OPTIONS FOR DESIGNATING PM-fine AREAS

This is a preliminary document prepared by EPA supporting the Federal Advisory Committee Act (FACA) Subcommittee. This is a draft issue paper which is subject to further discussion with the FACA Subcommittee. The following document reflects comments received and the discussion heard at the October 1996 Subcommittee meeting in Dallas, TX.

November 12, 1996 Revision #2

Interested people should forward their comments to:

Gary Blais representing EPA@ 919-541-3223, or Internet:"blais.gary@epamail.epa.gov"

BACKGROUND

EPA is currently considering potential revisions to the NAAQS for particulate matter to include a new standard for fine particulate matter. Fine particulate matter is defined as particulate matter with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers (hereafter referred to as PM2.5). The form of the new standard is still being discussed and EPA could approach the ambient data requirements for the new standard in the same manner as for the PM-10 standards. That is, three years of ambient data will be needed in order to determine whether or not areas are attaining the new NAAQS. Three years of data are considered necessary to provide a stable target for determining the air quality status of an area and to minimize the possibility of areas slipping in and out of attainment.

Previous option papers circulated amongst the various FACA workgroups have dealt with the designation issue. Notably, the July 25, 1996 joint workgroup options paper prepared by representatives of the Base Programs Analyses and Policies, National and Regional Strategies, and the Science and Technical Support Work Groups. This paper discusses the designation issue in great detail and should be referred to for a full understanding of the "area of violation" concept that will be referred to later in this paper. Briefly, "areas of violation" (AOV) describe those areas in which violations of the standard are observed; and "areas of influence" (AOI) describe those areas which potentially contribute to the violations. 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 be based on sound technical information and science, identifying the area that contains sources or groups of sources that potentially contribute to the exceedance of the ambient standards in the associated AOV.

The purpose of this paper is to address the issue of the timing of PM2.5 designations which has not been expressly dealt with as yet. Early on in the PM NAAQS review process all the major PM stakeholders conveyed their preference for using three years of ambient monitoring data rather than a statistical approach which predicts PM2.5 concentrations from a ratio of PM2.5 to PM10 using a small ambient air monitoring dataset where both size fractions were available. Their concerns stem from the EPA's decision in 1987 to use a similar approach for the PM10 NAAQS designations, and is based on the uncertainties associated with the statistical approach and the resulting designations for PM10. Some areas were designated PM10 nonattainment based on the statistical probability approach even though they never violated the NAAQS, while other areas with low probabilities did subsequently violate the standard, but were not initially designated nonattainment. Another concern with using a statistical approach for PM2.5 is its regional nature and the potentially large secondary component. PM10 is generally not as reliable a surrogate for PM2.5 as TSP is for PM10. In many areas of the country the PM10 concentrations are dominated by a large coarse particle component. Studies have also shown that PM2.5 concentrations vary by season as compared to PM10 concentrations in the same areas. For these reasons, the stability and accuracy of a statistical approach based on ratios is questionable.

The FACA workgroups recommended and the Subcommittee supported (in the AOV/AOI issue paper) that the designation of PM2.5 areas be based on a minimum of two years of ambient monitoring data. As the workgroups continue to explore options presented in the integrated implementation issue paper, several questions arise. How will the requirement for two years of PM2.5 data affect the Subcommittee's desire to identify integrated control strategies for ozone, PM2.5, and Regional Haze? Should ozone designations be delayed so that the planning process for ozone and PM2.5 will be synchronized? Is it important for them to be on the same schedule, or should we rethink our recommendation that only monitoring data be used to designate PM2.5 areas? Is the use of monitoring data still a critical issue as we move from the current Air Quality Management structure approach to the AOV/AOI approach. As stated in the September 19, 1996 AOI approach issue paper, and the Designations issue paper of July 25, 1996, the identification of an AOI initiates a planning process. This process includes: the development of a comprehensive emissions inventory, identification of modeling tools, and collection of ambient data to accurately characterize the AOI so that appropriate control strategies can be developed. The planning process could also include the adoption of national control strategies to provide for emissions reductions during the interim period between the identification of planning regions under the AOI concept, and the gathering of three years of data needed to make accurate nonattainment or AOV designations. Since the identification of AOV's doesn't immediately require any controls, is the strict use of monitoring data still a critical issue?

It should be recognized that there are fundamental Clean Air Act (CAA) requirements tied to designations. For example, once a NAAQS is promulgated, within 3 years EPA must designate areas nonattainment that do not meet the new NAAQS. This fact presents several logistical problems if EPA relies solely on monitoring data to make designations. It takes time to develop a monitoring method, build the monitors, and deploy them across the country in a logical manner. EPA currently has no federally endorsed method for monitoring for PM2.5 to rely on. Once a method is developed and endorsed, the monitoring instruments must be manufactured. After this is accomplished, the monitors must be deployed. All of these tasks are time consuming and expensive. Adequate funds are not expected to be available to build and deploy an extensive network of monitors that ideally EPA would like to see, at least not within the three years EPA has under the CAA to make designations. At best, a fully deployed network of 1200 monitors will be in place by December of the year 2000 (see time line graph below). However, EPA has only until June of the year 2000 to complete the designation process. To do this properly would require that PM2.5 monitoring data from the entire national network be available for the years 1997-1999. However, the new network will only be partially deployed starting in January 1997, and the data collected from the entire network will not be available until April 2003.

After reviewing the Subcommittee's comments and those from other members of the FACA workgroups on the previous version of this options paper dated October 21, 1996, this new version was drafted to respond to those comments. The goal of this draft is to narrow the list of options with the hope that a clear favorite will emerge. The comments ranged from those favoring an immediate designation upon promulgation based on the ratio or statistical probability method, to those favoring immediate designation based on the unclassifiable method. These methods represent the endpoints of the range of comments and both received about as much support as criticism. There appears to be some consensus towards a middle ground approach that provides a balance between environmental and public health protection, and using what most commenters feel is the best most reliable indicator of attainment status, monitoring data. Therefore, the following options involve using the most monitoring data available by June 2000 to make an interim designation, and require that control strategy development go forward without delay.

Again, they are not meant to represent an all inclusive, comprehensive list of options, but are circulated to stimulate discussion and to solicit Subcommittee comments, and a recommendation on how to proceed.

1. ROLLING METHOD

▪	Preliminary designation at promulgation of the new NAAQS for all areas would be based on all available information . As soon as two years of data are available from the sites EPA has targeted first because of high population exposure, an interim designation of either attainment or nonattainment could be made. Areas could then receive final designations after they gather three years of data. An interim nonattainment designation would mean that control strategy development planning must begin immediately. As more sites come on line this process could continue in a rolling manner. For all other areas where enough data will not be available by June 2000 (the statutory deadline for designations), the preliminary designation made upon promulgation of the new NAAQS will continue to remain in force until at least two years of monitoring data is available to make an interim designation. Once these areas have gathered three years of data, final designations could be made.

PROS:	Decision based on actual data.

Satisfies CAA requirement to designate within 3 years. Control strategy development moves forward.

Provides monitoring incentive.

CONS:	Introduces a new interim status concept based on only 2 years of data, may be challenged on legal grounds.

Interim designations based on only 2 years of data. Not as stable and accurate as an estimate based on 3 years of data.

Control strategy development may be misdirected.

2. EARLY RESPONSE METHOD

▪	Uses the statistical probability approach (or other agreed upon approach) described above to determine areas which have a high probability of violating the standards. Those areas would be selected for accelerated monitoring so that 3 years of monitoring data will be available sooner. Accelerated monitoring requirements would include 1 year of PM-fine monitoring augmented with speciated monitoring. At the end of 1 year, if the monitoring data show a violation, a nonattainment or AOV designation is made, and the area has the requisite speciated data to initiate the planning process (i.e., determination of AOI or SIP). This process would be linked to a time certain end point for all areas (e.g., 2009) independent of the year of the AOV designation. For areas not determined to be high probability and not included in initial "early response": EPA could establish exceedance criteria which based on 1 year of monitoring, would then trigger "early response" monitoring in the second year. Time certain attainment date could be an incentive for early monitoring (as delayed monitoring could lead to compressed planning/implementation process).

PROS:	Early action for areas with the worst air quality. Earlier response to public health concerns.

Early speciation to speed planning process.

No penalty or disincentive for early detection and response.

Relies on monitored data for redesignation, satisfies CAA requirement in a timely manner.

CONS:	Time certain attainment date (not fixed to redesignation date) may not be consistent with CAA.

AOV's not initially determined to be "high probability" would not have early response.

Probability-based selections could be wrong.

INTEGRATION IMPLICATIONS

Finally, EPA is exploring the linking of PM, O3, and RH designations together consistent with the integrated implementation approach that the Agency outlined at the September 1995 Subcommittee meeting. However, it must be recognized that in doing so the potential exists for delaying ozone designations for 2 or 3 years, delaying implementation of new control strategies, and for potentially prolonging the life of the interim implementation policy.