DRAFT

This document was prepared by a subgroup of members of the Base Programs Analyses and Policies Work Group as part of the Federal Advisory Committee Act (FACA) Subcommittee process. It is not an EPA document. It is subject to work group discussion. Interested people should forward their comments to a member of the Base Programs Analyses and Policies Work Group or to the contact person shown below.

Contact: Richard Chastain 205/257-6664

Date: September 19, 1996

TREATMENT OF AREAS IN WHICH AIR QUALITY TRENDS INDICATE THE RISK OF BECOMING AN AREA OF VIOLATION (AOV).

Background

The Clean Air Act divides the country into attainment, nonattainment and unclassifiable areas. Attainment and unclassifiable areas have very minimal requirements under the Act, regardless of how close they may be to nonattainment status. Once an area slips into nonattainment, however, it carries the stigma associated with that designation and is subject to difficult, and in many cases unpopular, requirements for planning and implementing a control strategy to attain the National Ambient Air Quality Standard (NAAQS). Among other elements, the plan must address emissions from existing sources and offset and more prescriptive control technology requirements for siting new sources.

The premise of this issue paper is that it is preferable for areas that are not violating a standard, but are in danger of doing so, to act affirmatively to avoid further deterioration in air quality that would result in designation as a nonattainment area or area of violation (AOV) Actions taken to avoid nonattainment -- such as "ozone action days" on which drivers and businesses voluntarily take actions to reduce their ozone precursor emissions -- are often more cost-effective than the prescriptive measures associated with nonattainment. In addition, they tend to educate the public about its role in contributing to air pollution and the role that individuals can play in reducing it, concepts that become increasingly important for the public to accept as standards become more stringent. Moreover, not permitting air quality to degenerate to the point that a violation of the standard occurs is obviously desirable from a public health perspective. It may also be appropriate for such areas to begin acquiring data and performing

studies that could later be necessary for compliance planning. Even though states can, and in some cases do, adopt proactive measures, this paper discusses concepts that could be developed into a more formalized policy to encourage such actions.

Before States (or broader planning areas such as potential areas of influence (AOIs)) can undertake measures to avoid new AOVs, however, they must be aware of those areas that are at risk of violating the standard. EPA's consideration of a range between the second highest and fifth highest concentrations in connection with a revised ozone standard suggests that the Agency believes that identification of areas that risk becoming AOVs is desirable. EPA has not, however, suggested how such areas should be treated.

The discussion below addresses how areas that are tending toward AOV status could be identified (including consideration of EPA's "in the range" approach) and what type of response should be taken in such areas (or in the broader anticipated AOI).

I.	Identification of Areas Tending Towards AOV Status

a.	How should areas tending towards AOV status be identified?

Before States or potential AOIs can act affirmatively to avoid new AOVs, they must be aware of areas in which the air quality is approaching a NAAQS violation. There appear to be three basic approaches to identifying such areas.

OPTION 1:	Track how close an area s monitoring data places it to the criterion for a NAAQS violation.

Under the present ozone standard, an area is in nonattainment if it records four exceedances in a three year period. An area could be identified as at risk of violation at some less stringent combination of exceedances and years. If a concentration-based standard is adopted, a similar but less stringent concentration-based variation could developed for use in identifying areas at risk. EPA's 2nd/5th highest concentration form for a revised ozone standard would be an example of this approach in which the fifth highest concentration average is the trigger for becoming an AOV while the second highest concentration average determines whether an area is at risk of becoming an AOV. An alternative approach would be to look at whether the concentration level for the NAAQS is repeatedly approached rather than focusing on the number of times that the concentration is exceeded.

While tracking nearness to the cutoff for identification as an AOV is relatively simple, this option does have some limitations. This approach would provide some warning that an area is in danger of becoming an AOV but that warning may not be sufficiently in advance for the area to take actions that would avoid the violation. In addition, this approach would not be likely to identify areas which are not in immediate danger of violating the standard but may nevertheless be trending that way. Finally, this option does not take into account the effect of meteorological variability on attainment status.

OPTION 2: Track air quality, emissions trends, and meteorological effects.

Methods have been developed in the context of the present ozone NAAQS that attempt to account for meteorological variability in projecting future air quality. Such approaches may allow development of a better picture of the underlying trends in air quality and thus enhance understanding of whether an area is truly tending towards a NAAQS violation or only appears to be approaching AOV status as a result of unusual meteorological conditions.

Of course, even if a measured exceedance of the standard level is due to a rare meteorological event, it could -- under EPA's present policies for implementing NAAQS -- be the basis for an AOV designation. The concept of "too close to call" was developed to address this problem. One option might be to apply a test for "too close to call" to determine whether an area with a measured standard violation should be considered to be an AOV or should be treated as tending towards AOV status. Another approach could be through use of a natural or exceptional events policy that would permit discounting of truly rare or exceptional events in making AOV determinations. Recommendations regarding such measures are beyond the scope of this paper but could be requested from the Science and Technical Support Work Group.

OPTION 3: Rely on a combination of these methods.

Looking at trends in air quality and emissions might provide advance warning that an area is approaching AOV status. Tracking nearness to the criterion for AOV status, however, would allow one to determine how critical the need for intervention has become.

RECOMMENDATION:

Based on the points discussed above, the work group s preliminary recommendation is Option 3.

b.	Who should be responsible for identifying areas that are tending towards AOV status?

There are three options for responsibility for identifying areas tending towards AOV status.

OPTION 1:	Identification of areas tending towards AOV status could be left to the discretion of the States and local air pollution authorities.

This option essentially represents the status quo. It has the advantage of imposing no new regulatory requirements. However, States without a nonattainment history may not be motivated to examine air quality trends and thus may not identify areas that are at risk of becoming an AOV until it is too late for them to take preventative measures. A strong recommendation from EPA that States track closeness to an AOV status -- perhaps with guidance on options for doing so -- might serve to alert States that do not presently do such tracking as to its value.

OPTION 2:	A regulatory requirement could be imposed for State or local air pollution authorities to develop programs to examine air quality trends to identify areas that may be tending towards AOV status.

This option would emphasize the importance of examining air quality trends, but could leave the States with a great deal of flexibility in their individual programs. For example, States could be left with discretion concerning the method used in examining trends or could decide whether to track some areas more closely than others. Alternatively, more prescriptive requirements for the States could be adopted, although, unless very carefully crafted, this could require burdensome tracking exercises in some cases where there is little likelihood of violation.

OPTION 3:	EPA could identify areas tending towards AOV status.

Under this option there would have to be a single national approach for judging when an area should be deemed to be at risk of becoming an AOV. This option is essentially the one that is captured by EPA's 2nd/5th highest concentration option for a revised ozone standard. It differs from a prescriptive state program under Option 2 primarily in whether the analytical burden is placed on the State or Federal government.

RECOMMENDATION:

Based on the points discussed above, the work group s preliminary recommendation is Option 1.

II.	Response Options for Areas Tending Towards AOV Status

Identification of an area as one that is tending towards AOV status could lead to four types of response:

OPTION 1:	States (and potential AOIs) could be allowed discretion concerning the appropriate response.

This approach would leave areas with the option of doing nothing, adopting voluntary measures, or adopting mandatory measures. The option would allow all areas within the potential AOI to take action, but if not all areas chose to do so, voluntary actions could be taken in portions of the potential AOI. This approach is most consistent with the idea that the area is presently attaining the federally required level for air quality. It is also consistent with the largely voluntary measures that some States and nonattainment areas have adopted for areas that have been identified as close to the line of ozone nonattainment and would recognize State efforts in this regard.

OPTION 2:	States could be required to develop a contingency plan that would take effect if an area were to become an AOV but leave to the State (and the potential AOI) discretion whether any additional measures should be taken to prevent the area from becoming an AOV.

This approach would minimize the time between an area becoming an AOV and the imposition of additional control measures. It would, however, impose a significant planning burden for an attainment area. It would potentially place the entire burden of contingency planning on an individual State. One variation that would avoid placing an unfair burden on a single state would be to require identification of a potential AOI and contingency planning for the entire potential AOI. However, the burden of formally identifying an AOI for an area that is not an AOV might be considered excessive.

OPTION 3:	States (and potential AOIs) could be required to implement specific measures aimed at preventing the area from becoming an AOV.

This approach comes close to transforming an area that has been identified as tending towards a standard violation into a de facto AOV. If the concept of AOV/AOI were adopted, this option would seem to pose the choice of identification of an AOI for an attainment area or place the burden of implementing required measures on the State (or States) in which the potential AOV was located.

OPTION 4:	EPA could provide States with incentives for adopting particular measures in areas that are determined to be at risk of violating a standard.

Even a purely discretionary program for avoiding new areas violating the standards, such as provided under Option 1, could place additional short-term burdens on the States. To encourage effective discretionary programs, in spite of these burdens, while at the same time avoiding new regulatory requirements, EPA could provide incentives to States that adopt voluntary programs that satisfy the Agency. For example, EPA could indicate that if the State will pursue voluntary emission reductions measures in conjunction with an effort to develop the data on emissions and speciation necessary to identify an AOV should a violation occur, EPA would not identify the area as an AOV for a specified period of time (e.g. 3 years). This would allow the State to establish whether voluntary measures are adequate to attain NAAQS while minimizing the planning time should a designation as an AOV be necessary.

This approach is consistent with the flexible attainment area approach currently being used in parts of Texas, under which the state has provided EPA with a list of specific measures that it will take to avoid NAAQS violations and contingency measures that will be followed if a violation occurs. In exchange for this burden, EPA has agreed not to designate an area as nonattainment if those measures (including any appropriate contingency measures) are implemented.

RECOMMENDATION:

Based on the points discussed above, the work group s preliminary recommendation is Option 4.