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Ground-level Ozone Pollution

Ozone NAAQS Timelines

Key Dates for Ozone NAAQS Nonattainment Areas
  1997 NAAQS 2008 NAAQS 2015 NAAQS
Emission statement rule, emission inventory, and Moderate area/OTR RACT SIPs June 2006 July 2014 August 2020*
Marginal area attainment date June 2007 July 2015

August 2021*

Attainment plans and demonstrations for initial Moderate areas​ June 2007 July 2015 August 2021
Attainment plans and demonstrations for initial Serious and above areas June 2007 July 2016 August 2022
Moderate area SIPs for 11 reclassified Marginal areas -- January 2017 --
Moderate area attainment date June 2010

July 2018

August 2024

2008 NAAQS revoked -- (TBD) --
Serious area SIPs for reclassified 2008 Moderate areas -- (TBD) --
Serious area attainment date June 2013 July 2021 August 2027
1997 NAAQS revoked April 2015 -- --
Severe area attainment date June 2019 July 2027 August 2033
Extreme area attainment date June 2024 July 2032 August 2038

* For the San Antonio Marginal nonattainment area for the 2015 ozone NAAQS, the month is September instead of August.

2015 Ozone NAAQS Implementation Rules/Guidance/Tools
Action Planned Dates:
After NAAQS Promulgation
Issue Date
Final 2015 Ozone NAAQS revision, monitoring rules, exceptional event demonstration schedule, and PSD permit grandfathering provision Upon promulgation October 1, 2015

Propose Exceptional Events Rule revision and guidance on wildfire-related ozone demonstrations​

1 month November 10, 2015

Area designations guidance (including Rural Transport Areas)​

4 months February 25, 2016

Final update to PSD permit modeling guideline (Appendix W; proposed July 2015)​

8 months December 20,  2016
Draft PSD MERPs guidance 8 months December 2, 2016
Final PSD SILs guidance 8 months April 17, 2018

Final Exceptional Events Rule revision and guidance on wildfire-related ozone demonstrations​

10 months September 16,  2016
States submit area designation recommendations 12 months October 2016

Interstate ozone transport contribution assessment provided to States​

12 months January 6, 2017
 

Propose nonattainment area rules/guidance (including area classifications, SIP due dates, nonattainment NSR provisions)​

12 months November 2, 2016

Final area designations (attainment/unclassifiable)

24 months November 6, 2017
Final classifications rule 24 months March 1, 2018
Final area designations (nonattainment) 24 months April 30, 2018
(most of U.S.)

July 17, 2018
(San Antonio)
Final SIP requirements rule 24 months November 7, 2018

Update to transportation conformity guidance​

25 months June 14, 2018