UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION 10 

Dick Pedersen, Director 

1200 Sixth Avenue, Suite 900 

Seattle, Washington 98101-3140 

JUN 29 2012 

Oregon Department of Environmental Quality 

811 SW Sixth A venue 

Portland, Oregon 97204 

Dear Mr. Pedersen: 

OFFICE OF THE 

REGIONAL ADMINISTRATOR 

This letter responds to the Oregon Department of Environmental Quality's March 21, 2012 submittal 

regarding the 24-hour PM2.5 National Ambient Air Quality Standard exceedance at the Klamath Falls 

Peterson School site in Klamath County on September 25, 2009. The ODEQ has requested that the EPA 

concur that this exceedance was due to a wildfire exceptional event. The recorded 24-hour PM2.5 level at 

the site was 62.5 J..tg/m3

. 

Our response to the ODEQ's request is governed by the "Treatment of Data Influenced by Exceptional 

Events" rule (72 FR 13560, March 22, 2007). After careful consideration of the information provided, 

we concur with the State's exceptional events flag. The basis for our decision is set forth in the enclosed 

document. 

The ODEQ included exceptional events documentation for several other flagged exceedances in 

southern Oregon in its March 21, 2012 submittal. This letter covers the September 25, 2009 Klamath 

Falls exceedance because of its potential impact on air quality decisions for the Klamath Falls PM2.

5 

nonattainment area. Our concurrence on the September 25, 2009 Klamath Falls exceedance is not 

intended to indicate the EPA's views on concurrence or non concurrence with any other flagged 

exceedances contained in the March 21, 2012 submittal. 

Note that the EPA's decisions on exceptional event exclusions are not considered final agency action 

until they are acted upon as part of a final regulatory action, such as in an action concluding that the 

affected data may be excluded from use in a designation or determination of attainment, which is subject 

to public notice and comment. 

Thank you for your timely submittal of this exceptional event documentation and for responding to our 

comments and questions about the documentation. If you have any questions or wish to discuss this 

matter further, please contact me or have your staff contact Debra Suzuki, Manager of the State and 

Tribal Air Programs Unit in the Office of Air, Waste and Toxics at (206) 553-0985. 

Enclosure 

Dennis J. McLerran 

Regional Administrator 
cc: Andy Ginsberg 

Oregon Department of Environmental Quality 

David Collier 

Oregon Department of Environmental Quality 

Anthony Bamack 

Oregon Department of Environmental Quality 
EPA Region 10 

Review of Exceptional Event Request 

Klamath Falls, OR 

24-hour PM2.s NAAQS 

Background 

On March 22, 2007, the EPA adopted a final rule, Treatment l~{ Data Influenced by 

Exceptional Events' (Exceptional Events Rule or EER) to govern the review and handling 

of certain air quality monitoring data for which the normal planning and regulatory 

processes are not appropriate. Under the EER, the EPA may exclude data from use in 

determinations of National Ambient Air Quality Standard (NAAQS) exceedances and 

violations if a state demonstrates that an "exceptional event'' caused the exceedances. 

Before the EPA can exclude data from these regulatory determinations, the state must flag 

the data in the EPA's Air Quality System (AQS) database and, after notice and opportunity 

for public comment, submit a demonstration to justify the exclusion. After considering the 

weight of evidence provided in the demonstration, the EPA decides whether or not to 

concur with each flag. 2 

ODEQ's Request 

ODEQ requested concurrence on a flagged exceedance of the 24-hour PM2.5 

NAAQS (35 [.tg/m~) that occurred in Klamath Falls, Oregon on September 25, 2009, at the 

Klamath Falls Peterson School site (AQS site 41-035-0004 ). The recorded 24-hour PM2.5 

level at the site was 62.5 [.lg/m~. Prior to and on that day, lightning-started wildfires were 

burning in southern Oregon. 

ODEQ submitted to the EPA exceptional event documentation on March 21, 2012, for this 

and several other flagged exceedances that occurred in September 2009 at the Klamath 

Falls site and other sites in Southern Oregon. This document covers only the September 25, 

2009, Klamath Falls exceedance because of its potential impact on air quality decisions for 

the Klamath Falls PM25 nonattainment area and does not indicate the EPA's views on 

concurrence or non concurrence of the other flagged exceedances. 

The EPA's Exceptional Event Evaluation 

The EPA evaluated whether the documentation provided by ODEQ for the flagged 

exceedance of the 24-hour PM2_5 NAAQS on September 25, 2009, in Klamath Falls, 

Oregon, demonstrated that the requirements of the Exceptional Events Rule were met. 

I 72 FR 13560. 2 Note that the level or documentation may vary by the type or event and can be guided in part by the relative 

magnitude of the ohserved concentrations. To ohtain concurrence. the EPA must determine that the 

demonstration is complete and provides a reasonahle technical demonstration. 72 FR 13573 (March 22, 2007). 
The table below summarizes the requirements of the Exceptional Events Rule and describes 

how ODEQ met each requirement. All references to page numbers, tables and figures relate 

to the March 21, 2012, documentation. 

Procedural Requirements: EPA's Evaluation of li'Jagged Exceedances: 

• The data are flagged in ODEQ flagged the September 25, 2009, 24-hour PM25 

EPA's AQS database. value as a wildfire exceptional event in EPA's AQS 

40 CFR 50.14(c)(2)(i) database prior to the July 1, 20 I 0, deadline. 

and (iii) 

• The public had an ODEQ provided a 30 day public comment period on the 

opportunity to review documentation for the September 25, 2009, claimed 

and comment on exceptional event exceeedance. (See cover letter from 

demonstration Anthony Barnack emailed to EPA on September 19, 

justifying data 2011.) ODEQ received comments from one 

exclusion. 40 CFR commenter, who supported exceptional event 

50.14(c)(3)(i) and (iv) concurrence. 

• Demonstration EPA received demonstration documentation from 

justifying data ODEQ on March 21, 2012, well before the deadline of 

exclusion submitted not later than 3 years following the end of the calendar 

timely to EPA. 40 quarter in which the flagged concentration was recorded 

CFR 50.14(c)(3)(i) (in this case, September 30, 2012 ). 

Technical Criteria: 

• The event satisfies ODEQ provided FRM and continuous nephelometer 

the criteria in 40 PM2.

5 data (Table 1 on page 2 and Figure 18 on page 18) 

CFR 50.1 U) (i.e., as evidence that the event affected air quality at the 

affects air quality, is Klamath Falls Peterson School site on September 25, 

not reasonably 2009. 

controllable or 

preventable, is an ODEQ provided a news article dated September 25, 

event caused by 2009, (pages 27-28), a website link to the interagency 

human activity that Incident Information System (page 1) that attributed the 

is unlikely to recur at wildfires in southern Oregon in mid-September to a 

a particular location lightning storm on September 12 and 13, 2009, and a 

or a natural event, website link to the National Interagency Coordination 

and is determined by Center Incident Management Situation Reports that 

EPA to be an described the difficulty in containing the fires, providing 

exceptional event). evidence that the September 25, 2009, event was not 

40CFR reasonably controllable or preventable and that it was a 

2 
50.14( c )(3)(i ii )(A) natural event. 

• There is a clear ODEQ provided satellite images of smoke (page 14), 

causal connection model back trajectories (page 15), weather maps (page 

between the 16), and continuous PM25 data from the Peterson School 

exceedance and the site (page 20), to establish airflow movement from the 

claimed exceptional location of the wildfires to the air at breathing level in 

event. 40 CFR Klamath Falls and provide evidence that the wildfires 

50.14( c )(3 )(iii )(B) affected air quality at the Klamath Falls Peterson School 

site on September 25, 2009. 

ODEQ also provided a map showing the location and 

size of wildfires (pages I and 13 ), locations of other 

monitors impacted by smoke during that period (page 

I), and graphically displayed historical levels of PM2.

5 in 

the Klamath Fall area during September from 2000 to 

2008 (Figure 6 on page 8). DEQ also evaluated the 

possibility of other burning contributing to the 

exceedance and found no evidence of significant 

controlled burns or agricultural burning on September 

25, 2009, as discussed below for the "but for'' 

requirement. 

Based on the suite of evidence provided, including 

satellite images, back trajectories, maps, PM2.5 data, 

meteorological data, and no evidence of other significant 

sources of burning, we conclude that there is a clear causal 

connection between the exceedance and the September 25, 

2009,event. 

• The event is To show PM2 5 concentrations during the 2009 fire 

associated with season were in excess of normal historical fluctuations, 

measured including background, ODEQ plotted data in Figure 6 

concentrations in (page 8 of ODEQ's documentation) to show that in 

excess of normal previous Septembers from 2000-2008, 24-hour PM25 

historical levels were below 20 [!g/m3

, except for a few days in 

fluctuations September 2002, when many fires were burning in 

including Oregon. Based on the presented data indicating that past 

background. 40 CFR September background levels, in the absence of 

50.14 (c)(3)(iii)(C) unwanted wildfires, are normally below 20 [!g/m3

, 

which is well below the 24-hour PM2 5 NAAQS, we 

conclude that the exceedance concentration of 65.2 

~tg/m on September 25, 2009, is in excess of normal 

historical fluctuations including background. 

3 
• There would have 

been no excecdances 

"but for'' the event. 

40CFR 

50.14( c )(3 )(iii )(D) 

Conclusion 

To show there would have been no excccdanccs "but 

for" the event, ODEQ plotted data in Figure 6 (page 8) 

and Figure 10 (page 12) to show that in previous 

Septembers from 2000-2008 (except for a few days in 

September 2002, when many fires were burning in 

Oregon), 24-hour PM2.5 levels at the Peterson School site 

were below 20 [!g/m3

. ODEQ also investigated whether 

there were any controlled burns near Klamath Falls on 

or just before September 25, 2009, and found none of 

any significant magnitude were recorded by any of the 

agencies that track controlled burns (page 28-30). We 

have no information that agricultural burning occurred 

on or just prior to September 25, 2009 (sec email from 

ODEQ to EPA dated May 23, 2012), and given other 

evidence connecting the wildfire to the excccdance, we 

have no reason to believe that agricultural burning was a 

contributing factor. Based on information about other 

burning in the area and the presented data indicating that 

air quality levels in September, in the absence of 

unwanted wildfires, arc normally well below the 24-

hour PM2.5 NAAQS, we conclude that but for the 

wildfires at the time of the September 25, 2009, 

cxceedance, there would have been no exceedance of 

the 24-hour PM2.5 NAAQS at the Klamath Falls Peterson 

School site. 

In light of the documentation submitted by ODEQ on March 21, 2012, EPA concurs on the 

PM2.

5 level of 62.5 [!g/m3 flagged as an exceptional event for September 25, 2009. 

Accordingly, we are placing a concurrence indicator in the EPA's AQS database for 

September 25, 2009. While the information and analyses presented in ODEQ's submittal 

documents do not represent the entire suite of possible evidence for exceptional event packages, 

and additional or alternate evidence may be necessary to make an exceptional event 

determination for other wildtire or other types of events, in this particular instance the EPA 

finds that the weight of evidence is sufficient for concurrence on the tlagging of the data for the 

Klamath Falls monitor on September 25, 2012. 

Note that the EPA's decisions on exceptional event exclusions are not considered final 

agency action until they are acted upon as part of a final regulatory action, such as in an 

action concluding that the affected data may be excluded from use in a designation or 

determination of attainment, which is subject to public notice and comment. 

4