Reasonable Further Progress (RFP) Call

Wednesday, April 23, 1997

2:30 - 3:30 pm

Attendees:

Cyril Durrenberger	TNRCC

David Sanders	U.S. EPA/OPSG

John Silvasi	U.S. EPA/OPSG

Bob Stallings	U.S. EPA/OPSG

Steve Ziman	Chevron

Contractor Support:

Stephanie Bowens	SAIC

Summary of the Call

John Silvasi asked the group if it would be okay to record the phone conversation, such that she could make a more accurate accounting of the minutes. (Note: All parties agreed to allow the conversation to be recorded).

John Silvasi began the call with a recap of the meteorological variability call, which was held earlier in the day. Mr. Silvasi started by reiterating the questions that the group on this issue.

Question #1:	The "customized" RFP process contemplates an iterative process where certain air quality metrics will be analyzed at pre-determined intervals to determine if the emission reduction programs are producing the desired air quality changes (i.e., is the area headed for attainment and, if so, at the planned rate?). Question: What guidance can the STSWG provide with respect to the appropriate length of time needed to determine if a true air quality trend is taking place or whether fluctuations in air quality are random noise. Obviously, it is preferable to know whether or not emissions reduction programs are working in the right direction and at the desired rate as soon as possible but, it is also understood that 1 year of air quality data is probably not sufficient to make such judgements about the efficacy of an emissions reduction program. What guidance can the STSWG provide with respect to an appropriate interval for assessing changes in air quality for ozone? For PM-fine?

John Silvasi indicated that this latter issue was one that the meteorological variability group also wanted to explore.

Steve Ziman stated that he thought this group was supposed to address what we thought would be appropriate metrics?

John Silvasi indicated that this was absolutely correct, but that he had not gotten to that question yet. Mr. Silvasi continued with the questions from the NRSWG.

Question #2:	Attached is a list of air quality metrics that might be suitable for assessing whether or not changes in air quality at the "pre-determined intervals" described above are truly taking place. What guidance can STSWG provide regarding which of these metrics are reasonable from a science perspective, recognizing that the ultimate of this customized RFP process is to produce attainment by the attainment date? Are there alternate metrics that should be used in lieu of the ones listed here? Does the STSWG have a preference - based on scientific principles - for any of the metrics listed here and other metrics the STSWG proposes? For the emission reduction metric, does the STSWG agree that emission inventories are the preferred metric? If not, what other emission reduction metrics should be used and in what priority?

In evaluating the metrics in this question, the STSWG should account for the following considerations:

Technical Considerations:

a.	Uncertainty - all of the metrics (emissions, air quality, etc.) have a degree of uncertainty, and some of the metrics build on other metrics (i.e., population exposure builds on air quality modeling and emission projections).

b.	Data Requirements - are the necessary data available to drive the metrics; are the data needs so substantial that only the most sophisticated agencies could make use of the metric?

Uses of the Metric:

a.	Prospective (planning) versus Retrospective (tracking) - some metrics may be more suitable for retrospective application, rather than prospective application.

b.	Trading - does the choice of RFP metric influence the choice of metric used for trading?

c.	SIP Revisions - is the RFP metric precise enough to determine whether Section 110(l) on plan revisions is violated?

Tiered Metrics:

Given the above issues, should there be a hierarchy or tiering of metrics, for instance:

a.	Primary Metrics - could be emissions and air quality (in the narrow sense), which all areas would project and track; these metrics could be used to set the minimum requirement for progress, and also provide the common yardstick for "expeditious" progress and attainment.

b.	Secondary Metrics - to be used for further comparison or optimization of the control path. These would be optional and might include cost- effectiveness, population exposure, environmental justice, and so on.

John Silvasi stated that there was a third question, however, this question was being dealt with by the meteorological variability subgroup. He indicated that the list of metrics was also included with this material, and that it had been broken down as follows:

-	emission reduction metrics

-	air quality metrics

-	population-weighted exposure metrics

-	land-weighted exposure metrics

-	persistence weighted metrics

-	PM-specific metrics

-	End-loaded strategies

-	Time integrated concentrations

Mr. Silvasi continued that under each of these categories, there were one or more metrics listed as examples. He said that these examples were primarily the result of the brainstorming sessions that were held here in RTP back in March of this year.

Steve Ziman indicated that he and Cyril Durrenberger had been discussing the fact that some very broad things had been thrown into questions 1 and 2. He indicated that there were several discussions about this at the Falls Church, Virginia meeting in April. He suggested that the group look for the things that could be agreed upon up-front, and proceed to move forward. He said that he believed that were a number of issues that this group would adopt up-front, and thus we could avoid wasting time discussing them any further. For example, the use of an emissions metric as the primary driver is simply not appropriate, because this simply modeled what we had done since the 1990 CAAA. Along these same lines, the group decided that the pursuit of an air quality metric was the desirable path to take on this issue. Mr. Ziman continued that he thought this group could identify several air quality metrics which could be explored further. He reminded the group that he did not say a single air quality metric, but a set of air quality metrics. He concluded stating that he had shared these ideas previously with Mr. Durrenberger and Mr. Silvasi.

John Silvasi agreed, and mentioned the paper that Cyril Durrenberger had co-authored with Jim Smith.

Steve Ziman suggested that the group first discuss the metrics outlined in Mr. Durrenberger's paper, and the we could proceed directly to the issue of prospective versus retrospective. Mr. Ziman asked Mr. Durrenberger to go over his concepts at this time.

Cyril Durrenberger said that the metrics he would be discussing could be used for both prospective and retrospective analyses. Mr. Durrenberger said he would go through each of the five issues in sequence.

•	First, there is concern about the time required within which to establish a realistic or acceptable trend. Mr. Durrenberger suggested that perhaps a minimum of three years of data was necessary; but, most likely a period of 5-6 years would be preferable.

•	Second, we should apply the adjustments that David Chock has been discussing (e.g., the t-test) so that some of the variability can be removed from the system.

•	Third, there needs to be a tool that allows the design value to be tracked.

•	Fourth, exposure above a certain level should also be tracked. This would be an areal exposure. In the paper I have written with Jim Smith, this level is considered to be the integrated time over 80 ppb over a given spatial domain.

•	Fifth, the concept of population exposure needs to be addressed. However, this could be problematic for certain, which do not have a sufficient monitoring network to support such monitoring requirements.

Mr. Durrenberger suggested that most of these metrics could be used for a planning processing; however, he was concerned about its applicability to tracking procedures. He continued that population exposure in its simplest form would look at the percent of the population above a certain level (e.g., 80 ppb) of the standard. However, a more appropriate method would be to look at a population-weighted approach, which would involve a combination of metrics 3 and 4. This would result in a concentration above a threshold for a given number of individual hours (e.g., ppb-hours per person). At some point for certain areas, you will come to the line where further controls will no longer provide improvements to air quality. However, this line can change with time because of changes in control technology. The periodic nature of this metric would allow for the incorporation of new ideas into the process, and does allow for mid- course corrections if required to meet the attainment schedule. Thus, this approach allows both for planning and tracking, and they can be used effectively with numerical modeling techniques.

Steve Ziman stated that he would like to provide some clarification in terms of the design value metric. Mr. Ziman stated that one could look at the design value, but more importantly, other metrics should be looked at (e.g., areal or population exposure), because these newer metrics allowed the evaluation of both the temporal and spatial aspects of the surface ozone distribution. The design value concept is flawed, because it relates air quality to a single monitoring site/location. He concluded stating that the population method would be best, because the areal metric did not provide any indication of the concentrations where people actually were located.

Cyril Durrenberger agreed with Mr. Ziman, and indicated that the Lake Michigan area was a perfect example of this. In this case there was extremely high ozone out over Lake Michigan, but the population is all along the shore. Thus, in this case, you would high areal exposure, but rather low population-weighted exposure. Mr. Durrenberger also indicated that they see this problem in the Beaumont-Port Arthur, Texas area, where the highest ozone is offshore over the Gulf of Mexico. Thus, the design value metric is important, but the last two (e.g., areal and population exposure) would be the most critical ones.

Steve Ziman commented that the location of monitors was also very important in designing a population exposure network, based on some of the work done in California. When you start looking at interpolation schemes, a less dense network proves to be problematic; however, there has not been enough work done on this concept at this time to publish any siting criteria guidance. Basically, you should not represent more than 10% of the population by any one single monitor. You do not want to be in a situation where you use a single monitor to represent an entire urban core. Thus, Mr. Ziman cautioned the group to be very careful in the approach taken for this metric.

Cyril Durrenberger agreed with Mr. Ziman.

Steve Ziman stated that the other issues were being discussed in California at this time. For example, he stated that one issue that has arisen is whether door-step exposure is acceptable in regions where the capability exists to use an exposure model to generate these type of estimates.

Cyril Durrenberger replied that he could justify the use of door-step exposure estimates if the group would like to listen.

John Silvasi stated that at some point when this subgroup has something down in writing, he would first like to run this effort by EPA's health effects personnel, as well as the full STSWG membership, prior to releasing anything to the FACA. Mr. Silvasi also stated that Larry Larson from CARB should also review this effort, and perhaps begin to join this group on a regular basis for input.

Steve Ziman agreed with this approach.

Cyril Durrenberger also acknowledged his agreement, and stated that he would like to run this concept by some of his health effects personnel in the State of Texas.

Steve Ziman commented that are one or two other issues that he believed the group was in concurrence on, and that if the group would simply put them on the table, he believed we could move past them. First, Mr. Ziman stated that with regard to retrospective analyses, it was clear that there was the question of variability. He said this needed to be resolved such that we could look back at a trend and determine the following: (1) whether the changes that were observed in ozone concentrations at a given monitor were responding to the emissions reduction; and, (2) whether the rate of progress that was observed was not driven totally by meteorological variability. Mr. Ziman continued saying that we are now trying to deal with the issue of prospective, because the planning cycle basically attempts to identify one or more episodes that can be modeled that can be shown to be representative of meteorology that has been historically observed. As such, when we have developed SIPs, and tried to demonstrate, we have used these types of episodes. In adopting this approach, we have acknowledged that these are singular events, and do not represent long-term averages. In some respects, we are still left with these concepts, because we do not have the ability to model all episodes.

Cyril Durrenberger stated that one of the beauties of the iterative approach was to be able to take the monitoring data and do exactly what Mr. Ziman is talking about, and then to analyze why your planning process did or did not work as planned. Mr. Durrenberger stated that this iterative process would allow states to do a better job at what they were trying to do. He concluded saying that an iterative approach was the only process that would allow the states the flexibility to have mid-course corrections to make adjustments on critical issues that were simply not working.

John Silvasi agreed with Mr. Durrenberger.

Cyril Durrenberger reminded that attainment would not come over night. He reminded the group that there would be large areas where initial efforts would fail; however, the states would simply have to go back and try again using different strategies.

John Silvasi cautioned that the group needed to keep in mind that this group is addressing metrics, and that Cyril Durrenberger and Steve Ziman were also discussing the "off-ramp" process. Mr. Silvasi asked that these two issues be kept separate, even though there was a good deal of overlap.

Cyril Durrenberger stated that under this iterative process, there would the time where a state would say that "this is as far as we can go" towards implementing controls. All this really does is tie-in with the weight of evidence approach, and make the "bright-line" distinction a little more defined.

John Silvasi stated this issue also spilled over into the Issue Paper that STSWG and NRSWG are writing with Ted Russell.

Cyril Durrenberger stated this issue was also driving the SIP process as well, and as such, RFP was the glue holding a lot of this stuff together.

Steve Ziman said that some people within the RFP subgroup want to artificially have a construct that separates out areas that may be able to attain from areas that may not be able to attain. However, what we are talking about is a metric that would be equally applicable to both areas. In the SIP process, as you start your modeling, and make your sensitivity runs, you are going to start to identify exactly what it is that you want to look at in order to get your necessary reductions. This is essentially determining what percentage change from your base case that you need to achieve a relative change in ozone. In fact, what you would see was an output that looked very similar to isopleths. These outputs would not be your strategy, but they would bound the alternatives that you could try to get the required reductions. Thus, any agency that has to prepare a SIP, would have to go through this process. Thus, if you could not identify the necessary reductions, then this is where the question of the feasibility of attainment comes in. However, you would still be using the same approach to make the attainment determination, regardless of whether you could or could not make the necessary reductions to get to attainment.

Cyril Durrenberger suggested that design values be linked to population exposure. He suggested that was intention earlier, that the group look beyond the design value in determining an air quality metric.

John Silvasi said that he would like to see the contractor provide this information to EPA, and then the Agency could run this by Mr. Ziman and Mr. Durrenberger for comments and modifications. He stated that once the subgroup was satisfied with the document, then it could be presented to the entire STSWG.

Cyril Durrenberger stated that he was concerned that we had not addressed the emissions side of this issue yet.

John Silvasi stated that he was not concerned about this. He stated that he did not expect the group to solve everything in one or two calls. Mr. Silvasi commented that we would use an iterative process to reach our goals.

Steve Ziman stated that they way the questions were phrased reflected the diverse interests of the members of the initial RFP group. Mr. Ziman continued that he and Mr. Durrenberger did not feel that all the diverse opinions reflected in the questions deserved the same level of discussion, and thus he would be in favor of spending more time on some issues, and a good deal less time on other issues. The emissions metric has nothing to compare itself with. The air quality metrics demand emissions reduction if they are not to be masked by variations in meteorology.

Cyril Durrenberger said that he would agree with Steve Ziman, in that STSWG could not identify out to the 10th or 11th metric exactly the process that a given state needed to take. Mr. Durrenberger stated that each location would be different.

John Silvasi acknowledged that at some point the political process would take over, and that there would be some limit to STSWG input. However, Mr. Silvasi encouraged the group to get their inputs in early, and to contribute to the political process in a scientific manner.

Cyril Durrenberger responded that he thought we were doing this effectively with what we had done today. He suggested that he and Mr. Ziman take the rough draft of this call and work it into something more formal, and then begin to circulate it among STSWG.

Steve Ziman agreed with this approach. Mr. Ziman also stated that some of these other issues were bogus (e.g., trading). He said that he really did not want to spend a great deal of time on these type issues.

Cyril Durrenberger agreed saying that he thought the control strategies would geographic in nature and that the trading would be geared to these geographic regions. He said that these regions might be VOC-specific, high-level NOx, etc. Mr. Durrenberger stated that trading would be a very localized (e.g., case by case analysis) procedure.

Steve Ziman agreed, saying that the Agency would simply have to let local areas try certain programs, rather than having some prescriptive national guidance. Mr. Ziman stated that flexibility was a key element in this entire process. He stated that it was very unrealistic to make this an iron-clad policy.

Cyril Durrenberger reminded the group that we had to be careful not to make the policy so complex that it was totally unworkable. He concluded that you simply could not account for every single case that would crop up.

John Silvasi thanked everyone for their participation, and said he would schedule a call for later next week.