DRAFT February 3, 2015 

Pre-Meeting Materials for the EPA-FLM-RPO-States-Tribes Meeting 

on the Future of the Regional Haze Program

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GUIDANCE TOPICS

Topic III: The URP and RPG Framework

Relevant Background 

The current RHR requires states to determine 2000-2004 baseline manmade visibility

impairment conditions for the 20% best and 20% worst days, and to determine natural visibility

conditions for the same two sets of days.

States project their visibility conditions for the end of the planning period for the 20% best and 

20% worst days using a photochemical air quality modeling system to project the net effect of 

their long term strategy of emission controls. The projected values are referred to as reasonable 

progress goals (RPGs).

The RPGs are used in later progress reports as points of comparison to most recent visibility 

conditions. Progress reports are required to include a state determination of whether the SIP is 

adequate to ensure that the progress goals will be achieved by the end of the planning period.

The existing URP and RPG framework for setting RPGs and tracking progress towards those 

goals is susceptible, at some Class I areas, to substantial year-to-year variability due to natural 

events with significant visibility impacts, such as large wildfires and dust storms. This is 

illustrated for one Class I area in the following figure of annual deciview values for the 20% 

worst days. This variability is dampened but not always removed by the use of a 5-year moving 

average.

In addition, because the analytical procedure for setting RPGs does not distinguish between 

domestic and international anthropogenic emissions, the current RPG framework can mask 

progress that a state air agency may be making.

Virtually all stakeholders were concerned and recommended that the EPA provide rule changes 

or guidance for visibility progress metrics that focuses on reducing controllable emissions. In

response to this feedback, we intend to issue guidance that focuses visibility progress metrics on 

reducing U.S. anthropogenic emissions.
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Pre-Meeting Materials for the EPA-FLM-RPO-States-Tribes Meeting 

on the Future of the Regional Haze Program

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Issues

A. Issue Statement – Addressing the Impact of Natural Events

Questions

1. Is it appropriate to remove (or possibly adjust) days that are dominated by natural events 

from the 20% worst set of days, for event types whose impact varies a lot from year to 

year, as a way of making more evident any progress that has been and will be achieved 

by control of anthropogenic sources? Are such event types limited to wildfires and dust 

storms, or are other event types of concern?

2. After internal discussion and close reading of the RHR as a whole, including definitions, 

the EPA workgroup currently believes that removing (or possibly adjusting) days that are 

dominated by natural events is consistent with the existing Regional Haze Rule (RHR). 

Do you agree, or do you believe the RHR would need to be amended to allow this? If you 

agree that the RHR allows this, should the rule be amended for clarity on this issue? Here 

are relevant definitions from the RHR:

Visibility impairment means any humanly perceptible change in visibility (light 

extinction, visual range, contrast, coloration) from that which would have existed 

under natural conditions.

Most impaired days means the average visibility impairment (measured in 

deciviews) for the twenty percent of monitored days in a calendar year with the 

highest amount of visibility impairment.

3. What are the most important of the following factors that EPA and others could consider 

when developing a method for removing (or possibly adjusting) days with poor visibility

due to natural causes?

o Good science.

o Consistency.

 Should there be one common, consensus method across Class I areas and 

states, possibly with area-specific details? Or, should the state with the 

Class I area pick the method?

 Is consensus and commonality more important among the western states 

because they have closely spaced Class I areas and many fires, compared 

to the east?

o Resource burden (data, labor, and calendar time).

 Because every Class I area will be tracked, every IMPROVE site-day will 

need to be assessed, over the next several decades. This is different than 

for exceptional events for purposes of the NAAQS.

o Objectivity. How important is it that the assessment of an IMPROVE site-day be 

objective once the method and criteria have been established, versus it involving 

an element of judgment such as in a weight-of-evidence approach?

4. Should the approach aim (i) to remove the influence only of natural events that are highly 

irregular in their impacts in different years (which may be sufficient to eliminate highly 

irregular trend lines), and then (ii) rank the days to identify the 20% with the highest light 
DRAFT February 3, 2015 

Pre-Meeting Materials for the EPA-FLM-RPO-States-Tribes Meeting 

on the Future of the Regional Haze Program

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extinction (even though these generally would not be the 20% most impaired by 

manmade causes, strictly speaking)?

 If this is the preferred approach, then identifying site-days with visibility

impairment from highly irregular natural events might rely on a threshold 

for determining that a site-day has been sufficiently affected by such 

natural sources to merit special treatment. How should a threshold(s) be 

picked?

 In this approach, once a site-day has been identified as having been 

dominated by an irregularly occurring event such as a fire or dust storm, 

should that day be removed completely, or should the monitoring data for 

that day be adjusted by replacing some PM component concentrations 

with default values? Removing days has the potential of changing the 

apparent transport linkage between manmade sources and Class I areas.

 How should the default values be picked? Is the IMPROVE protocol for 

data substitution when valid filter data is not obtained appropriate? 

 If a day is removed, should the next-ranked day be brought into the 20% 

most impaired group?

5. Or, should the approach aim (i) to determine natural and manmade contributions to light 

extinction for every day, and then (ii) rank the days to identify the 20% with the highest 

manmade impairment?

 This approach directly addresses the CAA goal of reducing manmade 

visibility impairment. 

 If this is the preferred approach, a method would be needed to allocate and 

adjust PM components between natural and manmade sources.

6. Given the goal of focusing the framework on control of manmade emissions, the factors 

for consideration listed in Question 3, and the two possible approaches for removing or 

adjusting IMPROVE data, what would be the most appropriate analytical method, under 

each of the two approaches? Possible analytical methods that have been discussed within 

EPA and considered to have some promise include the following:

o Using fixed thresholds (possibly site-specific but the same for all years) for 

carbon, fine soil, and coarse PM to identify site-days as having been dominated 

by fires or dust storms, which are the most obvious irregularly occurring natural 

sources, and substituting default IMPROVE values for these PM components.

o Using trajectories and emissions inventories to allocate monitored PM species 

concentrations among natural sources (including fires) and manmade sources.1

o Regional scale air quality modeling with source apportionment based on emission 

inventories including fires.

7. Is it possible and appropriate to distinguish between wild fires and wildland prescribed 

fires when removing (or adjusting) days from the 20% worst set? Is it a significant 

problem if we cannot recommend or require a practical method for making this 

distinction, or is it a de minimis departure from the ideal?

 

1

Some meeting attendees may already be familiar with exploratory work of this nature by Scott Copeland.
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Pre-Meeting Materials for the EPA-FLM-RPO-States-Tribes Meeting 

on the Future of the Regional Haze Program

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8. Is there a useful role for pollutant-specific glide paths as a supplement to the glide path 

analysis required by the RHR, either as interpreted in the first planning period or 

reinterpreted as described in these questions?

B. Issue Statement – Non-U.S. Anthropogenic Emissions

Stakeholders have also expressed concern that monitored most recent period visibility

impairment can include the effects of non-U.S. emissions which no state can influence, 

yet the 2064 natural conditions end point does not include such impacts, at least in 

principle.

Questions

1. If EPA were to propose to change the RHR in this area so that impacts of non-U.S. 

anthropogenic emissions were consistently included or excluded from elements on the 

URP and RPG framework, which is not currently certain, how could these impacts be 

estimated, on a consistent basis?

o If these impacts were allowed to be added to the 2064 end point of the URP line, 

how could global scale modeling be used to estimate the impacts of non-U.S. 

anthropogenic emissions? 

2. Assuming that without a rule change the impact of anthropogenic sources outside the 

U.S. cannot be added to the 2064 end point of the URP line, how else can guidance help 

air agencies, and the public who comment on draft SIPs and on progress reports, focus on 

progress being made in the control of anthropogenic sources within the U.S?

o For example, would it be helpful if EPA recommended that SIPs and progress 

reports include a second, informational-only URP diagram that is based on the 

2064 end point including impacts from non-U.S. anthropogenic sources?

C. Issue Statement – Natural Conditions and 2000-2004 Baseline Visibility Conditions

Modifying the way that baseline visibility on the 20% most impaired days is determined, 

by removing (or adjusting) some of the days that have the worst 20% overall visibility, 

would raise the issue of consistency between the resulting metric tracked for progress 

reports, the 2000-2004 baseline visibility conditions, and natural conditions.

Questions

1. Should baseline conditions (the 2000-2004 starting point for the URP line), projected 

2028 air quality conditions, and natural conditions (the 2064 end point of the URP line)

to the extent possible be re-determined for each Class I area on a basis that is consistent 

with the exclusions used for the most recent period? 

o For example, consistency between the 2028 projection (the RPG) and the metric 

that is tracked on a rolling 5-year average basis might be improved by similarly

removing from the modeling base year, for example 2014, any days that were 

similarly affected by natural events, before calculating and apply relative response 

factors.

o Assuming that the approach in Question 4 above (removal/adjustment only of 

days affected by very irregular natural events) is followed, consistency might also 

mean that estimates of natural conditions should be revised to represent natural 
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on the Future of the Regional Haze Program

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conditions except for the influence of such irregular natural events, i.e., natural 

conditions in the absence of such irregular natural sources would need to be 

estimated. This would require a reconsideration of the 20% worst natural visibility

conditions that were used in the first planning period because at least in concept 

these values were meant to reflect contributions from all natural sources including 

irregular extreme events.

o Assuming that the approach in Question 5 above (allocation of all light extinction 

between manmade and natural sources on all days) is followed, then in concept 

the natural visibility conditions that were used in the first planning period would 

be appropriate for use.

2. What other consistency issues need to addressed, and how?

3. More generally, should the values used for natural conditions in the SIPs for the first 

planning period (those recommended by the “Natural Conditions II” workgroup) be 

reconsidered? How should this be approached?

D. Issue Statement – Translating the Long Term Strategy into Reasonable Progress Goals

This is the topic of the EPA guidance document “Modeling Guidance for Demonstrating 

Attainment of Air Quality Goals for Ozone, PM2.5 and Regional Haze,” a draft revision of 

which is currently available for comment, dated December 2014. This draft revision contains 

only minor changes to the regional haze sections, but further changes will be made to 

maintain alignment between this guidance document and any new EPA guidance on the RPG 

framework. EPA expects that the basic concept will be maintained that the 2028 RPG should 

be set by projecting the air quality outcome that will be produced by the measures in the long 

term strategy.

Question

1. What issues, for example the issue of the base year for modeling, should EPA address 

more specifically or differently?

o
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Pre-Meeting Materials for the EPA-FLM-RPO-States-Tribes Meeting 

on the Future of the Regional Haze Program

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Topic IV: Reasonable Progress and Long Term Strategy (Four 

Factors) 

Relevant Background 

For the next (and subsequent) regional haze planning periods, RH SIPs will focus on achieving 

additional emission reductions needed to make reasonable progress towards the goal of 

preventing and remedying impairment in visibility at Class I areas due to manmade air pollution. 

The Clean Air Act and the RHR require that four factors must be considered in determining 

whether the long term strategy in the SIP provides for reasonable progress towards this goal:

 The costs of compliance.

 The time necessary for compliance.

 The energy and non-air quality environmental impacts of compliance.

 The remaining useful life of any potentially affected sources.

The URP and RPG framework play a role in the assessment of whether a SIP provides for 

reasonable progress. Under the current RHR, the URP line (or “glidepath”) is an analytical 

framework. Adopting a 20% worst days RPG for a Class I area (corresponding to the long term 

strategy) that is on the URP line does not per se mean that a SIP provides for reasonable progress 

at that Class I area. An RPG that is above the URP line does not per se mean that a SIP does not 

provide reasonable progress. The RHR provides that if the RPG for the worst 20% of days that 

corresponds to the long term strategy is above the URP line, the state must demonstrate, based on 

the four factors, that the rate of progress that would be necessary for the implementation plan to 

attain natural conditions by 2064 is not reasonable; and that the progress goal adopted by the 

State is reasonable. The State must also provide to the public for review as part of its 

implementation plan an assessment of the number of years it would take to attain natural 

conditions if visibility improvement continues at the rate of progress selected by the State as 

reasonable.

The RHR says that the RPG for 20% best days, i.e., the projected visibility conditions at the end 

of the planning period resulting from the long term strategy, may not be higher than in the 

baseline period.

The RHR does not explicitly require a state to consider visibility impacts of individual sources 

when selecting additional controls for inclusion in its long term strategy. EPA has stated that 

states may consider such impacts, and EPA has done so in developing FIPs.

All stakeholders expressed concern with the existing EPA guidance for setting RPGs, and 

recommended that EPA more clearly articulate expectations for how to consider the reasonable 

progress four factors and visibility benefits and how to conduct a demonstration showing that 

these factors were taken into consideration in establishing RPGs.

EPA has received mixed input on the topic of the role of visibility impacts in developing the long 

term strategy. Some stakeholders recommended that visibility be made an explicit “fifth” factor. 

Some stakeholders were concerned that a possible outcome of having visibility impacts be 

considered a fifth factor could be that few additional controls would be incorporated into the 

long term strategy even though many additional control options with some visibility benefits 
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may be available, because each in isolation would have only a small effect compared to the 

visibility threshold values that were typically used for BART purposes in the first planning 

period.

Issues

A. Issue Statement – Determining cross-state impacts

These determinations are important because they affect state-to-state consultation 

requirements and the analysis of what additional emission controls are needed to make 

reasonable progress for each Class I area. In the first planning period, states used a variety of 

methods to make these determinations, some based on explicit modeling and some not.

Questions

1. Were any of the methods used in previous SIPs particularly strong or weak in terms of 

technical validity?

2. How resource intensive were these methods? Will resources be available to use these 

methods again?

3. Should EPA provide additional guidance on ways in which this can be done? What 

should it say about the analysis method? About the threshold for a contribution to create a 

linkage?

4. Should EPA approve a new SIP submission for this element if it simply carries over the 

attribution findings of the previously approved SIP regarding which Class I areas are 

affected, without new analysis? Should this only be possible if certain conditions are 

met? For example, if the state’s emissions have not increased, should EPA approve the 

SIP if it relied on the same analysis conducted for the first planning period? 

5. Should these linkages be based on most recent conditions, or on projections of state-tostate impacts in 2028 (or a convenient projection year near 2028) assuming “on the 

books” controls? 

B. Issue Statement – Linkage between the URP and the determination of whether the long 

term strategy provides reasonable progress

Questions

1. How should EPA guidance address situations where a long term strategy and 

corresponding RPG for the 20% worst days indicate that a state is on or below the URP 

line? For example, should such situations constitute reasonable progress, without further 

source-specific four factor analysis?

2. Should EPA guidance encourage states to adopt long term strategies and RPGs for the 

20% best days that provide for definite improvement on those days? How much 

improvement?

C. Issue Statement – Tiering (or screening out) sources for the four factor analysis

How can the process or criteria EPA may recommend in guidance for determining whether 

additional controls are needed for reasonable progress be structured in a common sense 
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Pre-Meeting Materials for the EPA-FLM-RPO-States-Tribes Meeting 

on the Future of the Regional Haze Program

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manner? For example, would a low-resource tiering (or screening) procedure and criteria be 

useful, with different recommendations for further analysis for sources in different tiers?

Questions

1. What procedure and criteria are appropriate?

o For example, is there a value of Q/d that would be appropriately recommended for 

this purpose? 

o Is there an alternative screening method to Q/d?

o If the screening step uses emissions, should it be based on most recent emissions 

or emissions projected to 2028?

o Can one of the four factors be used on an individual basis to screen out a source, 

or to prevent it from being screened out?

o Can visibility impacts be used to screen out a source, or to prevent it from being 

screened out?

2. Should the FLMs be able to identify to a state, at some defined early point in the SIP 

development timeline, a particular source that may not be screened out of a robust four 

factor analysis? 

D. Issue Statement – The four factor analysis

Questions

In General

1. What aspects of the BART guidelines (for each factor) are applicable to and appropriate 

for reasonable progress analyses?

2. Should EPA recommend a presumption that certain controls are needed for reasonable 

progress, for any particular source or types of source? 

Cost of Compliance

3. During the development of the first planning period SIPs, the RH program was criticized 

for requiring some sections of the Control Cost Manual to be used, even when they

contained outdated information. Should EPA plan to again recommend adherence to the 

OAQPS Control Cost Manual generally, or recommend adherence to only specific 

sections of the Cost Manual in order to limit room for misunderstanding? Should some of 

Cost Manual principles be recommended, but not via reference to the Cost Manual itself?

o For BART-eligible sources, the appropriate approach to consideration of existing 

controls, especially if installed recently, has been a source of controversy in the 

first planning period. Opinions have differed on whether and when controls that 

have been recently installed should be used as the baseline for calculating costs 

and visibility benefits of potential additional controls, versus the earlier condition 

of the source. This issue is related to considering “average costs” versus 

“marginal costs” of controls that have not yet been installed. 

o What are your views on this issue in the context of reasonable progress analysis?
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o What additional or revised guidance on these topics do you recommend EPA 

adopt for the second planning period?

4. Should state and EPA decisions to require or not require specific additional controls in 

the first planning period, that had particular costs associated with them, be used to 

establish cost benchmarks to guide to decisions on what controls are needed for 

reasonable progress in the next planning period? How?

Time Necessary for Compliance

5. Except for BART, neither the CAA nor the existing RHR set specific deadlines for when 

sources must comply with any new requirements in a state’s next Regional Haze SIP, so 

states have discretion in establishing reasonable compliance deadlines for measures in 

their SIPs. What recommendations should EPA give in new guidance on selecting a 

compliance deadline, once it has been determined that additional control of a specific 

source is needed for reasonable progress? What are the advantages and disadvantages of 

recommending the BART compliance deadline approach, which is as expeditiously as 

practicable but not more than 5 years after EPA approval of the SIP? Should EPA’s 

guidance include recommended compliance deadlines for particular controls?

Energy and Non-Air quality Environmental Impacts of Compliance

6. Should EPA recommend any particular approach to how these impacts should be taken 

into consideration? In particular, should there be any change from the BART Guidelines 

approach on this topic?

Remaining Useful Life

7. The BART Guidelines require that only enforceable source closures can be considered in 

determining the remaining useful life of a source, for example for purposes of calculating 

annualized costs. Should new EPA guidance recommend the same approach be applied 

for reasonable progress purposes, or should reliance on non-enforceable industry plans 

and forecasts be endorsed?

E. Issue Statement – Consideration of visibility impacts

Questions

1. How should visibility impacts be considered in assessing whether a source should be 

controlled under reasonable progress?

2. The BART Guidelines required that visibility impacts for BART-eligible sources be 

determined relative to natural conditions, not current conditions. This aspect of the 

Guidelines has been upheld by federal courts of appeals. Should natural conditions also 

be used for reasonable progress analysis?

3. What specific visibility metrics should EPA encourage states to consider in the next 

planning period?

4. Can a threshold or bright line for visibility impact for a source be recommended for use 

in some way, when analytical methods for determining visibility impact may vary?
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on the Future of the Regional Haze Program

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5. How should the cumulative visibility impact of many small sources on many Class I 

areas be taken into account in deciding what is necessary for reasonable progress at all

areas?

6. In the first planning period, EPA did not require but did allow states to consider 

cost/deciview metrics. Should EPA encourage the use of a cost/deciview metric, to 

inform air agency decision makers and public comment on draft SIPs for the second 

planning period? 

F. Issue Statement – Smaller point sources, area sources, and mobile sources

Question

7. Are there source categories that are of high interest to air agencies or stakeholders, for 

which EPA guidance might help facilitate dialog and reasoned decision making? What 

could EPA usefully say about these categories?