"Wood, Dana A." <Dana.Wood@bp.com>

09/04/2012 07:39 PM To Group A-AND-R-DOCKET@EPA

cc Elizabeth Palma/RTP/USEPA/US@EPA

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Subject Attention Docket ID No. EPA-HQ-OAR-2011-0887

1 attachment

BP Exceptional Events Rule Guidance 2nd Draft Comments

- 09-04-12.pd f Exceptional Guidance Comments 09-04-12.pd



### Dear EPA,

BP America (BP) appreciates the opportunity to provide written comments to the U.S. Environmental
Protection Agency (EPA) on the Draft Guidance on the Implementation of the Exceptional Events Rule (EER) (77 Fed. Reg. 39959, July 6, 2012).

BP’s detailed comments are attached. Thank you for your consideration of BP America’s comments. If

you need any further information, you can contact me, Dana Wood, at dana

. wood @ bp

. com or 281

‐ 366

‐ 3489.

Sincerely,
Dana Wood

D ana Wood , P

. E

. S enior Environmental Technical Advisor B P America Production Compan y 501 Westlake Park Blvd

. H

ouston , TX 77079-3092 P

hone: (281 ) 366-3489 Cell Phone: (713 ) 679-1815 Fax: (281 ) 366-7105 E mai l : dana

. wood @ bp

. com

# Karen St John

Senior Director Regulatory Affairs

September 4, 2012

Attention Docket ID No. EPA

– HQ

– OAR

– 2011

– 0887 U.S. E nvironmental Protection Agency
Mail Code: 6102T 1200 Pennsylvania Ave. NW Washington, DC 20460.

Subject : Comments on Draft Guidance to Implement Requirements for the Treatment of A ir Quality Monitoring Data Influenced by Exceptional Events

Dear Beth W. Palma

,

BP America (BP) appreciates the opportunity to provide written comments to the U.S. Environmental Protection Agency (EPA) on the Draft Guidance on the Implementation of the Exceptional Events
Rule (EER) (77 Fed. Reg. 39959, July 6, 2012).

BP 's comments identify and discuss the following key issues with the EER and draft guidance
document:
1. Issues with the guidance interpretation and require d data to meet the following demon stration requirement in 40 CFR 50.14(c)(3)(iv)(D): ‚There would have been no exceedance or violations but for the event”

. 2. Additional requirements that guidance is adding that are no t included in the EER or the Clean Air Act (CAA).
3. The need for getting the wildfire guidance out before the finalization of the revisions to the PM 2.5 NAAQS on December 14, 2012.
4. Clearer presentation and definition of the information required for demonstration of each of the 6 ‚tests‛ that air agencies must address when requestin g that EPA exclude event

- related concentrations from regulatory determinations

. 5. The need for a more streamlined process for submittal and approval of exceptional events demonstration packages.
6. EPA should post demonstrations that were not approved as well a s those approved.
7. The need for additional tools and protocols for identification of exceptional events.
8. Changes that are needed to the EER.

BP’s detailed comments follow this cover letter. Thank you for your consideration of BP America’s comments. If y ou need any further information, you can contact Dana Wood at dana.wood@bp.com
or 281

- 366

- 3489

.

Sincerely,



### Karen St. John Sr. Director, Regulatory Affairs BP America, Inc.
202

- 457

- 6594 (W)
202

- 351

- 1399 (cell)

# Comme nts on the Draft Guidance to

Implement Requirements for the Treatment of Air Quality Monitoring Data Influenced by Exceptional Events

Docket ID No. EPA

- HQ

- OAR

- 2011

- 0887

September 4, 2012

Prepared for:
BP America

Prepared by: Dana Wood, PE
BP

## Ta ble of Contents

1. Introduction

................................ ................................ ................................ ................................ ..... 1

2. ‚But For‛ Test

................................ ................................ ................................ ................................ . 2

3. Additional R equirements Not Included in the EER or CAA

................................ ............................. 7

4. Wildfire Guidance Needed Quickly

................................ ................................ ................................ . 9

5. Demonstration Required for Various Types o f Events

................................ ................................ .. 10

6. Approval Process for Exceptional Events

................................ ................................ ..................... 12

7. Posting Approved and Disapproved Packages

................................ ................................ .............. 14

8. Recommended Exceptional Events Tools

................................ ................................ .................... 14

9. Recommended Rule Changes

................................ ................................ ................................ ...... 15

10. Referenc es

................................ ................................ ................................ ................................ .... 171



# 1. I NTRODUCTION

On July 6, 2012, EPA published the 2nd draft of guidance to clarify key provisions to the 2007 Exceptional Events Rule (EER) promulgated under 40 CFR 50.1, 50.14, and 51.930 on May 22, 2007. These regul ations contain requirements for state demonstrations and criteria for EPA approval for the exclusion of air quality data from regulatory decisions. The EPA requires that the following 6 elements must be addressed by the states when requesting that EPA exc lude event

- related concentrations from regulatory determinations

. 1. The event affected air quality (40 CFR 50.1(j))
2. The event was not reasonably controllable or preventable (40 CFR 50.1(j))
3. The event was caused by human activity that is unlikely to recur at a particular location, or was a natural event (40 CFR 50.1(j))
4. There exists a clear causal relationship between the specific event and the monitored concentration (40 CFR 50.14(c)(3)(iv)(B))
5. The event is associated with a measured concentration in excess of normal historical fluctuations including background. (40 CFR 50.14(c)(3)(iv)(C))
6. There would have been no exceedance or violation but for the event. (40 CFR 50.14(c)(3)(iv)(D))

From the standpoint of the determining compliance with the National Ambien t Air Quality Standards (NAAQS), the EER is extremely important because it defines the requirements for monitored
exceedance s of the standard to be excluded from non

- attainment designations that are caused by events that are outside the control of the stat es and tribes including:

 Chemical spills and industrial accidents

 Structural fires

 Transported pollution

 Terrorist attacks

 Natural events including:

 Natural disasters

 Volcanic and seismic activities

 High wind events

 Wildfires and wild land fires

 Stratosphe ric ozone intrusions

As the NAAQS are established at concentration levels close to or below background concentrations

, th e EER rule will become more important because the number exceedances of the NAAQS will
increase a s a result of ‚exceptional events.‛ However, the requirements of the EER and this draft guidance pose technical and procedural problems for states, tribes , local agencies , and EPA to exclude exceptional events from the non

- attainment designation process.

EPA has made considerable improve ment from the 1 st draft by noting that natural events do not have to be infrequent, adding a formal dispute resolution process, and adding further examples.

These comments identify and discuss the following k ey i ssues with the EER and draft guidance
docum ent:
1. Issues with the guidance interpretation and required data to meet the following demonstration requirement in 40 CFR 50.14(c)(3)(iv)(D): ‚There would have been no exceedance or violations but for the event”

. 2. Additional requirements that guidance is add ing that are no t included in the EER or the Clean Air Act (CAA).2

3. The need for getting the wildfire guidance out before the finalization of the revisions to the PM 2.5 NAAQS on December 14, 2012.
4. Clearer presentation and definition of the information require d for demonstration of each of the 6 ‚tests‛ that air agencies must address when requesting that EPA exclude event

- related concentrations from regulatory determinations

. 5. The need for a more streamlined process for submittal and approval of exceptional even ts demonstration packages.
6. EPA should post demonstrations that were not approved as well as those approved.
7. The n eed for additional tools and protocols for identification of exceptional events.
8. Changes that are needed to the EER.

Based on these issu es we recommend that EPA revise the current EER to address these issues

, improve this guidance, and develop readily accessible and efficient tools and protocols for identification and exclusion of exceptional events.



# 2. “B UT 

# F OR 

# ” T EST

The most concerning require ment for exclusion as an exceptional even t is the requirement that ‚There would have been no exceedance or violation but for the event .‛ Most air pollutant
exceedance events, especially ozone, are not a result of a single source. Ozone events can include contributions from US anthropogenic emissions (both local and regional) , natural sources of both ozone and precursors, and international transport of both ozone and ozone precursors. Determining
whether or not an exceedance would have occurred ‚ but for ‛ an exceptional event is extremely difficult if not impossible, particularly with the high standard that EPA is setting in this guidance for demonstration, with no tools or protocol s for doing such a demonstration, and the limited time provided to for submi ttal of the exceptional events package.

The March 22, 2007 Preamble to the EER states that ‚ EPA recognized, in recently acting to retain PM10 as a measure of coarse particulate, that in some instances exceedances of this NAAQS ‘‘may
be caused in whole or in part, by exceptional events, including natural events such as windstorms * * *. (and that) an exceedance may be treated as an exceptional event even though anthropogenic sources such as agricultural and mining emissions contribute to the exceedance. ’ ’ (71 FR 61216; October 17, 2006).‛ T he examples of relevant evidence EPA provides for ‚demonstration that ozone exceedances would not have occurred but for the effect of a wildfire‛, are quite concerning, particularly the following for the reasons discus sed below. The required data for “but for the effect of a wildfire” is excessive and difficult to acquire. EPA should not require so much information for “but for the effect of a wildfire” test.

“Evidence that there were no known unusual emission releas es from non

- fire sources at the time of the fire event, such as from traffic due to a sports or entertainment event or source

non

- compliance.” (

See ‚Draft Exceptional Events Rule Frequently Asked Questions‛, Attachment 2 (‚Attachment 1‛, page 9 .)

There a re an infinite number of other possible sources that could contribute to ozone formation that the states would have to review and consider.

“Evidence that the plume from the fire passed over the location of the monitoring site, and mixed down to ground level. This can include satellite images, wind data including HYSPLIT trajectories, visual smoke observations, and chemical analysis of PM filters showing elements and compounds that are markers for biomass burning.” (See Attachment 1, page 9.)3 Demonstr ating that a fire plume has passed over a monitor is extremely difficult. All the methods that EPA suggested for demonstrating that a fire plume passed a monitor are insufficient as discussed below. This should not be an example of demonstration of an

oz one exceedance due to a fire.

Satellites monitoring smoke plumes typically pass over a site a maximum of one time during daylight hours and the y do not necessarily pass over all sites daily. This means that a
satellite image will only provide a short dur ation snapshot of the smoke plume, but the plume can affect large regions as a result of changes in wind direction that will not be captured by
the satellite . Furthermore, satellites can not see smoke through cloud cover , so if there is any cloud cover, th e satellite will not see the smoke plume. Also, satellites have a difficult time seeing smoke over snow covered o r other highly reflective surfaces

The use of a model such as HYSPLIT will not show that the plume from a fire has mixed down to ground level to be detected by the monitor. Further, because of the large grid size used in HYSPLIT, it will be difficult for this model to accurately simulate 3 dimensional flow in complex terrain.

Visual identification of smoke requires large diameter particulate ma t ter. In addition, the
residence time of the particulates in smoke is much shorter than the lifetime of ozone

precursors; therefore, particulates may be removed from the plume before the ozone precursors. CO is a much better tracer for fires than PM because it has a longer residence
time (2 months )

. However, if CO is used as a tracer the monitoring equipment must have suffi cient sensitivity to identify the fire plume. A standard FRM CO monitor will not work for this purpose

PM data is not collected at most of the locations where ozone data is collected. Furthermore, PM filters have specific 24 hour averaging times which m ay ‚smooth out: peak PM impacts of the fire if the fire only impacted the monitor for an hour or so. Furthermore, some of the monitors only take measurements every 3 days.

“Altered pollutant amounts, ratios, or patterns that indicate the affect of the event rather than

non

- event sources. This information could include the l evel, timing and patterns of CO and PM; PM size distribution or composition; indicators of precursor composition and “age”, such as oxygenated VOCs, radicals, sulfates, and timing and pattern of NO2 and NO; and pollutant ratios, such as CO/NOx, CO/PM10, El emental Carbon (EC)/Organic Carbon (OC), O3/NOy and O3/CO.” (See Attachment 1, page 9.)

As discussed above, most ozone monitors are not co

- located with monitors for CO or PM which will make this demonstration impossible. Furthermore, t he residence time of the particulates in smoke is much shorter than the lifetime of ozone precursors; therefore, particulates will be removed from the plume before the ozone precursors. Also, r ain will remove the particulates and still leave precursors which produce ozone. CO is a much better tracer for fires than PM because it has a longer residence time (2 months )

. EPA should consider installing CO monitors, with the appropriately low detection capabilities, along with ozone monitors to assist in the identification of e xceptional events.

“A prediction that the “normal” ozone concentration would have been below the level of the NAAQS. “Normal” ozone concentrations can be predicted using statistical methods based on previous

- day ozone and same

- day weather variables (lik e methods used for air quality advisories in some areas) or using air quality models. If either type of prediction is included in a demonstration, EPA will likely give it consideration only if the demonstration package also4 includes information on the unce rtainty of the prediction methods, i.e., information on its past success in predicting normal ozone levels. The demonstration should also explain the predictive method in terms that are understandable enough to allow informed public comment.” (See Attachm ent 1, page 9.)

And

“A prediction based on air quality/photochemical modeling of the incremental ozone concentration due to the emissions from the fire, from comparing modeling results with and without the emissions from the fire. A demonstration that in cludes such evidence should address the uncertainties in the emission estimates for the fire including the speciation of the VOC and NOx emissions, and the uncertainties due to other aspects of the modeling platform such as grid cell size, etc.” (See Atta chment 1, pages 9 and 10.)

Developing an air quality model to determine if the ozone concentration would have been below the level of the NAAQs ‚but for‛ the event takes a great deal of time, money, and resources. Models for such an evaluation will need area and time specific (paired in time and space) meteorological data, emissions data, and fire data. Furthermore, the models have to be calibrated to actual monitoring data. The effort for just developing and gathering the needed information for such a model could take over a year to do. The EPA needs to consider that the states are very limited in both the staff and funding for doing each exceptional event demonstration. Furthermore, they are limited in the amount of time they have to develop a demons tration for consideration to ‚n ot later than the lesser of, 3 years following the end of the calendar quarter in which the flagged concentration was recorded or, 12 months prior to the date that a regulatory decision must be made by EPA ‛.

Figures 1 and 2

, taken from the Four Corners Air Quality Task Force Modeling Analysis (Stoeckenius, 2009 and 2010), show modeled contributions from various sources to ozone concentrations at two locations, Navajo Lake and Mesa Verde, prepared using ozone source apportionm ent technology (OSAT ). In OSAT, precursor emissions are stratified by source category and by source region; tracers are used to tag emissions from each category

- region pair and track transport, chemical evol ution, and removal. NO X and VOC tracers are run to apportion total ozone throughout the grid to NO X a nd VOC precursor source categories and regions. Figures 1 and 2 indicate that during the spring in the intermountain West, boundary conditions dominate predicted (and presumably measured) ozone concentr ations with very little enhancement from US anthropogenic sources

. Also, during the summer , as shown in Figures 1 and 2 , boundary conditions still dominate predicted concentrations. The boundary conditions for these simulations represent monthly average concentrations at the edge of the
12 km modeling domain shown in Figure 3 , which is essentially international transport. Figures 1 and 2 show that no one source contributes solely to each ozone event. There are cases where there are spikes with higher co ntributions from a particular source than seen historically such as the spikes from fires and biogenic sources shown in Figure 2 ; however, they are still dominated by boundary conditions and have contributions from other sources as
well. Please note that this modeling exercise took approximately 2 years to perform and cost approximately $200,000 to $300,000. It could not be done for determining exceptional events as suggested in the answer to Question 6 in the 12 month timeframe provided for the

states to do such analysis.5

Figure 1 : Source Apportionment Results for 8

- Hour Average Ozone at Mesa Verde and Navajo Lake in April ( Stoeckenius, 20 10 ) Oil and Gas

12 km US

Anthropogenic 

### Boundary Conditions

- International Transport 12 km US Anthropogenic



### Boundar y Conditions

- International Transport6

Figure 2 : Source Apportionment Results for 8

- Hour Aver age Ozone at Mesa Verde and Navajo Lake in July ( Stoeckenius, 20 10 ) Oil and Gas

Elec tric Generating Units Fire 4 km Biogenic



### Boundary Conditions

- International Transport

12 km US Anthropogenic



### Boundary Conditions

- International Transport7

Figure 3 : Four Corners Interagency Air Quality Task Force Modeling Domain ( Stoeckenius, 2009) 

# 3. A DDITIONAL 

# R EQUIREMENTS 

# N OT 

# I NCLUDED IN THE 

# EER OR 

# CAA

Although EPA states that their int ention is to ‚help air agencies comply with the Exceptional Events Rule by clarifying the rule requirements‛ 1 there are some instances in the guidance document where the required demonstrations appear to go beyond the EER and the CAA. The requirements pos ed in the guidance are in essence regulation since if they are not followed the exceptional events package will not be approved. R equirements in the guidance package discussed below need further justification for why they are necessary based on the EER or should be removed from the guidance since they attempt to regulate through guidance.

At the bottom of page 3 of the ‚Draft Guidance to Implement Requirements for the Treatment of Air Quality Monitoring Data Influenced by Exceptional Events‛ under the Tr eatment of Technical Criteria for Exclusion of Data Affected by Events EPA states:

‚ Note that if an event is natural, then the second element is not considered in a
demonstration review. In the case of an event that is initiated by a natural process, su ch as a volcano or high wind dust event, the event would be considered a natural event if sources are entirely natural or contributing anthropogenic sources are reasonably controlled 10

. This concept is explained in more detail in Attachment 2, the draft H igh Winds Guidance
document.”

“10 Human activity would be considered to have played little or no direct causal role in causing the entrainment of the dust by high wind if contributing anthropogenic sources of dust are reasonably controlled, and thus the event would be considered a natural event. If anthropogenic sources contributed significantly to a measured

1 U.S. Environmental Protection Agency, ‚Responses to Significant First

- Round Comments on the Draft Guidance Documents on the Implementation of the Exceptional Events Rule‛, 6.1.1, June 2012.8 concentration (or if emissions from anthropogenic sources alone would have resulted in an exceedance or violation of the NAAQS) and these same emis sions from anthropogenic sources are affected by an event and are reasonably controllable but did not have those reasonable controls applied at the time of the event, then the event would not be considered a natural event.

. ‛

An exceptional event is define d in 40 CFR 50.1(j) as ‚ an event that affects air quality, is not reasonably controllable or preventable , is an event caused by human activity that is unlikely to recur at a particular location or a natural event, and is determined by the Administrator in accordance with 40 CFR 50.14 to be an exceptional event. It does not include stagnation of air masses or meteorological inversions, a meteorological event involving high temperatures or lack of precipitation, or air pollution relating to source noncomplia nce. ‛ Furthermore, demonstration of an exceptional event under 40 CFR 50.14 (c)(3)( iv) states:

‚ The demonstration to justify data exclusion shall provide evidence that: (A) The event satisfies the criteria set forth in 40 CFR 50.1(j); (B) There is a cl ear causal relationship between the measurement under consideration and the event that is claimed to have affected the air quality in the area; (C) The event is associated with a measured concentration in excess of normal historical fluctuations, includin g background; and (D) There would have been no exceedance or violation but for the event

.

Nowhere in the Exceptional Events Rule does it state that anthropogenic contributions must b e reasonably controlled or preventable, it only states that the event “n ot be reasonably controllable or preventable” and that “ there would have been no excedance or violation but for the event ”

. ‛ EPA defines natural event as ‚ an event in which human activity plays little or no
direct causal role. (40 CFR 50.1 (k))‛ The rul e does not define event nor state that the exceptional event be the only cause of the exceedance. This seems to be an extreme interpretation that every contributor be reasonably controlled, particularly if without the ‚event‛ there would not have been an exceedance. Emissions levels are never zero for any pollutant. There are always multiple contributors from international and interstate transport, biogenic sources, anthropogenic sources locally, mobile, etc . However, if the typical level of emissions d oes not violate the standard and adding the event causes and exceedance it should be allowed to be an exceptional event per the regulation, regardless of the other sources. As stated before, the March 22, 2007 Preamble to the
EER even stated that ‚ EPA rec ognized, in recently acting to retain PM10 as a measure of coarse particulate, that in some instances exceedances of this NAAQS ‘‘may be caused in whole or in part, by exceptional events, including natural events such as windstorms * * *. (and that) an exc eedance may be treated as an exceptional event even though anthropogenic sources such as agricultural and mining emissions contribute to the exceedance. ’ ’ (71 FR 61216; October 17, 2006).‛

Specifically, EPA through its draft guidance interprets the term ‚natural event‛ as defined in 40 CFR 50.1(k) in a manner that could not have been contemplated by the public during the 2007 rulemaking. EPA guidance rewrites the definition of ‚natural event‛ to read ‚an event in which human activity plays little or no d irect role and emissions from anthropogenic sources that contribute to the event are reasonably controlled‛. EPA must revise its regulations through proper rulemaking before it can lawfully require states to use such an interpretation of the term ‚natural event‚ when documenting exceptional events. Otherwise it would violate the Administrative Procedures Act.

On page 23 of Attachment 1

, Draft Exceptional Events Rule Frequently Asked Questions , EPA states
that:

‚ Although the language at 40 CFR §51.930 doe s not require the preparation or submittal of a mitigation plan, it does require that the air agency develop and implement processes and9 measures that could easily become the elements of a formal, written plan. The mitigation criteria focus on specific mea sures and actions to protect public health, rather than on measures that control or prevent emissions associated with a specific event. So, a mitigation plan may include measures that apply to emissions sources in general (e.g., dust suppression
or coverin g techniques for mineral processing) rather than those measures or controls that might be discussed in the “not reasonably controllable or preventable” portion of an event demonstration (e.g., controls/measures X, Y, and Z were in place on sources A, B, an d C during the time of the event). A mitigation plan may also include procedures and responsibilities for public alerts and sheltering advisories. Because having a mitigation plan in place will help air agencies meet the EER requirements at 40 CFR §50.14(c )(1)(i) related to public notification more systematically, the EPA encourages the development and submittal of a mitigation plan with the demonstration package if one has not already been adopted. ‛

Since a mitigation plan is not required under 40 CFR 51. 930, EPA should remove this recommendation from the guidance. This is adding un

- necessary work to the states. This will duplicate the regulations and efforts that the states make through rule making and the SIP process for particulate matter. Furthermor e, a mitigation plan would be quite difficult to make for the entire state since mitigation would be very area specific.



# 4. W ILDFIRE 

# G UIDANCE 

# N EEDED 

# Q UICKLY

In the PM 2.5 NAAQS Proposal published June 29, 2012, EPA is only giving states less than one year
f rom the publication of the final rule to provide documentation for 2010

- 2012 of Exceptional Events. Several wild fires have occurred between 2010 and 2012 according to NOAA’s National Climatic Data
Center State of Climate Wildfires data ( http://www.ncdc.noaa.gov/sotc/fire/ ) as shown in Table 1 due to the reduction in controlled burns which have allowed for forest to become full of brush. Figure 4 shows that the maximum number of wildfires and acres burned in the past 10 year occurred in 2006 when the number of wildfires reach ed 96,326 and 9,871,863 acres . This is a significant amount of wildfires and areas that would need to analyze PM2.5 monitoring data to determine if the annual
exceedance was due to wi ldfires.

The wildfire guidance document is needed by December 14, 2012 when the PM 2.5 NAAQS will be finalized in order to give states adequate time to create an exceptional events package for
the revised annual PM 2.5 NAAQS. The entire years’ worth of d ata would have to be reviewed on a per hour basis to see if removing it would impact the annual average according to Table Q30

- 2. Each hour measured could have an impact on the annual average. With the wildfire guidance, EPA should post additional links to tools for identifying locations of wildfires such as NOAA’s National Climatic Data Center’s State of Climate Wildfires data, the USDA Forest Service Active Fire Maps ( http://activefiremaps.fs.fed.us/ ), th e Department of the Interior Federal Fire Occurrence Website ( http://wildfire.cr.usgs.gov/firehistory/data.html ), and others.

Table 1. Number of Wildfires and Acres Burned Per Year 20 10

- 2012 YTD (NOAA)
Year Number of Wildfires Acres Burned
2010 71,839 3,422,823
2011 73,484 8,706,852
2012 YTD 37,576 4,088,3491 0 Figure 4

. US Wildfir e Activity (NOAA)



# 5. D EMONSTRATION 

# R EQUIRED FOR 

# V ARIOUS 

# T YPES OF 

# E VENTS

Item 1 of EPA’s Attachment 3, Request for Comment on the Draft Guidance Documents on the Implementation of the Exceptional Events Rule, EPA asked for ‚ comment regarding other specific,
b roadly applicable, streamlining mechanisms that the EPA could incorporate into the exceptional event implementation process. ‛ Recommending specific types of information that EPA may want to see for various types of events for demonstration of meeting each of the tests would be helpful along with examples of the demonstration as was included in Section 3 of the ‚Draft Guidance on Preparation of Demonstrations in Support of Requests to Exclude Ambient Air Quality Data Affected by High Winds under the Excepti onal Events Rule‛. The following types of events would be good to
include:

 Wildfires

 Stratospheric

- tropospheric exchange

 International Transport

 Lightning EPA should place this information in the main document as opposed to the question and answer
attach ment or in separate attachments. EPA could have a table or something that shows the elements and types of supporting information with further explanation following the table such as
shown below on Table 2.11 Table 2. Example of Demonstration Requirements Table

40 CFR Part 50 Element High Winds Wildfires Stratospheric

Tropospheric Exchange International

Transport Lightning Affects Air Quality Demonstrated using the historical fluctuations data
and clear and causal relationship data below. Demonstrated
usin g the historical fluctuations
data and clear and causal relationship data below. Demonstrated

using the historical fluctuations
data and clear and causal relationship data below. Demonstrated

using the historical fluctuations
data and clear and causal
rela tionship data below. Demonstrated

using the historical fluctuations
data and clear and causal relationship data below. Not Reasonably
controllable or preventable Control analysis of the anthropogenic sources, control analysis of the natural sources,

reaso nableness of controls, explanation emissions despite controls, back trajectories of source area, emissions inventory Caused by human activity unlikely to reoccur at a particular location or natural event High wind is a natural event, thus no necessar y

Clear causal relationship
between measurement
and event See Table 1 below

No exceedance or violation but for the

event Data analysis based on Table Q30

- 1 and Q30

- 2 Data analysis based on Table Q30

- 1 and Q30

- 2 Data analysis

based on Table Q30

- 1 and Q30

- 2 Data analysis

based on Table Q30

- 1 and Q30

- 2 Data analysis

based on Table Q30

- 1 and Q30

- 2
The event is associated
with measured concentration in excess of normal historical fluctuations, including background Statistical analysis comparison discussed below Statistical analysis comparison
discussed
below Statistical

analysis comparison
discussed
below Statistical

analysis comparison
discussed
below Statistical

analysis comparison
discussed
below

Table 1

– Use Table 4. Example Evidence and An alysis for CCR Demonstration from the ‚Draft Guidance on Preparation of Demonstrations in Support of Requests to Exclude Ambient Air Quality Data Affected by High Winds under the Exceptional Events Rule‛

Statistical Analysis Comparison:

 Comparison of conc entrations on the claimed event day with a narrower set of similar days: Similar days could include neighboring days ( e.g., a time series of two weeks) and other days with similar meteorological conditions (possibly from other years). The objective of such a comparison would be to demonstrate that the event caused higher concentrations than would be expected for given meteorological and/or local emissions conditions.

 Percentile of concentration relative to annual data. The percentile of the event

- day concen tration should be provided for the event day relative to all measurement days over the previous 3

- 5 years. To ensure statistical robustness, the EPA expects a minimum of 300 data points to be included in this calculation. The daily statistic should be appr opriate for the form of the standard being considered for data exclusion (see Question 30).

 Percentile of concentration relative to seasonal data. The percentile of the event

- day concentration should be provided for the event day relative to all measuremen t days for the season (or appropriate alternative 3

- month period) of the event over the previous 3

- 5 years. It is appropriate to use the same time horizon as used for the percentile calculated relative to annual data.

Making a simple list of information t hat the agencies should include for each type event would

stream

- line the process and reduce requests for additional data from EPA.12



# 6. A PPRO VAL 

# P ROCESS FOR 

# E XCEPTIONAL 

# E VENTS

As EPA continues to lower the NAAQS the number of exceptional events will continue to increase. Each exceedance of the NAAQS will need to be evaluated by the state to ensure the event was not caused by an exceptional event. The lower the NAAQS, the more likely an exceptional event caused
it. For instance, a s shown in Figure 5 , there were in excess of 600 cumulative days during the spring and summer of 2006 at 12 Western CASTNET rural monitoring sites or national parks when 8

- hour
ozone concentrations were above 60 ppb, which is an average of 50 days per monitoring site

. In
addition

, EPA will need to analyze and rule on the information compiled and submitted to EPA by the states. Figure 5 also indicates that the elevated concentrations occurred almost as frequently in the spring as the summer. Researchers are just beginning to unders tand spring ozone events and many of the spring events have been predominantly attributed to both natural and international emission

sources . At the present time it is not possible to definitely conclude that all of the spring ozone events identified in F igure 5 are related to an exceptional event, however, based on analysis of surface ozone monitoring data and ozone sonde data there is evidence of a strong correlation
between high

- altitude ozone (3

- 6 km) measurements and the number of days in excess of 60 , 65, or 70 ppb at Western sites (Figure 6 ). This strong correlation between elevated ozone concentrations in the upper troposphere and rural Western ozone events suggests trans

- boundary transport as a predominant cause of the high surface events and furt her suggests that classical local ozone control strategies for urban areas will not result in reduction in monitored ozone levels at Western CASTNET
sites.

Figure 5

. Cumulative number of days in the spring and summer that o zone concentrations were above 60, 65 and 70 ppb at 12 CASTNET monitoring sites in the West during 2006.

Events such as stratospheric

- tropospheric exchange (STE) ( refers to the transport of material across
the tropopause) could be considered an exceptiona l event. STE is also known as stratosphere

- to

troposphere transport (STT) or stratospheric intrusion. STE has direct implications on the distribution of atmospheric ozone, in particular, the decrease of lower stratospheric ozone and the increase of

tro pospheric ozone ‛ (Cordero et al). Langford et al examined STE along Colorado’s Front Range during the spring of 1999 (Langford, 2009) using lidar and surface measurements. ‚A deep tropopause fold brought ~215 ppbv of O 3 to within 1 km of the highest peak s in the Rocky Mountains 

### Aver age of 50 da ys/yr per site > 60 ppb! CASTNET Sites



# • Centennial, WY



# • Goth ic, CO



# • Rocky Mountain N.P., CO



# • Yellowstone N.P., WY



# • Pinedale, WY



# • Mesa Verde N.P., CO



# • Grand Canyon N.P., AZ



# • Great Basin N.P., NV



# • Canyonlands N.P., UT



# • Petrified Forest, AZ



# • Big Bend N.P., TX



# • Mount Rainier NP, WA13

on 6 May 1999. One

- minute average O 3 mixing ratios exceeding 100 ppbv were subsequently measured at a surface site in Boulder, and daily maximum 8

- hour O 3 concentrations greater or equal to the 2008 NAAQS O 3 standard of 0.075 ppmv were recorded at 3 of 9 Front Range monitoring
stations .‛ This study show s that the stratospheric contribution to surface ozone is significant and can lead to exceedances of the ozone NAAQS for a large area

.

Figure 6

. Time series plots of ozone sond e free tropospheric ozone (3

- 6 km) concentration and number of exceedance days at a proposed standard between 65 and 75 ppb for spring (top) and summer (bottom) for 10 CASTNET sites. Notice the strong correlation between fire NOx emissions

and exceedance days in summer. Figure from Jaffe (2010).

With no tools or protocols available for identifying exceptional events, it will take the states a great deal of time and work per event to develop an exceptional events package, especially since EPA’s guidance is requiring ‚ a case

- by

- case demonstration and evaluation ‛ for each event. The current regulatory framework for dealing with exceptional events is not sufficient to deal with the anticipated very large increase in the number of events that will need to be analyzed as a result of further lowering of the NAAQS

. Neither the states, tribes, nor EPA has the resources available to continue14

with such a case

- by

- case basis approach. A more streamlined and automated approach must be developed to ensure that both t he states and EPA can efficiently evaluate exceptional events.

Furthermore, a s noted in the comments by the various states for the first draft of the guidance, EPA is behind on reviewing the exceptional events packages

. EPA has approved very few except ional events packages. EPA even stated in the First External Review Draft of the Health Risk and Exposure Assessment for Ozone (Updated August 2012) that ‚However, concurred exceptional events were rare, accounting for less than 0.01% of the total observa tions. All concurred exceptional
events in 2006

- 2010 were related to wildfires in California in 2008. There were no concurrences of exceptional event data for stratospheric intrusions in 2006

- 2010 in the data extracted on June 27,
2011. ‛

EPA must develo p a more streamlined process for the information to be submitted by the states and the approval process. Otherwise, many areas will be nonattainment for the NAAQS due to exceptional events and unable to come into compliance

.



# 7. P OST ING 

# A PPROVED AND 

# D ISAPP ROVED 

# P ACKAGES

It is helpful to the states that EPA is posting some of the approved package. If approved by the states, posting all the approved packages would assist in ensuring consistency across the regions and providing examples of the needed informat ion. EPA should also post packages that were not approved and why to help sta tes know what is not acceptable.



# 8. R ECOMMENDED 

# E XCEPTIONAL 

# E VENTS 

# T OOLS

More technical tools need to be developed and provided for states, tribes, and location agencies to help id entify exceptional events. As discussed already, as the NAAQS Standards are lowered, more and more exceedances of the NAAQS will require evaluation to determine if exceptional events
caused the exceedance. Exceedance s of the ozone NAAQS may be caused by stratospheric

tropospheric exchange ( STE ) , lightning, wildfires, or long

- range transport of international emissions and combinations of these uncontrollable sources

. Limited tools are available for identifying such events as shown on the EPA Exceptional Events Rule webpage and may not work. There are s ome tools that EPA has identified for wildfires, but identification for STE

, lightning, and international transport or combinations of these things have not been developed or identified.

STE and international transport events are the hardest to identify and the tools are currently not

a vailable for identification. Global C hemical T ransport M odels (CTMs) cannot accurately simulate the highest ozone events, which are the target of the NAAQS standard. Monitoring data can not be used if multiple trace gas measurements are not simul taneously recorded at each site since it is difficult to determine without them the source of the ozone

. Satellite remote sensing of trace gases is an appealing avenue for application to screening events. Based on currently released NASA, European and Japanese pr oducts, the most reliable measurements in the troposphere are NO 2 , CO, and HCHO. Monitoring tropospheric ozone from space has proved difficult due to the blanket of ozone in
the stratosphere, making retrievals highly uncertain. The tropospheric emission spectrometer (TES) is specifically designed for measuring ozone in the troposphere, but the signal to noise ratio makes it primarily useful for ozone in a monthly mean sense. Comparisons of TES retrievals in the troposphere with free tropospheric air at Mt . Bachelor, WA showed no significant correlation between observations and TES data (Wigder and Jaffe, 2011). The Ozone Monitoring Instrument (OMI) has the advantage of better spatial and temporal coverage, but again, no significant correlation between fre e tropospheric air at Mt. Bachelor and OMI were observed (Wigder and Jaffe, 2011). Additionally, all of the United States space

- borne ozone monitors are operating beyond their design lifetime, and15

no immediate replacements are scheduled for launch. Clear ly, in the context of the 2013 ozone standard, satellite retrievals of ozone will not provide a reliable resource for ozone sources in the troposphere.

According to Murray et. al. 2012 (in press), ‚ Nitrogen oxides (NOx ≡ NO + NO2) produced by lightning

m ake a major contribution to the global production of tropospheric ozone and OH.‛ ‚The resulting global lightning NOx source in GEOS

- Chem is 6.0 ± 0.5 Tg N a

- 1, compared to 5.5 ± 0.8 Tg N a

- 1 for the biomass burning source.‛ Fang et. al. 2010 states that ‚ Lightning is a major natural source of NOx in the free troposphere, but its magnitude is poorly constrained with a best estimate of 5 Tg N
yr

− 1 and an uncertainty range of 1

– 20 Tg N yr

− 1 [Schumann and Huntrieser, 2007, and references therein].‛ I dentifying and quantifying emissions from lightning is challenging. EPA states in the Third External Review Draft of the Integrated Science Assessmen t for Ozone and Related Photochemical Oxidants on page 3

- 62 that ‚While progress is being made in obtaining day specific data for lightning strikes and area burned in wildfires, the emission factors for precursors from these episodic sources such as lightn ing and wildfires are still uncertain.‛ Specific data can be obtained on locations of lightning strikes from sources such as NASA’s U.S. National Lightning Detection Network Database (NLDN) ( http: //gcmd.nasa.gov/records/GCMD_NLDN.html ) and other such sources; however, estimating the contribution is difficult. Fang et al 2010 states that ‚ For example, by simulating several midlatitude and subtropical thunderstorms during four field projects, Ott e t al. [2007, 2010] recommend a mean NOx production of approximately 500 moles per flash for both intracloud and cloud

‐ to

‐ ground flashes. Ott et al. [2010], Kaynak et al. [2008], and Pickering et al. [2006] suggest that a larger percentage of the total lightning NOx source is located in the free troposphere (FT) than proposed in an earlier work [Pickering et al., 1998]. ‛ The concentration increase has not been estimated. Further work is needed to help states, tribes and local agencies identify and estimate the impact from lightning. 

# 9. R ECOMMENDED 

# R ULE 

# C HANGES

As requested by many of the states, BP al so request s that the Exceptional Events Rule needs to be revised. EPA even stated in their presentation the Exceptional Events Implementation Guidance Notice of Availability on July 31, 2012 that implementing the rule is challenging including that:

 ‚EER is relatively young

 E xceptional events are unique and varied

 Difficult to provide guidance that is both concrete and generally applicable

 Difficult to pre

- determine how much evidence/technical analysis for demonstrations is enough

 Final rule text and preamble left room for int erpretation‛ The Exceptional Events Rule could be revised to address these issues through a rule proposal and comment period. BP recommends that the following changes are needed to the Exceptional Events Rule based on the comments on the first draft and the current draft guidance.

Clarity or revision to the wording is needed for the criteria that ‚There would have been no exceedance or violation but for the event‛ to clarify that the event does not have to be the only source of the pollutant. As discu ssed in Section 4, m ost air pollutant exceedance events, especially

ozone, are not a result of a single source. EPA is setting in this guidance document an extremely high standard for the ‚but for‛ test beyond the intent of the rule as discussed in the Ma rch 22, 2007
Preamble to the EER which states that ‚ EPA recognized, in recently acting to retain PM10 as a measure of coarse particulate, that in some instances exceedances of this NAAQS ‘‘may be caused in whole or in part, by exceptional events, including natural events such as windstorms * * *. (and that) an exceedance may be treated as an exceptional event even though anthropogenic sources such as agricultural and mining emissions contribute to the exceedance. ’ ’ (71 FR 61216; October 17, 2006).‛ Perhaps the wording should be changed to state that ‚the exceedance was caused in whole or in part because of the exceptional event.‛16

EPA should revise the Exceptional Events Rule to allow for the exclusion of ozone exceedances resulting for Policy Relevant Back ground or US Background based the answer to Question 16a of Attachment 1, Draft Exceptional Events Rule Frequently Asked Questions since EPA is claiming background ozone can be addressed in the implementation phase of the standard. The response to Questio n 16a makes it clear that not all background ozone can be excluded as an exceptional event. Background ozone is ozone that cannot be controlled by the states, tribes, or local agencies. Therefore, it should be excludable under the Exceptional Events Rule from the attainment demonstration process

. EPA states: ‚16a. Question: Are policy relevant background ozone concentrations and exceptional events
related? Answer: Policy relevant background ozone concentrations and exceptional events can include partiall y overlapping concepts. The 2007 Staff Paper defines policy relevant background ozone ‚as the distribution of [ozone] concentrations that would be observed in the U.S. in the absence of anthropogenic (man

- made) emissions of precursor emissions (e.g., VOC, NOx, and CO) in the U.S., Canada, and Mexico.‛ An exceptional event is a natural event (excluding stagnations, inversions, high temperatures, or precipitation) or an anthropogenic event that is unlikely to recur in the same location. Both exceptional event s and policy relevant background include emissions from natural events like forest wildfires or stratospheric ozone intrusions. However, exceedances due to natural emissions that occur every day and contribute to policy relevant background, such as biogeni c emissions, do not meet the definition of an exceptional event and are thus not eligible for exclusion under the EER. Routine anthropogenic emissions outside of the U.S. contribute to policy relevant background, but are not exceptional events. Air agency preparation of a demonstration package and the EPA’s subsequent review of the demonstration package is case

- by

- case based on a weight

- of

- evidence approach and does not explicitly consider whether the event type might contribute to policy relevant backgroun d. However, if a natural event that contributes to policy relevant background causes an observed concentration that meets the statutory definition of an exceptional event and fulfills all of the exceptional event criteria, the
EPA would consider the event to be an exceptional event.‛

The exceptional events regulation specifically precludes the exclusion of ‘routine’ exceedances caused by natural sources and ozone transport from international sources. However, the Clean Air Act (CAA) does not preclude ex clusion of ‘routine’ exceedances. The CAA defines an exceptional event under 319 (b) ( 42 USC § 7619 (b)).

‚ (1) Definition of exceptional event
In this section: (A) In general The term ‚exceptional event‛ means an event that

— (i) affects air quality; (ii) is not reasonably controllable or preventable; (iii) is an event caused by human activity that is unlikely to recur at a particular location or a natural event; and (iv) is determined by the Administrator through the process established in the regulations promulgate d under paragraph (2) to be an exceptional event. (B) Exclusions In this subsection, the term ‚exceptional event‛ does not include

— (i) stagnation of air masses or meteorological inversions; (ii) a meteorological event involving high temperatures or lack of precipi tation; or (iii) air pollution re lating to source noncompliance.‛ Therefore, the CAA leaves room for revising the Exceptional Events Rule for allowing routine
events to be excluded.17

Also, Perhaps the rule could include clearer criteria for specific types of events to be declared an exceptional event. The types of events the rule might address include wildfires, high winds, stratospheric

- tropospheric exchange, lightning, etc. Perhaps specific tests versus the generic tests could be put in place for various t ypes of events.



# 10. R EFERENCES

Cordero, Eugene, Newman, Paul A., Weaver, Clark, and Fleming, Eric, Stratospheric Ozone, electronic textbook, Chapter 6, Section 5, http://www.ccpo.odu.edu/SEES/ozone/oz_class.htm

Fang, Y; Fiore, AM; Horowitz, LW; Levy II, H; Hu, Y; Russell, AG. (2010). Sensitivity of the NOy budget over the United States to anthropogenic and lightning NOx in summer. J Geophys Res 115:
D18312. http://dx.doi.org/10.1029/2010JD014079

Langfo rd, A. O., K. C. Aikin, C. S. Eubank, and E. J. Williams (2009), Stratospheric contribution to high surface ozone in Colorado during springtime

, Geophys. Res. Lett.

, 36 , L12801, doi:10.1029/2009GL038367.

Murray, L.T., D.J. Jacob, J.A. Logan, R.C. Hudman, and W.J. Koshak, Optimized regional and interannual variability of lightning in a global chemical transport model constrained by LIS/OTD satellite data

, J. Geophys. Res. , in press, 2012. [ PDF ]

Stoeckenius, T.E., C.A. Emery, T.P. Shah, J.R. Johnson, L.K. Parker and A.K. Pollack, 2009 and 2010. Air Quality Modeling Study For the Four Corners Region and Addendum. ENVIRON International Corp., Revised Report, August 2009 and Ja nuary 2010. (http://www.nmenv.state.nm.us/aqb/4C/Modeling.html)

Widger, N, D.A. Jaffe, M. Lin, A. Fiore, A.M. Macdonald, and S. Gong. Interannual Variation in Baseline Ozone on the Western Coast of North America and Its Influence on Urban Air Quality. Presented at AGU Fall Meeting, December 9, 2011.