1. EPA’s White Paper and Workshop on Background Ozone NASA AQAST 10 th Semiannual Meeting – 1/6/16

2. Goals: EPA’s White Paper and Workshop on BGO 3 As part of an ongoing effort to work with states and stakeholders on implementation of the 2015 ozone NAAQS, EPA announced plans for a white paper and workshop on the issue of background ozone (BGO 3 ) on October 1. Goal of white paper: Establish a common understanding and foundation for additional conversations on background ozone and to inform any further action by the Agency. Goal of the upcoming workshop: Further advance collective understanding of technical and policy issues related to BGO 3.

3. EPA’s White Paper and Workshop on BGO 3 White paper online: – http://www3.epa.gov/ozonepollution/pdfs/whitepaper-bgo3-final.pdf http://www3.epa.gov/ozonepollution/pdfs/whitepaper-bgo3-final.pdf Workshop registration open online: – http://www3.epa.gov/ozonepollution/registration.html http://www3.epa.gov/ozonepollution/registration.html Workshop date/location: – Arizona Department of Environmental Quality (Phoenix) – February 24 th and 25 th

4. Outline of White Paper Overview Basics of BGO 3 : definitions, sources, & estimation techniques Summary of current estimates of BGO 3 Summary of future estimates of O 3 and BGO 3 Preliminary conceptual model of O 3 NAAQS planning Overview of policy tools Questions for further discussion (Appendix on modeling estimates) (Table combining recent design values, NOx emissions, and source apportionment modeling for counties > 70 ppb)

5. White Paper: Questions for further discussion Has the EPA properly characterized the current best estimates of BGO 3 ? – Are there additional existing data analyses or modeling simulations that need to be folded into the assessment? What additional data elements and/or model improvements are needed to improve characterization of BGO 3 levels? Does the EPA preliminary conceptual model of O 3 attainment planning align with stakeholder perspectives on the O 3 planning process?

6. White Paper: Questions for further discussion Has the EPA identified all of the CAA mechanisms available to address areas influenced by BGO 3 ? What other approaches (consistent with CAA provisions) should be considered to deal with BGO 3 in implementing the 2015 O 3 NAAQS? Are sufficient technical tools, data, and EPA guidance available to make the demonstrations necessary to invoke relevant CAA provisions?

7. Workshop Details Two day workshop: – Day 1 limited to state, local, and tribal agencies, not open to public – Day 2 intended for all stakeholders, open to public Agenda yet to be finalized (may look something like this): – Overview / key questions related to BGO 3 – Estimates of BGO 3 – Exceptional Events and BGO 3 – Nonattainment area boundaries and rural transport areas – International transport – Open discussion

8. Bottom line / Contacts Bottom line: EPA … “will evaluate the need for further guidance and/or rules to address background O3 after receiving feedback on this white paper and after conducting the workshop” Contacts: – White paper: Pat Dolwick (dolwick.pat@epa.gov) – Workshop: Yvonne Johnson (johnson.yvonnew@epa.gov):