be separated from the AOV by a distance.

This paper does not make any assumptions about which emission sources should be controlled (i.e., the control region). Given the above scenarios, the control region may or may not be part of the AOV. This paper only assumes that a state or set of states will work together to identify which emission sources need to be controlled to address the violation. The Institutional Mechanism for Development and Implementation of Regional Strategies (2/13/97) issue paper discusses the institutional mechanism in more depth.

Further, this paper does not presume whether or not the AOV is synonymous with a nonattainment area. Legal issues regarding the regulatory requirements triggered by a nonattainment designation, such as RFP, sanctions, and control strategies, will be addressed in other issue papers.

Finally, this paper does not presume that rural areas are free of emission sources. For example, national parks may have emission sources including, but not limited to, mobile sources (off road vehicles, airplanes, etc.).

Issues and Options

Issue #1:	What is the purpose behind defining AOV boundaries?

Several purposes for establishing AOV boundaries have been discussed. The Designation Issues for New NAAQS (7/25/96) paper, recommends the boundaries of AOVs should define those regions which violate ambient air quality standards, and thus readily define where the population is being exposed to unhealthy air. As such the AOV boundaries could be used to educate the public of the estimated spatial extent of a NAAQS violation registered at a monitor. It is hard to say with certainty who is exposed to concentrations above the NAAQS. However, boundary information should be made available so people living within or near an AOV can be knowledgeable that a NAAQS has been violated. In this manner the public is informed of a potential health hazard. If it can be determined that the spatial extent of a violation is changing then this information could be used to judge progress towards attainment. Also, AOV boundaries could be used to define the area in which regulatory requirements are applied. This would provide for emission reductions in the area surrounding a monitored violation, but it would not adequately address problems caused by transported air pollution and may create a disincentive for additional monitoring. Finally, the AOV boundary could initiate the regulatory/planning process. Once the AOV or AOC is determined, sources contributing to the violation or to regional haze would be identified (perhaps through the RAMPs' AOI analysis) and controlled (perhaps through SIP action by the state). To expedite the planning process, anticipated or expected AOVs could be identified.2 This may be implemented through the use of the "areas at risk" concept.

There are several purposes for AOVs that are not necessarily tied to boundaries. The AOV could count and track where violations occur. This would generate air quality information and could indicate trends over time. In addition, analyses of AOV boundaries could be used to revise the monitoring network. For instance, additional monitors could be deployed in areas where modeling indicates an air quality problem.

Issue #2:	How should PM and ozone AOV boundaries be determined?

Two different types of NAAQS have been proposed. One is based on a spatial average, and the other is based on a single monitor.3 Should the AOV boundaries be set to what is contained in the standards (spatial average or single monitor), or should an extra step be taken to estimate the spatial extent of the area violating the standard? Four options have been discussed.

1) Provide no boundaries. This would be quick and easy to implement but would not provide information in regard to the spatial extent of the violation.

2) Use political boundaries. Examples include counties, Metropolitan Statistical Areas (MSA), census blocks or groups of census blocks, and zip codes. This would also be quick and easy to implement. The use of political boundaries would assist in the proper characterization of the spatial representativeness of air monitoring sites and facilitate better presentations of air monitoring data on national, regional, and local maps. This would make it easy for the public to understand the location of the boundaries. Though this is not necessarily accurate, it may be appropriate given the uncertainty in the analyses available to estimate the boundaries. Problems associated with large counties in the West would need to be accommodated.

3) Conduct analyses to estimate the extent of the pollutant air mass the monitor represents. This method would more accurately characterizes the problem. The Designation Issues for New NAAQS (7/25/96) paper suggests boundaries of AOVs should be based on monitored data or, where available, on a combination of both monitored and modeled data and refined by analytical methods, including modeling, reviewing source and emissions data, and using statistical tools. Designations Issues also indicates that co-AOVs could be delineated where overlapping PMfine and ozone AOVs occur.

However, tools and data may not be available. Boundaries may change depending on episode chosen for analysis. The Scientific Issues Related to Defining the AOVs and AOIs (2/7/97) paper indicates that "there are three basic tools to help establish the domains of AOVs and AOIs: monitoring and data analysis, trajectory modeling, and air quality modeling. The only valid tool to determine the domain of an AOV is concentration monitoring. Air quality modeling, while essential for control planning, is not recommended because of the general lack of accuracy and precision in the input information. However, air quality modeling can help in locating ambient monitors needed to better define the boundary of an AOV (and an AOI)." Also, if political boundaries are not used the public would not readily understand where the boundaries are and presenting this information on a map would be problematic.

4) Use a zonal approach. Black, gray, and white zones would indicate the improving air quality at increasing distances from a monitor. This would provide more information and improve characterization of the problem. However, again the tools and data may not be available. Boundaries may change depending on episode chosen for analysis. Informing the public would be problematic. This zonal analyses may be helpful when determining AOI and control regions but it is unclear how this would help air quality managers in general.

Issue #3:	How should regional haze AOC boundaries be determined?

Three options have been discussed. 1) Split the country into Eastern and Western Regions for regional haze violations. 2) Use Class I area boundaries. 3) Use Class I area boundaries, and group the Class I areas.

Issue #4:	Should AOV boundaries be defined for individual pollutants, or should the boundaries encompass ozone and PMfine violations and visibility impairment?

In order to address this issue, the purpose for merging AOVs should be determined. Regardless of whether the AOVs are integrated, it is important to integrate the analyses so that control measures adopted for one pollutant do not exacerbate other problems and to identify areas with multiple-pollutant health risks. Options discussed include: establish separate PMfine and ozone boundaries; merge areas with overlapping PMfine and ozone boundaries to include both the ozone area and the PMfine area; or establish a third area which is the intersection of the ozone and PMfine violation boundaries.

Issue #5:	Who makes the initial AOV determinations?

The issue of who makes the initial AOV determinations is a policy decision which should be addressed along with other issues involving the procedures for initiating and reviewing designations. Options which have been discussed include: 1) EPA would initially determine AOVs, and states would be given the opportunity to comment, 2) states would initially determine AOVs with EPA comment and approval, and 3) Federal Land Managers (FLMs) would have a role in determining regional haze AOCs. Along with the initial determination of AOV boundaries is the issue of reviewing AOV boundaries. This should address when AOV boundaries are modified or expanded after initial determination.

Issue #6:	How should the timing of AOV determinations be addressed, in the event that ozone and PMfine designations are not simultaneous? Should ozone AOVs be determined first and then PMfine AOVs?4

Recommendations

AOVs initiate the planning process. This process should begin as soon as possible. Therefore, AOV boundaries should be determined quickly, and a lot of resources and time should not be spent drawing highly specific (scientifically defined through a thorough analysis of the available data) boundaries. Political boundaries and a minimal amount of analysis are sufficient for AOV boundaries. If the state or tribe having jurisdiction later determines a scientific basis and a compelling need to adjust the boundaries of the AOV, this could be accomplished administratively. That is, the initial determination need not wait for all of the available science to be completed.

EPA should provide guidance on the criteria for determining AOV boundaries. AOV boundaries should be a minimal size necessary to identify spatial extent of area with potential health hazards. Controls within an AOV would address local emissions but would not address the sometimes larger issue of transported pollutants and precursors. It is not recommended that AOV boundaries equate to control regions. It is strongly recommended that RAMPs quickly identify preliminary AOI boundaries and control regions and that these areas (AOI and control regions) be used for the purpose of adopting control measures and implementing regulatory programs (such as LAER, NSR, and RFP).

Establishing regional haze AOCs would not require drawing boundaries, since Class I areas already have boundaries and additional boundaries would not be set around them.