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 12, 1996

TREATMENT OF AREAS IN WHICH AIR QUALITY TRENDS INDICATE THE RISK OF FUTURE STANDARDS VIOLATION

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. 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. 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 a more formalized policy to encourage such actions.

Before States can undertake measures to avoid new areas of violation, 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 violating the standard is desirable. EPA has not, however, suggested how such areas should be treated.

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

I.	Identification of Areas Tending Towards Standards Violation

a.	How should areas tending towards standards violations be identified?

Before States can act affirmatively to avoid new violation areas, the States must be aware of areas in which the air quality is approaching a standard 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 standard 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 determines compliance while the second highest concentration average determines whether an area is approaching violation.

While tracking nearness to the nonattainment cutoff is relatively simple, this option does have some limitations. This approach would provide some warning that an area is in danger of becoming violating the standard but that warning may not be sufficiently in advance for the area to take actions that would avoid that 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 and emissions trends.

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 trends in air quality and thus enhance understanding of whether an area is truly tending towards a standard violation or only appears to be approaching violation 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 can -- under EPA's present policies for implementing NAAQS -- be the basis for a nonattainment 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 have violated the standard or should be treated as tending towards a violation. 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 attainment decisions. 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 nonattainment is a possibility. Tracking progress towards the criterion for a violation, however, would allow one to determine how critical the need for intervention has become.

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

There are three options for responsibility for identifying areas tending towards nonattainment.

OPTION 1:	Identification of areas tending towards a standard violation 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 violating a standard until it is too late for them to take preventative measures. A strong recommendation from EPA that States track closeness to a violation -- 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 standard violations.

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 standard violations.

Under this option there would have to be a clear national method and standard for judging when an area should be deemed to be at risk of becoming nonattainment. 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.

II.	Response Options for Areas Tending Towards Violations

Identification of an area as one that is tending towards standard violations could lead to three types of response:

OPTION 1:	States could be allowed discretion concerning the appropriate response.

This approach would leave States with the option of doing nothing, adopting voluntary measures, or adopting mandatory measures. 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 States have adopted for areas that have been identified as close to the line of ozone nonattainment and would recognize State efforts in this regard. Finally, this approach would be viable even if the concept of AOV/AOI replaces nonattainment areas. Not only the State in which the potential AOV is located but even potential AOIs might be willing to adopt voluntary measures to avoid becoming embroiled in a mandatory regional planning process with mandatory measures to follow.

OPTION 2:	States could be required to develop a contingency plan that would take effect if an area were to cross over into nonattainment but leave to the States discretion whether any additional measures should be taken to prevent the area from slipping into nonattainment.

This approach would minimize the time between an area becoming nonattainment and the imposition of additional control measures. It would, however, place a significant planning burden on a State with regard to an attainment area. Indeed, if the AOV/AOI concept were adopted, it would either require the highly complex process of identifying an AOI in which contingency planning was required or place the entire burden of contingency planning on the individual State.

OPTION 3:	States could be required to implement specific measures aimed at preventing the area from becoming nonattainment.

This approach comes close to transforming an area that has been identified as tending towards a standard violation into a de facto area of violation. 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 with a purely discretionary program, a program for avoiding new areas violating the standards could place additional short-term burdens on the States. To encourage effective programs in spite of these burdens while at the same time avoiding new regulatory requirements, EPA could provide incentives to States that adopt 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 Area of Influence should a violation occur, EPA will not identify the area as one violating the standard for a specified period of time (e.g. 3 years). This would allow the State to establish whether voluntary measures are adequate to attain the standard while minimizing the planning time should a designation as nonattainment (or area of violation) be necessary. This approach is consistent with the flexible attainment area approach currently being used in parts of Texas.