Alaska·Arizona·California·Colorado·Hawaii·Idaho·Montana·Nevada·NewMexico·NorthDakota·Oregon·SouthDakota·Utah·Washington·Wyomi ng WESTAR, 3 Caliente Road #8, Santa Fe, NM (505) 930

- 5197 WESTERN STATES AIR RESOURCES COUNCIL

May 11, 2016

U.S. Environmental Protection Agency EPA Docket Center (EPA/DC) 1200 Pennsylvania Avenue N. W. Washington, D.C. 20760

Docket ID No: EPA

- HQ

- OAR

- 2016

- 0097

RE: Western States Responses Regarding Background Ozone and Recommendations for

Additional Efforts in the Western U.S.

The Western States Air Resources (WESTAR) Council, an association of 15 western state air quality managers, app reciates the opportunity to share our input on aspects of background ozone (O 3 ) that are relevant to attaining the 2015 NAAQS. WESTAR has several recommendations to

share with EPA based on our review of the Implementation of the 2015 Primary Ozone NAAQS: Issues Associated with Background Ozone White Paper for Discussion (White Paper). In general, western states are concerned with the characterization of U.S. background (USB) O 3 and the limited CAA regulatory relief mechanisms offered through exceptional event exclusions or area designations.

WESTAR herein offers suggestions for EPA’s consideration to strengthen the assessment of

USB O 3 in the western U.S. As part of the recommendations, WESTAR offers its services in engaging states, EPA, and other stakeholders cooperatively in some of these activities. A summary of WESTAR’s recommendations is provided below. A more detailed discussion of

these recommendat ions and WESTAR’s concerns is included in WESTAR’s responses to questions posed in the White Paper, as found in the Attachment.

• EPA, in coordination with western states, should continue its efforts to characterize USB

O 3 in the West. A supplement to the White Paper that specifically addresses high USB

O 3 concentrations at high

- elevation, rural m onitors across the western U.S. that don’t respond to regional precursor reductions, would provide a better common understanding

of this situation. Guidance on ev aluating these concentrations will be beneficial to all affected states, as well as to the understanding of interstate transport of O 3 in general.

• To clarify the relationship between USB O 3 estimates and events that quality for relief through the Exceptional Events Rule, western states would benefit from a clear, explicit statement from EPA regarding the role of models and other data in determining USB O 3

.Alaska·Arizona·California·Colorado·Hawaii·Idaho·Montana·Nevada·NewMexico·NorthDakota·Oregon·SouthDakota·Utah·Washington·Wyomi ng WESTAR, 3 Caliente Road #8, Santa Fe, NM (505) 930

- 5197 • Further classification of the compo nents of USB O 3 should be addressed within the

definition of USB O 3 and modeling characterization of USB should identify the contribution of each component.

• The needs of EPA and co

- regulators for estimating USB O 3 for air quality planning purposes should b e identified in order to provide tools and timely “best available”

estimates under the CAA. Assessment and re

- assessment of USB O 3 in the western U.S. should be routine and ongoing.

• A joint EPA/co

- regulator effort should be initiated that builds on existi ng modeling expertise to refine USB O 3 estimates. Th is effort could estimate USB O 3 levels as 8

- hour averages so they are consistent with how the O 3 NAAQS is characterized and implemented.

• The influence on USB O 3 from site elevation, long

- term increases in tropospheric O 3 concentrations, stratospheric intrusion/long

- range transport events, and climatic variability (El Niño/La Niña) should be better characterized.

• Boundary conditions from global models that inform U.S. regional models used for estimating O 3 should be further evaluated. This could include:

o Identification of the criteria for determining the “best” global model for providing boundary conditions to U.S. regional models.

o Determination of the potential improvements to U.S. regional model perform ance from the “most robust” and “enhanced global model(s).” This effort could

increase confidence in modeled estimates of USB O 3

.

• EPA should provide guidance to support and inform Section 179B of the CAA so that

states understand how to create a successfu l international transport area demonstration.

• Two alternative mechanisms to address USB O 3 should be evaluated. These include: 1) assessing the principal contributor concept proposed by BP America ; and

, 2) considering a more robust natural events policy f or USB O 3

.

• In its Integrated Review Plan for a future O 3 NAAQS, EPA should include the questions raised in its White Paper, as well as those issues raised in these comments. In addition, the upcoming Clean Air Scientific Advisory Committee O 3 NAAQS Review Panel should include scientists who are actively engaged in background O 3 research and understand the policy implications of background O 3 on state implementation planning.Alaska·Arizona·California·Colorado·Hawaii·Idaho·Montana·Nevada·NewMexico·NorthDakota·Oregon·SouthDakota·Utah·Washington·Wyomi ng WESTAR, 3 Caliente Road #8, Santa Fe, NM (505) 930

- 5197 T hank you for considering WESTAR’s recommendations and our responses to the White Paper questions. We hope to continue the important conversations and working relationship with EPA

to address USB O 3 in the western U.S. We look forward to working with EPA to better

characterize USB O 3 and identify additional CAA mechanisms to address USB.

Sincerely,

Terry O’Clair , President

WESTAR Council

Attachment1 

### Attachment

WESTAR Responses to Questions Proposed by EPA in the White Paper 1

A. Has the EPA properly characterized the current best estimates of background O 3 ? Are there additional existing data analyses or modeling simulations that need to be folded into

the assessment?

No, EPA has acknowledged that background O 3 is not currently well characterized. In the White Paper

, EPA provided a national overview of USB O 3 . However, that does not imply that the conclusions apply equally to all states and monitors in U.S. Moreover, the western states are

unconvinced that USB O 3 will not prevent attainment everywhere in U.S., particularly in the

inter

- mountain western U.S. There is large variability in the influence of USB O 3 across the U.S.

EPA noted that modeled USB O 3 estimates reviewed in the Integrated Science Assess ment ( ISA ) “compare reasonably ,” post

- ISA review of modeled USB estimates “show greater variability ,” and EPA modeling is “roughly consistent with previous estimation exercises

. ” 2 In the inter

mountain w est, boundary condition contributions often exceed 5 0 percent

. 3 EPA suggests that “there may also be a limited number of rural areas where USB O 3 is appreciable

. ” 4 However, the White Paper 5 lists seven counties in the inter

- mountain western U.S. outside California with

2012

- 2014 Design Values (DV) greate r than 70 ppb and fractions of 2017 DVs from manmade U.S. sources less than or equal to 15 percent. All of these counties have fractions of 2017 DV

from manmade in

- state sources less than 10 percent and five additional counties have

contributions from in

- state sources less than or equal to 10 percent. These twelve counties with less than or equal to 10 percent contribution from in

- state sources are located across six states encompassing much of the inter

- mountain western U.S.

USB O 3 is enhanced by natu rally occurring stratospheric intrusions (SI) and long

- range transport (LRT) of international emissions, both natural and anthropogenic. The results of the Las Vegas Ozone Study 6 suggest contributions resulting from these events are much more frequent tha n EPA has acknowledged, but as EPA states, models “are not capable of precise background estimates on a daily level. ” 7 In many cases, t he high USB O 3 in the western U.S. leaves little margin for contributions resulting from manmade U.S. sources or manmade in

- state sources without exceeding the 2015 O 3 NAAQS. The potential stigma associated with having large areas

of the inter

- mountain western U.S. des ignated as nonattainment will stifle potential economic

1 U.S.	EPA, Implementation	of	the	2015	Primary	Ozone	NAAQS:	Issues	Associated	with	Background	Ozone	White
Paper	for	Discussion

, referred	to	as	White	Paper	throughout	this	document

2 Ibid.	at	4

– 5.

3 Ibid.	at	24,	T able	2c.

4 Ibid.	at	7.

5 Ibid.	at	24,	Table	2c.

6 Langford,	A.O.,	et	al,	2015. An	overview	of	the	2013	Las	Vegas	Ozone	Study	(LVOS):	Impact	of	stratospheric
intrusions	and	long

- range	transport	on	surface	air	quality .	Atmos.	Environ, http//dx.doi.org/10.1 016/atmosenv.2014.08.040.

7 White	Paper,	supra	note	1,	at	4.2 growth and present s immense interstate planning challenges towards meaningful implementation of CAA requirements.

States and locals will address the requirements of CAA § 110 in their 2015 O 3 NAAQS infrastructure state implementation plans (i

- SIPs) due October

, 2018 and attainment plans due in December, 2020. EPA modeling will be critical to better characterize USB O 3 and inform planning for these SIPs. Robust model performance evaluations and ide ntification of the strengths, as well as limitations of model performance will be of great value, especially in light of the interstate transport “good neighbor” provisions

. 8

S ince the western region is most affected by high USB O 3 in ways that are not completely understood, WESTAR suggests additional data analyses and modeling are necessary to develop a more comprehensive assessment of the role of USB. WESTAR appreciates the engagement with EPA during the recent USB Workshop 9 and requests EPA continue its efforts to address USB O 3 and transport across the western U.S., similar to EPA’s long

- standing efforts in the eastern U.S. involving the Ozone Transport Commission, NO

x SIP call, and Cross

- State Air Pollution Rule. Preparation of a white paper documenting further evaluation of USB O 3 and transport in the

inter

- mountain w est where monitors do not respond to regional reductions in O 3 precursor emissions would be a good fi rst step.

Ozone and O 3 background are at the forefront of atmospheric research activities and the level of scientific understanding is expanding at a rapid pace. For example, the journals Science of the Total Environment and Atmospheric Environment hav e recently published issues with sections dedicated to furthering the understanding of O 3 in rural United States, titled “The Nevada Rural Ozone Initiative: A Framework for Developing an Understanding of Factors Contributing to

Elevated Ozone Concentration s in Rural and Remote Environments” (October, 2015) and

"Observations and source attribution of O 3 in rural regions of the Western United States ," (May, 2015)

, respectively. NOAA conducts numerous field campaigns to investigate O 3 (e.g., CalNex,

FRAPPE / DISCOVER

- AQ, CABOTS, etcetera). A Western Regional Air Partnership (WRAP) webpage 10 provides links to presentations to Western States Air Council’s (WESTAR) Ozone Background Workgroup by experts in the field, presentations related to O 3 by WRAP technical

s taff, and O 3 - related workshops or forums hosted by others. Consideration of these and other technical resources documenting the advancements in the stat e of the science may assist EPA with further characterizing O 3 background.

In summary, WESTAR offers the time, expertise, and leveraged resources of its technical and planning committees, and working groups of topical experts, in coordination and collaboration with EPA, to support furthering the understanding of USB O 3 through the d evelopment of a

white paper regarding the role of ozone background specific to the western U.S.

8 Memorandum from Stephen D. Page to Regional Air Directors, Information on the Interstate Transport “Good Neighbor” Provisions for the 2008 Ozone National Ambient Air Quality Standards (NAAQS) under Clean Air Act (CAA) Section 110(a)(2)(D)(i)(I) , 2015.

9 U.S. EPA Workshop to Advance the Collective Understanding of Technical and Policy Issues Associated with Background Ozone, February 24

- 25, 2016, Phoenix, AZ. Referred to as Workshop throughout this document.

10 http://www.wrapair2.org/WestJumpAQMS.aspx3 B. What additional data elements and/or modeling improvements are needed to improve characterization of background O 3 levels across the U.S.?

Although EPA has used state

- of

- the

- art modeling to assess USB O 3 , large uncertainties and errors remain. Additional research and development are required to improve the models and results, as EPA acknowledged during the Workshop

. WESTAR appreciates EPA’s efforts in this area. Clearly this is a long

- term process, but the current limitations should be acknowledged.

EPA suggests monitored concentrations are not indicative of USB O 3 because of the effects of U.S. anthropogenic emissions

. 11 WESTAR notes there are two O 3 monitoring sites located on or near the coast of California and Oregon that should be appropriate to use for determining USB

O 3 resulting from long

- range transport. These two sites are Trinidad Head, C alifornia (operated by NOAA) and Mt. Bachelor, O regon (operated by the Univers ity of Washington). Data from these sites have been widely used in the past as indicators of Asian transport and could also be used for global model validation efforts. There are likely other sites along the West C oast and

the Mexican or Canadian borders that could be utilized to evaluate USB O 3 impacts.

Evaluation of the temporal variability of U.S. emissions contributions to monitored O 3 concentrations could be used as part of a weight of evidence approach that integrates observational data, including satellite and other remote sensing information, along with modeling

to assist EPA in identifying USB O 3 . It may be that for remote monitors the contributions by U.S. anthropogenic emissions to the observed O 3 may fall below the errors and biases of model

estimates of USB O 3

.

There are several areas in which EPA might conduct additional assessment s and evaluation s to
better understand the role of USB O 3 in the western U.S.

, including : global model evaluati on (i.e., boundary conditions); assessing the significance of increasing mid

- tropospheric O 3
concentra tions over the last two decades; the role of site elevation and climatic variability in

USB O 3 ; and

, development of more precise hourly and daily estimates of USB O 3

.

Boundary Conditions and Global Models

WESTAR has previously provided comments 12 suggesting the need of further evaluation

, including sensitivity testing, of the global models used to inform boundary conditions for the CONUS modeling doma in . The comments also addressed EPA’s practice o f holding boundary conditions constant when conducting CONUS modeling exercises for projected future

conditions. These comments remain germane to furthering the understanding of the role of boundary conditions in modeling USB O 3

.

WESTAR appreciates the efforts EPA has made to refine estimates of background O 3 , especially its outreach to the global modeling community. A robust review of global model performance at rural monitors across the West would inform sensitivity analyses using a number of the bes t

11 White Paper, supra note 1, at 3.

12 WESTAR letters to Chet Wayland, OAQPS, dated April 9, 2014 and June 11, 2014 regarding the 2011/2018

m odeling platforms.4 performing global models to inform boundary conditions for CONUS modeling, leading to better understanding of where CONUS modeling efforts to address USB O 3 could be improved.

The White Paper does not cite important modeling work on background in the western U.S. A large study sponsored by western states and the BLM, the West

- wide Jumpstart Air Quality Modeling Study 13 (WestJumpAQMS) conducted extensive and well

- documented modeling studies for calendar year 2008, reaching very different conclusions a s to the quantities of USB O 3 transported to rural and urban sites across the West. The WestJumpAQMS is on par with EPA national modeling platform studies and has been thoroughly evaluated on its own by western states, federal land managers, western EPA r egional offices, and other western air quality agencies.

In addition, recent work by the WRAP investigated sensitivity of CONUS models to two global

models 14 and estimated USB O 3 employing zero

- out modeling techniques

. 15 The Intermountain

West Data Wareh ouse

- Western Air Quality Study 16 will conduct additional evaluations along these lines for the new 2014 base year modeling platform in the coming summer. An evaluation of the AM3 global model is being performed through Lamont Doherty under a separate project.

The State of Colorado and Denver/Northern Front Range Regional Air Quality Council have also conducted source apportionment and sensitivity studies of USB O 3 transport for the Denver

metro O 3 nonattainment area

. 17 Finally, EPA OAQPS and western EPA regional offices have

been close ly involved in the biannual WRAP

- EPA Modeling Workshops 18 in 2011, 2013, and

2015.

It is hard to understand why results from western modeling studies and workshop were not included in EPA’s White Paper. Consideration of these resources and that of oth ers may be of assistance to the EPA in their efforts to improve CONUS model performance, particularly in the

West

. 19 Understanding global model performance will aid understanding of CONUS model performance and increase confidence in model results by all u sers.

Increasing USB Ozone Trends

EPA has noted the increase in mid

- troposphere O 3 concentrations in remote areas over the last two decades, which could result in USB O 3 increases of up to 7 ppb by 2025

. 20 Owen Cooper, NOAA, suggested during the Workshop that this trend is likely to persist for another 10 to 20 years, the result of long

- lived atmospheric processes

, in spite of any reductions in international emissions. The White Paper’s discussion of futu re O 3 levels in 2025 suggests most areas in the U.S. will have design values less than the current NAAQS of 70 ppb based on modeling

13 Available from: http://www.wrapair2.org/WestJumpAQMS.aspx

14 Available from: http://vibe.cira.colostate.edu/wiki/wiki/1043/bc

- sensitivity

- mo deling

- results

15 Available from: http://vibe.cira.colostate.edu/wiki/wiki/1020/background

- air

- quality

- modeling

- results

16 Link: http://views.cira.colostate.edu/tsdw/

17 Noted in Summary at: https://www.epa.gov/sites/production/files/2016

- 03/documents/bgo3

- high

- level

summary.pdf

18 Available from: http://www.wrapair2.org/ozone.aspx

19 See: Feb 19, 2007: Multi

- Scale Modeling of the Effects of Global Change upon Regional Air Quality

20 White Paper, supra note 1, at 8.5 projections using current boundary conditions

. 21 However, the current O 3 NAAQS is at the high

end of CASAC’s recommended ra nge, the O 3 NAAQS will be subject to another periodic review prior to 2025, and EPA’s assessment is based on holding global model boundary conditions

constant which is inconsistent with current measured trends.

Further evaluation of the role of increa sing concentration trends and the influence of projected future boundary conditions on USB O 3 will be critical for the preparation of i

- SIPs and informing O 3 nonattainment planning

, especially with the potential for a lower future O 3 NAAQS. International emission inventories have a high degree of uncertainty. An evaluation of international emissions would identify where the inventories are most uncertain, and additional sensitivity analyses would determine the significance of how changes in the internatio nal emissions influence CONUS model results. Border states are particularly concerned with proper

characterization of emissions from Canada and Mexico. Since future international emissions are extremely difficult to project, sensitivity analysis is one m ethod to bracket O 3 impacts under differing growth and economic assumptions.

Assessing Site Elevation and Climatic Conditions

Ozone concentrations in the inter

- mountain western U.S. are strongly influenced by high site elevations and high mixing heig hts that enhance O 3 concentrations through natural stratospheric

tropospheric exchange and downward mixing. EPA acknowledges natural atmospheric exchange processes can transport high

- O 3 stratospheric air into the troposphere and under certain meteorologic al conditions can displace discreet plumes of stratospheric air into the troposphere 22
(i.e., SI). Recent work in Nevada 23 documents that high elevation O 3 monitor ed values do not

show the daily variation of O 3 concentrations typically recorded by other monitors, suggesting a very limited contribution from local emissions sources. It is unclear what the role of natural atmospheric exchange processes are on high elevation monitors without the enhancements

result ing from SI and LRT events. A better understanding of these processes is important for implementation planning in the inter

- mountain western U.S.

The White Paper does not discuss the contributions of LRT of Asian pollution via the subtropical jet stre am to USB O 3 identified by researchers. Several researchers have noted the frequency

with which SI and LRT events contribute to USB O 3 at high elevation western sites. Recent

NOAA research 24 suggest s these processes are frequent contributors to USB O 3 at high elevation sites. It is critical to both EPA and states for EPA to further the understanding of these processes and quantify the resulting contributions to USB O 3

.

Lin et al 2015 25 d ocumented the variations in background O 3 resulting from climate variability. Evaluating changes in boundary conditions generated by global models for La Ni ñ a and El Ni ñ o years while holding global emissions constant would provide valuable information regarding the

21 Ibid. at 9.

22 Ibid. at 3.

23 Gustin, M.S., Fine, R., Miller, M., Jaf fe, D., Burley, J., 2015, The Nevada Rural Ozone Initiative (NVROI): Insight to understanding air pollution in complex terrain , Science of the Total Environment, 530

- 531, 455

- 470.

24 Overview of 2013 LVOS, supra note 6.

25 Lin, M. et al. Climate variability modulates western US ozone air quality in spring via deep stratospheric

intrusions. Nat. Commun, 6:7105 soi: 10.1038/ncomms8105 (2015)6 influence of climate variation s on USB O 3 at high elevation sites in the western U.S. and further inform attainment and maintenance planning.

Hourly and Daily Estimates of USB Ozone

EPA suggests that there is general consistency between zero out and source apportionment modeling app roaches and thus an increase d confidence in the model findings

. 26 Since the two approaches used the same boundary conditions and meteorology, this is not surprising and only supports the idea that the internal algorithms in the two models are performing si milarly and/or the contributions of boundary conditions are so large. However, this does not confir m the models are producing the “right” USB O 3 estimates.

The contributions to USB O 3 , which can be enhanced by specific events, have not been assessed

b y U.S EPA on an hourly or 8

- hour timeframe. EPA has only considered the values of USB O 3 on possible O 3 NAAQS exceedance days in detail via a re

- analysis of zero

- out modeling

. 27

Zero

- out modeling perturbs the complex atmospheric chemistry of O 3 formation and may not be an appropriate tool to estimate USB. The significant contributions of boundary conditions may suppress perturbations of the complex atmospheric chemistry resulting from zeroing out U.S. emissions (i.e., one possibility is that th e contributions from transported pollutants is far greater than the contributions of U.S. anthropogenic pollutants so the system remains relatively stable even in the absence of U.S. anthropogenic emissions).

The form of the 2015 O 3 standard is the annu al fourth

- highest daily maximum 8

- hour concentration averaged over three years. EPA has acknowledged the uncertainty in regional

modeled estimates of USB O 3 , the difficulties with temporal resolution experienced by the global models, and the reported seas onal average estimates of USB O 3 . If the available modeling tools are not analyzing USB O 3 consistent with the current form of the NAAQS, then EPA should either make the modeling consistent with the 8

- hour form of the standard or consider implementation o f the NAAQS on a seasonal basis. Consistency between the modeling and the

form of the standard allows for more accurate estimates of state contributions and the sources of controllable emissions. Successful planning requires that states clearly understa nd the

contributions from controllable emissions from sources they can control. Thus, the modeling should be informed by a complete year of meteorological data along with improved temporal resolution. States should not be held to implementation of the “g ood neighbor” provisions when

the contributions are based on seasonal averages with limited temporal resolution, especially given the uncertainties in the estimates of USB O 3 . In addition, the form of the O 3 NAAQS suggests modeling assessments should be m ulti

- year to account for the inter

- annual variability of the processes that influence USB O 3 , as well as the influence of transported O 3

.

In summary, WESTAR has suggested several data elements and model improvements in an effort to improve USB O 3 charac terization. WESTAR offers its assistance through its technical and planning committees, as well as working groups of topical experts, in coordination and collaboration with EPA to support further characterization of USB O 3 , as follows:

26 White Paper, supra note 1, at 5.

27 Ibid. at 4.7 • Development of consensus, well

- documented, and reproducible inputs and assumptions for key western U.S. natural uncontrollable sources, regulated anthropogenic sources, and

inter national sources; as well as addressing the se same inputs and assumption with respect to glob al modeling platforms for base year and ranges of future projections.

• Development of forecasting tools for regional and jurisdiction

- specific use in warning the public about poor air quality, for international transport, wildfire impacts, of both PM and O 3 , and stratospheric intrusions of O 3 , building on the tools used by states and other agencies.

• Continuation of the biannual series of Western Modeling Workshops as a forum to discuss comparisons of model performance and needed improvement for various models used by EPA, western U.S. air agencies, and others.

• Continuation of the development of a modeling approach based on regional consensus and refined inventories, linking the work products to planning requirement timelines for both O 3 and regional haze , while providing frequent updates to background assessment s

.

• The efforts should be guided by a consensus process involving western U.S. air agencies, EPA OAQPS and EPA Regional Office s with reports out to biannual Western Modeling Workshops.

C. EPA has focused on USB in this white paper. Are there other definitions of background
ozone that concern stakeholders?

Yes. From a pragmatic point of view, the current definition works well. The definition of USB serves the purpose of providing a consistent f ramewo rk for analyses and modeling. However, from the point of view of an agency that needs to assess what is causing violations of the NAAQS, the current definition presents several issues and is of limited utility for air quality planning. In particula r, the current estimate of USB includes all contributions except those of U.S. anthropogenic emission s . It would be helpful to states if the USB estimates distinguished the contributions of different sources. For instance, it is confusing to include wild fire and SI in USB, when these events are allowed to be excluded from the calculation of design values with appropriate demonstrations under the Exceptional Events Rule (EER). Contributions from international biogenic and geogenic emissions should also be estimated separately. Characterization of the contributions from both international anthropogenic emissions, as well as interstate transport of anthropogenic emissions would facilitate the identification of long

- range transport events which may qualify f or EER relief under certain meteorological conditions.

Model estimates of USB O 3 are not well characterized on a local scale or at temporal resolutions consistent with the form of the NAAQS. In addition, the models do not robustly address episodic SI, LR T, and large fire events

- events that may qualify under the EER. Western states would benefit from a clear, explicit statement from EPA regarding the role of models and other data in determining USB O 3 . Such a statement would clarify the relationship be tween USB O 3 estimates and events that quality for relief through the EER. This statement could provide the basis for formulation of guidance for the estimation of the contribution to USB O 3 from events falling under the umbrella of the EER that are not w ell captured by model estimates, as well as

estimation of the contribution from local emission sources to observed concentrations. Guidance of this sort would assist states and locals with implementation planning and identifying meaningful emission reduct ions that could contribute to attaining the NAAQS.8 D. Does the EPA preliminary conceptual model of O 3 attainment planning align with stakeholder perspectives on the O 3 planning process?

No, the conceptual models for O 3 attainment planning do not align with states’ needs for regulatory relief from nonattainment designations resulting from emission sources beyond their control. As noted previously, monitors in six states have contributions to DVs from in

- state
manmade sources of less than or equal to 10 percent. Western states are boxed

- in by the policy relief and conceptual models for O 3 attainment proposed in the White Paper. Preparation of exceptional event (EE) demonstrations is an onerous, resource

- intensive task that may or may not be sufficient for approval by EPA. Moreover, if a state does develop and submit an EE demonstration, there is no guarantee that EPA will review much less approve such a demonstration. The provisions under CAA § 182(h) for rural transport areas and CAA § 179B for international transport are only applicable to nonattainment areas, complete with all the consequences of such designation s . These conceptual models do not provide relief for many

inter

- mountain western states where in

- state contributions to DVs are less than 10 percent.

E. Has the EPA identified all of the CAA mechanisms available to address areas influenced by background O 3 ?

No, stakeholders and agencies are exploring other potential CAA approaches to account for USB

O 3 that might provide some degree of regulatory relief. Some of these avenues would require policy changes. This effort might be similar to previous collaborative efforts between WESTAR and EPA in the development of the 1996 Natural Events Policy. Discussion of these

mechanisms is provided under the next question (F).

WESTAR disagrees that even in areas with the highest seasonal mean background concentrations “anthropogenic sources within the U.S. are largely responsible for the 4 th highest

8

- hour MDA8 concentrations

. ” 28 Western air agencies have pursued EE demonstrations to eliminate high MDA8 values resulting from nature events to lower design values. The 2015 O 3 NAAQS became effective in December

, 2015 and agencies are just now evaluating the tradeoff between prepari ng EE demonstrations and the resulting regulatory relief, and in many cases are finding the level of effort to prepare an EE demonstration is too onerous. It is important for the

EPA to evaluate whether the EER is a realistic mechanism to address areas in fluenced by high

USB O 3 by excluding data influenced by wildfire, SI, and LRT events from regulatory

consideration

, given the frequency of events and difficulty of demonstrating their roles, especially as the O 3 NAAQS approaches USB at rural western sites and even small contributions from these events may interfere with attainment.

WESTAR notes 40 CFR Part 50.1 allows for exclusion of data affected “by human activity that is unlikely to recur at a particular location ,” including both interstate and inter national transport events of anthropogenic emissions occurring under unique meteorological conditions. The unique meteorological conditions being the “event” that qualifies for exclusion. This concept is discussed in the preamble of the recently proposed draft EER revisions 29 under section V.F.1.b

28 Ibid. at 6.

29 Treatment of Data Influenced by Exceptional Events ; Pro posed Rule. 80 FR 72840, 20 November 2016.9 and warrants more refined interpretation and evaluation as one of the regulatory relief policies identified by the White Paper. Exclusion of contributions from these types of events in the monitoring data over t he inter

- mountain West has the potential to allow areas primarily impacted by USB O 3 and interstate transport with little contribution from in

- state emissions to remain in attainment of the NAAQS.

Additional EPA EE guidance will help reduce this level o f effort and streamline the process. Agencies are concerned that EPA’s policy to not review EE demonstrations without regulatory significance may skew the historical record higher, making future demonstrations more difficult to approve. Furthermore, addi tional EE demonstration guidance should facilitate weight of evidence tools incorporating easily accessible observational data for successful demonstrations.

F. What other approaches (consistent with CAA provisions) should be considered to deal with backgro und O 3 in implementing the 2015 O 3 NAAQS?

The White Paper identified three additional mechanisms for accounting for background O 3 : 1 ) revising data handling procedures to exclude exceedances attributable to background O 3 ; 2 ) deferring designations in locations impacted by background O 3 ; and/or

, 3 ) designating area influenced by background O 3 as unclassifiable

. 30 These mechanisms were not included in the overview of policy tools due to legal or other deficiencies. A more thoughtful discussion of

these deficiencies and possible solutions from the EPA might spur identification of alternative proposals that overcome these deficiencies.

WESTAR would like to continue dialogue with EPA and investigat e other CAA mechanisms to account for background O 3 . B elow are two additional concepts or policies for further discussion, 1) principal contributor concept and , 2) natural events policy. WESTAR looks to EPA to initiate

a process to collaborate and further explore these concepts and policies

.

Stakeholders have proposed a mechanism 31 to address areas with high USB O 3 through the concept of principal contributor 32 where all background contributions, regardless of origin, are excluded by either a change in the form of the standard or via the EER from

attainment /nonattainment designation following a demonstration that background is the principal

contribu tor to monitored exceedances. This would require revisions to Appendix U of 40 C.F.R. Part 50 or as part of the revisions to the EER. This concept should be fur ther explored.

In the 1990’s WESTAR worked in conjunction with EPA to develop a natural events policy for

PM 10 (see http://www.westar.org/Docs/NEPolicy.pdf ). This effort resulted in a more black an d white policy as an alternative to excluding monitor data through EER demonstrations and allows agencies to note the occurrence of natural events and subsequently remove their influence on design values without further identification of the source of the event. WESTAR would like to

30 White Paper, supra note 1, at 12, footnote 41.

31 BP American Production Company, August 20, 2015 presentation to WESTAR Planning Committee, available

from http://www.wrapair2.org/pdf/Backgroundpresentation%2008192015.pdf and briefing paper available from http://www.wrapair2.org/pdf/High%20Ozone%20Le vels%20%207_8_15.pdf

32 Also referred to as the “total background” framework, see Comment submitted by Robert L. Stout, Jr., Vice President and Head of Regulatory Affairs, BP America, available from: https://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OAR

- 2016

- 0097

- 002710 build on its experience with the Natural Events Policy, collaborating with EPA to identify needed policy changes or options and determine the level of effort for the analysis supporting natural events policy for O 3 . Both of th ese mechanisms would assist states by preventing nonattainment designation resulting from emissions beyond their control.

G. Are sufficient technical tools, data, and EPA guidance available to make the demonstrations necessary to invoke relevant CAA provis ions?

No, EPA must continue to identify tools, methods, and data sources to inform agencies’ EE demonstration packages so states can streamline the process of developing an approvable demonstration. WESTAR appreciates EPA’s efforts regarding O 3 implementation with the release of designation guidance, release of a mapping tool, and guidance for wildfire EE.

Contributions to monitored O 3 from fires, SI, and LRT events may be excluded by demonstrations under the EER, which is one of the policy rel ief mechanisms identified by EPA. However, it’s not clear the technical tools to inform EE demonstrations for these events are commonly agreed upon or available

, 33 in spite of the recent release of draft guidance for wildfire

event demonstrations 34

.

Distin guishing contributions between SI and LRT is difficult to ascertain at the best instrumented sites and very difficult at CASTNET sites with limited instrumentation, which includes many of the impacted sites. WESTAR requests EPA devote resources to assessi ng contributions by SI and LRT to USB. It would be of great assistance to states for EPA to develop a toolbox of criteria, methods, and data resources to identify and prepare EE demonstrations for both SI and

LRT events.

The tools and data sources shou ld be publically available and of the appropriate technical sophistication to address the event. EPA staff should lead and focus efforts to identify, apply, and document the appropriate tools to meet the requirements of EE demonstrations for SI and

LRT ev ents, building on the state

- lead efforts of the Stratospheric Intrusion Workgroup coordinated by EPA Region 8. WESTAR appreciates EPA efforts to release guidance for developing demonstrations for SI EE with proposed release for external review in late sum mer 2016.

WESTAR also strongly supports development of comprehensive guidance relevant to international transport demonstrations under CAA section 179B, which is critical, based on discussions during the Workshop. These provisions appear to be one of t he primary ways under the CAA for regulatory relief and as such needs immediate attention. Approvals for the use of the 179B provisions to date have involved direct international border areas and have taken years to finalize. In contrast, the inter

- mount ain west states do not necessarily adjoin an international border, but are impacted by international emissions based on monitoring studies, source apportionment modeling, and zero

- out modeling. Another concern for western states relates to

33 WESTAR comments on U.S. EPA Exceptional Events Proposed Rule and the Draft Guidance on the Preparation of Exceptional Events Demonstrations for Wildfire Events that May Influence Ozone Concentrations . February,

2016

34 U.S. EPA, Draft Guidance on the Preparation of Exceptional Events Demonstrations for Wildfire Events that May Influence Ozone Concentrations . November 201511 the treatment o f transport of emissions from other states located upwind and how interstate transport is characterized independent of international transport. Appropriate and comprehensive guidance is needed to provide states with the information EPA will need for appro val determinations to ensure the 179B provisions can be utilized in a timely manner.

One point of particular interest is how states can leverage EPA modeling, both existing and future, to support 179B demonstrations. This would relieve the burden on states and allow agencies without photochemical modeling capability the opportunity for re gulatory relief under this CAA mechanism. It is known that international emissions vary over time and impacts change, even on a daily basis. The same can be said for emissions from states upwind of the

inter

- mountain west region. In general, states do n ot have the resources to conduct regional modeling on a daily basis to determine impacts from long

- range interstate and international transport and look to EPA to assist or provide this critical information.

In summary, EPA cannot say, without much furthe r and sustained, coordinated analysis with western air agencies, that the current understandings of background O 3 described in the White Paper are sufficient. Analyses cited in this document convey the scope, scale, and complexity of the background O 3 iss ue in the West. EPA must apply expertise and provide resources for western air agencies to be involved in developing an understanding of background O 3 for air quality analyses and planning required under the CAA. WESTAR offers the time, expertise, and

le veraged resources of its technical and planning committees, and working groups of topical experts, in coordination and collaboration with EPA, to support furthering our understanding of

USB O 3 on an ongoing basis related to above EPA questions C, D, E, F, and G.

H. Do states want or need additional assistance from the EPA to develop the demonstrations necessary to invoke relevant CAA provisions?

Yes, states look to EPA to characterize USB O 3 , not only the amounts but also the mechanisms

of the contribution of USB O 3 to observed concentrations. This characterization is a high priority for western states, preferably on a n hourly basis. WESTAR recognizes the challenges facing EPA and that the issues noted here and by others will not be resolved quickly. However, in the interim states must continue planning and implementation of the 2015 O 3 NAAQS. State programs are struggling t o meet the CAA nonattainment requirements without knowledge of whether reductions of local emissions will actually lower monitored concentrations and without having the benefit of a full understanding of the role of USB O 3 and its planning implications.

Based on recent monitoring data, (2013

- 2015, or 2014

- 2016) few areas would be designated

non

- attainment because USB O 3 is causing or will cause exceedances of the standard based on EPA projection modeling using relative response f actors to the 2025 timefr ame. However, there is a possibility that future monitoring data will record higher concentrations, just as air agencies are preparing their i

- SIPs and developing approaches to address the CAA requirements for any potential nonattainment areas. To effect ively manage implementation of the 2015 O 3 NAAQS, timely and improved analyses are needed from EPA:

• By all states to robustly evaluate interstate/inter

- jurisdictional transport that includes USB

O 3 ;12 • By states and other upwind jurisdictions contributing to nonattainment and/or interfering

with maintenance at downwind sites ; and,

• To help states and other jurisdictions manage day

- to

- day exposures at urban and rural/Class I sites to high O 3 , regardless of which source is the principal cause

– “background as def ined by models ,” wildfire, stratospheric intrusion, contributions from sources in Mexico and Canada, and even U.S. anthropogenic. Any of these days could be “Ozone Alert Days .”

WESTAR requests better tools and guidance for demonstrating EEs including lar ge wildland fires, SI, and LRT events, and especially interstate transport. The regional nature of these events suggests a regional approach spanning multiple jurisdictions and EPA regions, perhaps led by RPOs. WESTAR supports this idea and is actively e xploring this option, including identification of potential sources of funding. Regional EE demonstrations would provide consistent demonstration packages and streamline regional office approvals, a clear benefit for both states

and EPA.

EPA can play a nother important role in advancing the understanding of the role of USB O 3 in the

western U.S. Current f ederal research efforts appear to lack a coordinated effort to reach shared research goals with individual agencies pursuing important work without the benefit of a more holistic view. Such coordination might engage EPA’s f ederal partners, the f ederal land managers, as well as f ederal research partners such as NOAA and NASA. Identification of common research goals would assist coordination of research efforts, optimize funding, and fast track a better understanding of USB O 3

.

Building further on the idea of coordinated efforts, some strategically located monitors might be designated as “sentinel” monitors, providing real

- time data to inform health ad visories resulting

from O 3 events that exceed the NAAQS or alert agencies to collect additional information to inform EE demonstrations for SI or LRT events. For example, the CASTNET monitor located at Great Basin National Park might act as a sentinel for SI/LRT events while the CASTNET monitor at Rocky Mountain National Park might act as a sentinel for health

- threatening O 3 events impacting the greater Denver metro area.

Federally operated CASTNET monitors are often located far from state offices and o nly provide basic measurements. Sentinel monitors might be equipped with the more sophisticated monitoring instrumentation required to support EE demonstration packages, such as water vapor

and research

- grade CO instrumentation. Identification of sentine l monitors might be incorporated in EPA’s efforts to coordinate with its Federal research partners. EPA could also

facilitate USB O 3 research efforts by coordinating state access to lidar and other sophisticated monitoring equipment on a temporary “loaner ” basis for limited periods as agencies develop better conceptual understanding of the important sources of O 3 at its monitors.

I. What are stakeholders’ perspectives on existing programs and cooperative agreements to reduce levels of background O 3 entering the U.S.?

The White Paper only devoted one paragraph to the subject of controlling international emission sources and provided scant details of EPA’s engagement on this front or the results thereof.13 Therefore, WESTAR has not assessed existing p rograms and international agreements to reduce

O 3 entering the U.S. from international emission sources. During the Workshop, one California agency noted its engagement with international entities in its effort to curtail the impacts resulting from long

- r ange transport of anthropogenic emissions. WESTAR supports this peer

- to

- peer engagement and suggests the EPA provide all support possible to allow agencies to engage the international community and facilitate reduction of anthropogenic O 3 precursor emiss ions.

However, as noted above by Owen Cooper at the Workshop, despite reductions in international emission and due to long

- lived atmospheric processes, the trend of increasing global O 3 entering the U.S. he has documented will persist for the foreseeable future.