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Palma, Elizabeth

From: Palma, Elizabeth

Sent: Tuesday, December 15, 2015 12:19 PM

To: 'Nancy Kruger'

Subject: Invitation: NACAA call on exceptional events - Question regarding calculating Q/D in Draft 

Wildfire/Ozone Guidance

Nancy –

Thank you for the opportunity to participate in the NACAA conference call on Friday, December 11, 2015, and respond

to members’ clarifying questions regarding the EPA’s draft wildfire ozone guidance and proposed revisions to the

Exceptional Events Rule.  

One of the clarifying questions asked, “In the Draft Wildfire/Ozone Guidance, EPA proposes to use the Q/D metric to

determine the Tier that will be required for a demonstration.  The procedure for calculating distance (D) between a

monitor and a fire is unclear, particularly in the event of large (thousands of acres) wildfire or multi‐fire complex.  Can

you provide clarification on U.S. EPA's expectations as to how that calculation would be done?”  

Although we verbally provided the response below, we thought it would also be helpful to send our response via email

so that you can see the “math.”

We will include this email in Docket EPA‐HQ‐OAR‐2015‐0229 so that other interested parties can also see our response.

Thank you for your continued interest in the Exceptional Events process.

Regards,

Beth

Beth W. Palma

USEPA Office of Air Quality Planning and Standards

109 TW Alexander Drive (C539‐04)

Research Triangle Park, NC  27711

palma.elizabeth@epa.gov

919.541.5432

*************************************

For situations where only one fire parcel is thought to affect a monitored ozone concentration:

The distance between the latitude and longitude of the monitor and the latitude and longitude of the fire

(accounting for the curvature of the Earth should be used). The reported latitude and longitude of the fire from

inventories is generally the centroid of the fire parcel.

For situations where multiple fires are thought to contribute to a monitored ozone concentration:  

The distance (D) between the “fire” and monitor should be determined using an emissions weighted average

distance between the fire and the monitor. Two hypothetical scenarios are presented below – one for 2 fire parcels

that contribute to an ozone concentration and one for 3 contributing fire parcels.

For example, if 2 fire parcels A and B are found to contribute to an ozone concentration on a given day, find the

locations and emissions (sum of NOx and VOC) for each fire parcel. If parcel A is the closest fire, at 100 km from the

monitor and has relatively low emissions such as 1,000 tons while parcel B is further from the monitor at 200 km

and has larger emissions such as 10,000 tons, then you would calculate the emissions weighted distance as

emissions A times distance A plus emissions B times distance B. Then this weighted sum is divided by the sum of the
2

emissions A and B. Or, filling in the numbers, 100*1,000 + 200*10,000 divided by 11,000. The emissions weighted

distance would then be 190.9 km, and the Q/D would be 11,000/190.9 or 57.6 tons/km. This makes sense that the

weighted distance would be closer in magnitude to the fire with the larger emissions, but slightly smaller than the

actual distance to parcel B because there may be some contribution from the closer, smaller fire A.

For example, if an agency determines that 3 fire parcels contribute to the ozone concentration, the distance

between center of fire parcel and monitor would be:

ሻ஼ܦ஼ܦሺ ൅ ሻ஻ܳ஻ܦሺ ൅ ሻ஺ܳ஺∗ܦሺ ൌ ܽ݊ܿ݁ݐݏ݀݅	ܽ݃݁ݎ݁ݒܽ	݁݀ݐ݄݁݅݃ݓ	ݏ݊݋݅ݏݏ݁݉݅

ܳ஺ ൅ ܳ஻ ൅ ܳ஼

   

Distance between

center of fire

parcel and

monitor (km)

Sum of NOx and

VOC emissions on

day being

investigated

Weighted

distance between

the aggregate fire

and the monitor

Q/D

Fire A 100 km 10,000 tons    

Fire B 150 km 5,000 tons    

Fire C 50 km 1,000 tons    

    16,000 tons 112.5 142.2 tons/km

From: Nancy Kruger [mailto:nkruger@4cleanair.org]  

Sent: Wednesday, December 02, 2015 9:38 PM

To: Palma, Elizabeth <Palma.Elizabeth@epa.gov>

Cc: Jones, Rhea <Jones.Rhea@epa.gov>; Mathias, Scott <Mathias.Scott@epa.gov>

Subject: Invitation: NACAA call on exceptional events

Dear Beth, 

NACAA invites you and your EPA colleagues to join us on a conference call on Friday, December 11, 

2015, to respond to our members' clarifying questions on EPA's proposed exceptional events rule and 

draft wildfire guidance. The call will begin at 1:30 PM Eastern and we expect this Q&A portion to run 

about 30 minutes after which we'll continue with a NACAA-only discussion. The call-in number and 

access code are 

We will ask our members to provide questions in advance and will forward those to you on 

Wednesday, December 9. We'll start with those questions and then open it up for additional 

questions as time allows. I don't think we'll need an EPA overview of the proposal and draft 

guidance; hopefully folks have already begun digging into these documents. 

We'll take roll at the beginning of the call and I'll provide you with a list of participating NACAA state 

and local air agencies following the call. 

Please confirm your participation and also let me know if you have any questions. 

Thanks, 

-Nancy 
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_________________________________ 

Nancy Kruger 

Deputy Director 

National Association of Clean Air Agencies 

444 North Capitol Street, NW 

Suite 307 

Washington, DC 20001 

 
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Palma, Elizabeth

From: Palma, Elizabeth

Sent: Wednesday, December 16, 2015 10:31 AM

To: Palma, Elizabeth

Subject: FW: Invitation: NACAA call on exceptional events - List of Attendees (For Docket)

EPA Participants on the December 11, 2015 Call

Beth Palma, USEPA/OAQPS

Mark Evangelista, USEPA/OAQPS

Justin Spenillo, USEPA/Region 10

Michael Flagg, USEPA/Region 9

From: Nancy Kruger [mailto:nkruger@4cleanair.org]  

Sent: Wednesday, December 16, 2015 8:27 AM

To: Palma, Elizabeth <Palma.Elizabeth@epa.gov>

Subject: Re: Invitation: NACAA call on exceptional events ‐ List of Attendees

Hi Beth, 

Here's the list from roll call: 

Rhode Island 

Connecticut 

Massachusetts 

Maryland 

Pennsylvania 

West Virginia 

Alabama 

Tennessee 

Georgia 

South Carolina 

Mississippi 

Kentucky 

Wisconsin 

Minnesota 

Illinois 

Michigan 

Oklahoma 

Arkansas 

New Mexico 

Iowa 

Missouri 

Kansas 

Utah 

Wyoming 

Colorado 

Nevada 

California 
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Washington 

Idaho 

Alaska 

Knox Co., TN 

Vandenburg Co., IN 

Harris Co., TX 

Ventura, CA 

Sacramento, CA 

San Diego, CA 

Los Angeles, CA 

Washoe Co., NV 

Seattle, WA 

Yakima, WA 

Spokane, WA 

NACAA 

SESARM 

CenSARA 

WESTAR 

Thanks again, 

-Nancy 

____________________________ 

Nancy Kruger 

Deputy Director 

National Association of Clean Air Agencies 

444 North Capitol Street, NW 

Suite 307 

Washington, DC 20001