UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D .C
. 20460

Ms. Ly nn e A. Liddin g ton , Co-Chair NACAA C rite ri a P o llutant s Committee 444 Nort h Ca pito l S treet, N W Suite 307 Wash in g t o n , D.C. 20 00 I Dear Ms. Liddington: 

### DEC 2 1

**J5** OFFICE OF AIR AND RADIATION

Th ank yo u fo r youT l etter dated De ce mber 14 , 20 1 5, requestin g a 15-day extensio n of the public comment period for the proposed rule re vi s ion s titled
--Trea tment of Data Influ enced by Exc epti ona l Events ·· ( Docket No. E P A -HQ-O A R- 2013
- 0572) and th e associated draft gu idance document titled ·'Draft Guidance o n the Preparat io n of Ex c eptiona l Events Demons tratio n s for Wi ldfire E vents that May Influ ence Ozo ne Co ncentrations ' · (Docket No. EP A -H Q-OAR-20 I 5-0229). After co n s idering your request. we have decided to extend the public comment period for I 5 days. We believe that a 75-day com me nt period allows inte res t ed partie s adequate time to thoroughly re v iew and analyze th ese documents and provide meaningful comments. Th e co mme nt period w ill now close on February 3, 20 1 6. Again, thank yo u fo r yo ur l etter. If you have further qu est io n s. pl ease contact me or yo ur staff may contact Phil L o r a ng, Se nior Po li cy Advisor , in the EPA 's O ffi ce of A ir Quality Planning and Standards at 

### lo rang.ph il @ epa. gov or (919) 54 1- 5463. S in cere ly ,
Janet G. Mc Cabe Acting Assis tant Admin istrator

Inte rne t Addre ss ( URL ) • ht1p:llwww
. epa . gov Re cyc l ed/Recyclable • Printed with Vegetab le 0 11 Based Inks on too•. P os t co n sume r . Process Chlonne Free Recycled PaperUNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D.C. 20460

Mr. George S . Aburn. Jr.. Co
- Chair NACAA Cri t er

ia Pollutants Committee 444 North Capi t o l S treet , NW Suite 307 Washington , D.C. 20001 De ar Mr. Aburn: 

### DEC 2 1 _ I S OFFICE OF AIR AND RADIATION

Thank you for your letter dated December 14 , 2015 , reque s tin g a 15-day extension of the public comment period for the proposed rule revisions titled .. Treatme nt of Data Influenced by Exceptional Event s' · ( Docket No. EPA-HQ-OAR-2013-0572 ) and the a s sociated draft guidance document tit led

.. Draft Guidance on the Preparation of Exceptional Event s Demon stration s for Wildfire Events that May Influence Ozone C oncentrations " (Docket No. EPA-HQ-OAR-20 15-0229 ) . After considering your request , we have decided to extend the public comment period for 15 days. We believe that a 75-day comment period allows interested partie s adequate time to thoroughly review and analyze these documents and provide meaningful comments. The comment period will now close on February 3 , 20 1 6. Again , thank yo u for your letter. If you have further questions , p lease contact me or your staff may contact Phil Lorang , Senior Policy Advisor, in the EPA ' s Office of Air Quality Planning and Standards at 

### /orang.phil @ epa.gov or (919) 541-5463. Since r ely.

Janet G. Mc C ab e Acting A ss is tant Administrator

I n terne t Address (UR L ) • h ttp:ffwww.epa.gov RecycledfRecyclablc • Pnnt ed with Vegetable Oil Based Inks on 1 00•. Pos t co n sume r . Process Chlo rin e Free Recycled Paper