Final Determination Regarding Good Neighbor Obligations for the 2008
Ozone National Ambient Air Quality Standard
- CSAPR Close-Out -
	On December 6, 2018, the Environmental Protection Agency (EPA) finalized a determination
that the 2016 Cross State Air Pollution Rule Update (CSAPR Update) fully addresses
interstate pollution transport obligations under the 2008 National Ambient Air Quality
Standard (NAAQS) for ozone in 20 eastern states.
	The final determination relies on EPA's latest data and modeling (released in October 2017)
to assess air quality nonattainment and maintenance for the 2008 ozone NAAQS. This
analysis found that there are projected to be no remaining nonattainment or maintenance
receptors in the eastern United States by 2023.
	In accordance with this finding, EPA has determined that these 20 states do not need to
submit state implementation plans (SIPs) establishing additional control requirements
beyond the CSAPR Update to address transported ozone pollution with respect to the 2008
ozone NAAQS. Also, EPA has no obligation to establish additional control requirements for
sources in these states.
	Consistent with a court order for agency action concerning 5 of the 20 states, EPA
proposed this action on June 29, 2018, and is finalizing by December 6, 2018. The
Agency held a public hearing on August 1 in Washington, D.C., and accepted public
comments through August 31. EPA considered these comments as we developed the final
	Under the Clean Air Act, each state is required to submit to EPA a SIP that provides for the
implementation, maintenance and enforcement of each primary or secondary NAAQS. Each
state must make this new SIP submission within 3 years after EPA issues a new or revised
	A key Clean Air Act requirement for these SIPs is that they must assure that emissions in
upwind states do not contribute significantly to problems with attainment or maintenance
of the NAAQS in downwind states (known as the "good neighbor" provision). If a state does
not submit a good neighbor SIP, or if the EPA disapproves the SIP, EPA must issue a Federal
Implementation Plan (FIP).

	In 2011, EPA finalized CSAPR to address the Clean Air Act "good neighbor" provision to
reduce interstate transport for the 1997 ozone NAAQS and the 1997 and 2006 fine particle
	In October 2016, EPA finalized the CSAPR Update to address summertime transport of
ozone for the 2008 ozone NAAQS by updating the CSAPR ozone season program. The CSAPR
Update issued new and revised FIPs for 22 states in the eastern U.S.
	In the final CSAPR Update, based on information available at that time, EPA could not
conclude that the rule fully addressed good neighbor obligations for 21 of the 22 CSAPR
Update states (for Tennessee, the CSAPR Update was a full remedy). EPA has already
approved a SIP for Kentucky finding that, based on additional information and analysis, the
CSAPR Update fully addresses that state's good neighbor obligations for the 2008 ozone
	With this determination, EPA and states have no obligation to establish additional
requirements for sources in these states to further reduce transported ozone pollution with
regard to the 2008 ozone NAAQS. This applies to states currently subject to CSAPR Update
FIPs, as well as any states for which EPA has approved replacement of CSAPR Update FIPs
with CSAPR Update SIPs. In this action, EPA also finalizes minor revisions to the existing
CSAPR Update regulations.
	EPA signed a "Supplemental Transport Memo" on October 27, 2017 to help states develop,
supplement or resubmit their good neighbor SIPs for the 2008 ozone standard. The
modeling conveyed in this memo indicated that there were no monitoring sites in the CSAPR
region that were projected to have nonattainment or maintenance problems with respect to
the 2008 NAAQS in 2023.
To read or download a copy of the final rule, go to www.epa.gov/airmarkets/final-csapr-
close-out or http://www.regulations.gov (EPA's electronic public docket and comment
system). Materials for this action can be accessed using Docket ID No. EPA-HQ-OAR-
2018-0225. The final rule is also available in hardcopy at the EPA Docket Center's Public
Reading Room.
For further information about the proposed action, contact David Risley of EPA's Office
of Atmospheric Programs, Clean Air Markets Division, at (202) 343-9177 or by e-mail at