exceptional events process and to aid all agencies in resource planning
and prioritization, the EPA proposed that air agencies and the EPA
engage in regular communications to identify those data that have been
potentially influenced by an exceptional event, to determine whether
the identified data affect a regulatory determination, and to discuss
whether an air agency should develop and submit an exceptional events
demonstration. The proposal indicated that most of these discussions
would be between individual air agencies and the reviewing EPA Regional
office, but some discussions could involve a group discussion between
the EPA Regional office and all air agencies in the region followed by
individual discussions, as needed. In still other cases, such as where
large events cross state lines and when two or more states are pursuing
exclusion for the same event(s), the EPA region or regions may initiate
discussions with all potentially affected states/agencies to assist in
coordinating states affected by regional events.
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    \95\ Between September 2014 and March 2015 the EPA held
conference calls with some air agencies to ask about exceptional
events implementation concerns and to better understand currently
employed exceptional events implementation processes and practices.
As a result of these discussions, the EPA developed a list of best
practices for communication and collaboration between the EPA and
air agencies, a summary of which is available at http://www2.epa.gov/air-quality-analysis/treatment-data-influenced-exceptional-events.
---------------------------------------------------------------------------

    The EPA referred to these communications as the ``Initial

Notification of Potential Exceptional Event'' (Initial Notification)
process and described the purpose of the Initial Notification process
as initiating conversations between an air agency and the EPA if not
already on-going, or engaging in more detailed discussions if a process
is currently in place, regarding specific data and whether the
identified data are ripe for submittal as exceptional events. As
stakeholders have repeatedly expressed and as the EPA acknowledges, the
identification of data affected by exceptional events and the
subsequent preparation, submittal and review of demonstrations is a
resource intensive process both for the preparing air agency and the
reviewing EPA Regional office.
    The proposal also noted that if these data do not have regulatory
significance, then engaging in the development and review of an
exceptional events demonstration is generally not an efficient use of
an air agency's or the EPA's limited resources. As described in the
proposal, the Initial Notification process would focus efforts on the
relevant data and provide the EPA with the opportunity to convey to the
affected air agency our initial thoughts regarding the identified event
and analyses that may or may not be appropriate for inclusion in a
demonstration, and, with respect to regulatory significance, which
demonstrations the EPA will consider for review.
    The proposal indicated that the Initial Notification could include
any form of communication (e.g., letter, email, in-person meeting with
an attendees list and discussion summary or phone conversation with
follow-up email) that ultimately identifies the potential need to
develop an exceptional events demonstration and communicates key
information related to the data identified for potential exclusion.
Where an air agency independently identifies event-affected data and
the need to submit an exceptional events demonstration outside of its
regular, on-going communications with the EPA Regional office, the air
agency could prepare a letter or email communicating its Initial
Notification. Generally, the EPA anticipates that air agencies would
develop and provide an Initial Notification as soon as the agency
identifies event-influenced data that potentially influence a
regulatory decision or when an agency wants the EPA's input on whether
or not to prepare a demonstration.\96\ The EPA further proposed that
each Initial Notification would include the following components:
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    \96\ The EPA recognizes that air agencies can immediately
identify those events that result in an exceedance of a NAAQS with a
short averaging time (e.g., 1-hour, 8-hour or 24-hour standards) but
may need additional time for an annual average standard. An air
agency could also submit an annual Initial Notification if annual
submittal makes sense for resource planning or for recurring
seasonal events.
---------------------------------------------------------------------------

     Unique event name (field in AQS)--facilitates future
communication and understanding between the submitting air agency and
the reviewing EPA Regional office, particularly if an air agency has
submitted multiple exceptional events demonstrations.
     Initial event description (field in AQS)--provides a brief
narrative of the event that could also include maps or graphs similar
to what an air agency might include in the narrative conceptual model
discussed in Section IV.G.6 of this preamble; the event description
would include a qualitative description of the event and, at a minimum,
briefly describe the air agency's current understanding of interaction
of emissions with the event, transport and meteorology (e.g., wind
patterns such as strength, convergence, subsidence, recirculation) and
pollutant formation in the area.
     Affected regulatory decision--provides a description of
the regulatory action or actions potentially affected by the claimed
event-influenced data and the anticipated timing of this action.
     Proposed target date for demonstration submittal--
identifies the proposed target date by which the air agency would
submit a demonstration to the reviewing EPA Regional office.
     Most recent design value including and excluding the
event-affected data--the air agency's assessment of the most recent
design value both with and without the identified event(s) is helpful
when assessing regulatory significance. The EPA cannot accurately
calculate this value (and therefore may not be able to determine
significance) if the air agency has flagged more data than it intends
to include in an exceptional events demonstration.
     Information specific to each monitored day--see Table 5
for an example of the type of table that could be used, which would be
developed by the submitting air agency and generated from the initial
event description in AQS (see discussion in Section IV.G.4 of this
preamble).
[GRAPHIC] [TIFF OMITTED] TR03OC16.001

    The proposal indicated that, after one or more informal phone
discussions with the air agency, the EPA would acknowledge an air
agency's Initial Notification and then formally respond within 90 days
of receipt of the Initial Notification via letter, email or in-person
meeting with an attendees list and discussion summary. The response
would provide the EPA Regional office's best assessment of the priority
\97\ that can be given to the submission once received, any case-
specific advice the EPA may have to offer for the preparation of the
demonstration, and the target date for demonstration submittal. Where
the data are to be used in initial area designations, the EPA

proposed to rely on the documentation submission schedule that, at the
time of the proposal, appeared as Table 1 at 40 CFR
50.14(c)(2)(vi).\98\ Where the data would influence another near-term
regulatory decision, the EPA proposed to rely on the case-by-case
timelines by which the air agency should submit the demonstration. For
case-by-case demonstrations, the EPA's recommended date for
demonstration submittal would consider the nature of the event and the
anticipated timing of the regulatory decision, and would allow time for
both an air agency's preparation of the demonstration and the EPA's
review. Additionally, the EPA would request in its response that, if
the submitting air agency has not already identified the affected data
within AQS, that it undertake this effort according to the process
described in Section IV.G.4 of this preamble. If the data identified in
the Initial Notification do not have regulatory significance as
discussed in Section IV.B of this preamble, then the EPA would indicate
this in its correspondence back to the air agency and would discourage
the air agency from devoting resources to developing a demonstration
because the EPA would likely not review or act upon the submittal.
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    \97\ ``Priority'' refers to those exceptional events
determinations that affect near-term regulatory decisions.
``Regulatory decisions'' include findings as to whether the area has
met the applicable NAAQS, classification determinations, attainment
demonstrations (including clean data findings), attainment date
extensions, findings of SIP inadequacy and other actions on a case-
by-case basis determined to have regulatory significance. See
discussion in Section IV.B of this preamble for additional detail.
    \98\ This table appears as Table 2 at 40 CFR 50.14(c)(2)(vi) in
the Exceptional Events Rule revisions that we are promulgating in
this action.
---------------------------------------------------------------------------

    The proposal further noted that if the EPA has acknowledged as part
of the Initial Notification process that identified data have
regulatory significance (or some other compelling reason for excluding
data), then the air agency should proceed with the development of a
technical demonstration that satisfies the requirements in 40 CFR 50.14
and accounts for any case-specific advice from the EPA and additional
information in the EPA's guidance documents.\99\ The proposal specified
that although air agencies could submit demonstrations for events that
do not affect a regulatory action, the EPA would likely not review or
act on such submittals.
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    \99\ Interim Guidance to Implement Requirements for the
Treatment of Air Quality Monitoring Data Influenced by Exceptional
Events. Memorandum from Stephen D. Page, U.S. EPA Office of Air
Quality Planning and Standards, to Regional Air Directors, Regions
I-X. May 10, 2013. Available at http://www2.epa.gov/sites/production/files/2015-05/documents/exceptevents_guidememo_130510.pdf.
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    To support the previously summarized process, the EPA proposed to
revise the language in 40 CFR 50.14(c)(2)(i) as follows: ``A State
shall notify the [EPA] of its intent to request exclusion of one or
more measured exceedances of an applicable national ambient air quality
standard as being due to an exceptional event by creating an initial
event description and flagging the associated data that have been
submitted to the AQS database and by engaging in the Initial
Notification of Potential Exceptional Event process . . . .'' The EPA
solicited comment on the proposed rule text revision (in 40 CFR
50.14(c)(2)) to require an Initial Notification of Potential
Exceptional Event, with a provision that the EPA could waive the
Initial Notification requirement on a case-by-case basis. We also
solicited comment on making the Initial Notification of Potential
Exceptional Event a voluntary process.
    The proposal also included the associated revisions to rule text at
(ii): ``The data shall not be excluded from determinations with respect
to exceedances or violations of the national ambient air quality
standards unless and until, following the State's submittal of its
demonstration pursuant to paragraph (c)(3) of this section and the
Administrator's review, the Administrator notifies the State of its
concurrence by placing a concurrence flag in the appropriate field for
the data record in the AQS database.''
b. Final Rule
    In response to our solicitation for comment, several commenters
indicated their desire for a voluntary Initial Notification of
Exceptional Event process, while others indicated their desire that the
Initial Notification process be promulgated in rule text as a
requirement. To provide more regulatory certainty for all involved
parties, we are finalizing the Initial Notification process as
proposed, which includes a requirement for air agencies to engage in
communications with the EPA once they identify a potential event; for
air agencies to flag data within AQS, if appropriate; for the EPA to
identify a demonstration submittal date that considers the nature of
the event and the anticipated timing of the regulatory decision that
may be affected by the exclusion of the flagged data; and an option for
the appropriate EPA official to waive the Initial Notification
process.\100\ We also intend to formally respond (via email or letter)
to an air agency's Initial Notification within 60 days of receipt of
the Initial Notification.\101\ We discuss the EPA's response timeframes
in more detail in Section IV.G.7 of this preamble.
---------------------------------------------------------------------------

    \100\ As discussed in Section IV.A.2 of this preamble, if an air
agency authorizes an FLM or other federal agency to prepare and
submit exceptional events demonstrations directly to the EPA, the
air agency should also indicate in this authorization whether an FLM
can initiate the Initial Notification of Potential Exceptional Event
process and whether this process would include or exclude the
authorizing air agency.
    \101\ As previously indicated, the Initial Notification could
include any form of communication (e.g., letter, email, in-person
meeting with an attendees list and discussion summary or phone
conversation with follow-up email) that ultimately identifies the
potential need to develop an exceptional events demonstration and
communicates key information related to the data identified for
potential exclusion. The EPA's timeline for formally responding to
an agency's Initial Notification is based on the date of receipt of
the identified communication.
---------------------------------------------------------------------------

    When the EPA promulgated the revised ozone NAAQS in 2015,\102\ we
revised the flagging, initial event description and demonstration
submittal deadlines for data influenced by exceptional events for use
in the initial area designations process. We did not propose any
changes to this schedule as part of the proposed revisions to the
Exceptional Events Rule. However, because we are finalizing the Initial
Notification process in this action, which includes a requirement for
air agencies to flag data within AQS, if appropriate, and characterize
the identified event, we are revising the ``flagging and initial event
description'' language in Table 2 to 40 CFR 50.14 that we promulgated
with the ozone NAAQS to read ``Initial Notification.'' We are not
changing the schedules for event-influenced data that may affect
decisions associated with the initial area designations process.
---------------------------------------------------------------------------

    \102\ 80 FR 65292 (October 26, 2015).
---------------------------------------------------------------------------

c. Comments and Responses
    Other than the comments related to the ``voluntary'' versus
``required'' nature of the Initial Notification process, the majority
of the remaining comments on this topic pertained to the content of the
Initial Notification and to the mechanics of communications between the
EPA and affected air agencies. Two state commenters agreed with the
proposed content of the Initial Notification to include: A unique event
name, an initial event description, the affected regulatory decision, a
proposed target date for demonstration submittal, the most recent
design value (including and excluding the event-affected data), and
basic information specific to each monitored day. Other commenters
indicated that the content of the Initial Notification should not be
specified. While we are not specifying required content in regulatory
language, we are providing example content of an Initial Notification
in this preamble. We also note that individual EPA Regional offices may
implement procedures within their regions to assist with event

identification, prioritization and processing.
    Regarding communications between the EPA and affected air agencies,
one commenter encouraged the EPA to ensure communication is formalized
in writing and clarify that the EPA should initiate conversations
regardless of the ``completeness'' of the notification to avoid
confusion about whether the EPA has received the notification. Another
commenter asked that we include regulatory language requiring that the
EPA negotiate a timeline for demonstration submittal based on the
available (and sometimes very limited) resources of the affected air
agency. We interpret this comment to mean that the ``negotiation''
requirement would be a requirement for air agency agreement on the
timeline for submittal rather than a consultation on timing.
    The EPA agrees with the commenter that decisions or specific
direction provided or agreed to between the EPA Regional office and the
affected air agency should be communicated in writing either by letter
or email. By decisions or direction, we generally mean decisions
regarding whether a potential event has regulatory significance
(including the EPA's intent with respect to review), direction
regarding specific event day(s) to pursue and/or information to include
in a demonstration and decisions related to target dates for
demonstration submittal. The EPA also agrees that we should acknowledge
receipt, in writing, of any submitted written Initial Notification. We
do not, however, agree with the other commenter's suggestion to include
regulatory language requiring a negotiated timeline for demonstration
submittal based on the available resources of the affected air agency.
First, such a regulatory requirement would not provide for an outcome
should the negotiations between the air agency and the EPA Region
office fail to reach agreement. Also, an air agency's failure to meet a
regulatory deadline could have different consequences than an air
agency's failure to meet an EPA-identified target date. As we noted in
the proposal and this preamble, the EPA will establish a target date
for demonstration submittal, which the EPA will communicate in writing,
after discussing the specifics of the potential event with the affected
air agency and after considering the nature of the event, the
anticipated timing of the regulatory decision, the target date for
demonstration submittal proposed by the air agency as part of its
Initial Notification (if provided), and the available time for both the
air agency's preparation of the demonstration and the EPA's review. We
believe this process adequately addresses the commenter's concerns
without the need for regulatory text.
6. Submission of Demonstrations
a. Summary of Proposal
    With respect to the submission of demonstrations, the EPA proposed
to make the following changes to the regulatory language in 40 CFR
50.14(c)(3):
     Remove the general schedule provisions in 40 CFR
50.14(c)(3)(i) for submitting demonstrations.
     Move the language requiring an air agency to include the
comments it received during the public comment period for the subject
demonstration from 40 CFR 50.14(c)(3)(i) to (v).
     Modify the language at 40 CFR 50.14(c)(3)(iv) to more
clearly identify the required elements of an exceptional events
demonstration to include (1) a narrative conceptual model and (2)
demonstrations and analyses that address the core statutory technical
criteria.
     Modify the language at 40 CFR 50.14(c)(3)(v) to identify
that a demonstration submittal must include (1) documentation that the
air agency conducted a public comment process on its draft exceptional
events demonstration that was a minimum of 30 days, which could be
concurrent with the EPA's review, (2) any public comments received
during the public comment period and (3) an explanation of how the air
agency addressed the public comments.
    As described in more detail in the proposed rule, the EPA proposed
to remove the provision in 40 CFR 50.14(c)(3)(i) that requires air
agencies to submit a demonstration ``not later than the lesser of 3
years following the end of the calendar quarter in which the flagged
concentration was recorded or 12 months prior to the date that a
regulatory decision must be made by EPA.'' In place of this language,
the EPA proposed to rely on the documentation submission schedule that,
at the time of the proposal, appeared as Table 1 at 40 CFR
50.14(c)(2)(vi) in those cases where the data are to be used in initial
area designations. If the data could influence a regulatory
determination other than an initial area designation, the EPA proposed
to rely on the case-by-case timelines established by the reviewing EPA
Regional office as part of the Initial Notification of Potential
Exceptional Event process. As we noted when discussing removing the
deadlines associated with initial event flagging in Section IV.G.4 of
this preamble, air agencies have previously expressed concern that the
timelines for event flagging and demonstration submittal are not always
appropriate because an air agency may not know that data influenced by
an exceptional event caused the design value exceedance until 3 years
after the event occurred.\103\ The EPA has previously acknowledged that
this scenario can and does occur, particularly for annual standards and
when a regulatory decision is based on a design value that is averaged
over 3 years.
---------------------------------------------------------------------------

    \103\ Responses to Significant First-Round Comments on the Draft
Guidance Documents on the Implementation of the Exceptional Events
Rule, U.S. EPA, June 2012. Available in Docket No. EPA-HQ-OAR-2011-
0887.
---------------------------------------------------------------------------

    With respect to the public comment provisions for a developed
demonstration, the EPA proposed to move the language requiring an air
agency to include the comments it received during the public comment
period for the subject demonstration from 40 CFR 50.14(c)(3)(i) to (v)
to consolidate the required elements of the public comment process for
exceptional events demonstrations within a single regulatory provision.
The proposal noted that the language at 40 CFR 50.14(c)(3)(i) requires
that ``A State must submit the public comments it received along with
its demonstration to EPA.'' The ``public comments it received'' refer
to those obtained when the air agency follows the process outlined in
40 CFR 50.14(c)(3)(v), which requires the air agency to document, and
submit with its demonstration, evidence that it followed the public
comment process.
    Because the public comment process described in the 2007 rule did
not identify a duration for the public comment process, the EPA also
proposed to specify a minimum 30-day public comment process, which
provides sufficient time for exchange between the reviewing public and
the air agency. We noted that shorter comment periods may not provide
necessary time for the public to research the identified event and
associated supporting data while longer timeframes may not be possible
where a near-term regulatory decision relies on an exceptional events
decision. The proposal stated that in very limited cases where the air
agency is relying on exceptional events claims as part of a near-term
regulatory action, such as an initial area designation decision for a
new or revised NAAQS under a 2-year designation schedule, the public
comment period could be concurrent with the EPA's review provided the
submitting air agency sends any received public comments and

responses to the EPA by a specified date. If an air agency receives
public comment disputing the technical elements of a demonstration
during a comment period that runs concurrent with the EPA's review and
these comments result in the air agency's need to reanalyze or reassess
the validity of a claimed event, a second public comment period may be
necessary.
    The EPA also proposed to revise the language at 40 CFR
50.14(c)(3)(iv) so that it more clearly identifies the required
elements of an exceptional events demonstration. The EPA proposed that
each demonstration begin with a narrative conceptual model supported by
summary tables or maps, which summarizes the event in question and
provides context for required statutory technical criteria analyses.
The EPA further proposed, consistent with other proposed changes, that
an air agency include in its demonstration to justify data exclusion
evidence that the following statutory technical criteria are satisfied:
     The event was a human activity that is unlikely to recur
at a particular location or was a natural event.
     The event was not reasonably controllable or preventable.
     The event affected air quality in such a way that there
exists a clear causal relationship between the specific event and the
monitored exceedance or violation (supported in part by the comparison
to historical concentrations and other analyses).
    The EPA sought comment on the identified proposed changes to the
language at 40 CFR 50.14(c)(3)(i), (iv) and (v), which more clearly
identify the required elements of an exceptional events demonstration.
b. Final Rule
    As with our proposal to remove the general schedule deadlines
associated with initial event flagging, the overwhelming majority of
commenters supported our proposal to remove the general schedule
demonstration submittal deadlines contained within 40 CFR
50.14(c)(3)(i). Therefore, upon consideration of those comments and for
the reasons previously explained, we are promulgating this provision as
proposed. One commenter expressed general support for this concept
provided the deadline for demonstration submittals is not extended. In
response, we note that while the deadline for demonstration submittal
might be longer than it would have been under the previous deadline of
``the lesser of 3 years following the end of the calendar quarter in
which the flagged concentration was recorded or 12 months prior to the
date that a regulatory decision must be made by EPA,'' we are not
changing the timing of the regulatory actions in which the affected
data may be used. Many of these deadlines are statutorily established
and cannot be changed by regulation. Because the EPA is also
accountable for these statutory deadlines, the effect of this now
finalized exceptional events scheduling revision is compressing the
timeline for the EPA's review.
    The final rule will provide limited flexibility regarding the
deadline for submitting exceptional events demonstrations that are
otherwise due October 1, 2016. Given the close proximity of the Federal
Register publication date of this revised rule with the demonstration
submittal deadline for data influenced by exceptional events that could
be used in the initial area designation decisions for the 2015 Ozone
NAAQS, we are intentionally adjusting the deadline for those
demonstrations in Table 2 to Sec.  50.14 and intend for this deadline
to apply to submissions that would otherwise be due October 1, 2016.
This rule is being promulgated in advance of the October 1, 2016
deadline for the 2015 Ozone NAAQS designations, providing stakeholders
with sufficient notice of this updated submission deadline. As set
forth in Table 2 to Sec.  50.14, exceptional events demonstrations must
be submitted to the EPA on the later of (1) sixty days after the
effective date of this rule or (2) the date that state and tribal
recommendations are due to the Administrator. Going forward,
exceptional events demonstrations will be due no later than the date
that state and tribal designation recommendations are due to the
Administrator.
    We received no significant comments regarding the proposed
revisions associated with the public comment process. Therefore, for
the previously explained reasons, we are finalizing, as proposed, the
repositioning of the requirement that an air agency include any
received public comments from 40 CFR 50.14(c)(3)(i) to (v). We are also
promulgating the revised language at 40 CFR 50.14(c)(3)(v) to identify
that a demonstration submittal must include (1) documentation that the
air agency conducted a public comment process on its draft exceptional
events demonstration that was a minimum of 30 days, which could be
concurrent with the beginning of the EPA's initial review period, (2)
any public comments received during the public comment period and (3)
an explanation of how the air agency addressed the public comments. As
indicated in 40 CFR 50.14(c)(3)(v)(A), we have also finalized 30 days
as the minimum duration for a public comment period.
    We are promulgating revisions to the submission and required
elements of an exceptional events demonstration at 40 CFR
50.14(c)(3)(iv), as proposed, for the previously stated reasons and as
supported by commenters. Regarding the requirement that components of a
demonstration include a narrative conceptual model, one commenter asked
that we use the terminology ``narrative'' or ``executive summary''
rather than ``conceptual model.'' We have retained the use of narrative
conceptual model because we believe this best conveys our intent, which
is the ``story'' or ``executive summary'' of the event that provides an
overview of the technical information in the demonstration and helps
identify relevant quantitative information critical in satisfying the
Exceptional Events Rule criteria. In most cases, air agencies will
support the discussion in the narrative conceptual model with tables
and maps.
c. Comments and Responses
    We address any additional comments received on this topic in the
Response to Comments document found in the docket for this action.
7. Timing of the EPA's Review of Submitted Demonstrations
a. Summary of Proposal
    The proposal summarized and clarified some of the EPA's previous
statements regarding the prioritization and submittal of
demonstrations, and proposed regulatory language to increase the
efficiency of preparing, submitting and reviewing exceptional events
demonstrations. We did not propose any changes to regulatory language
pertaining to the timing of the EPA review process. Rather the proposal
discussed processes, expectations and communications concerns, which
are at the center of timing-related issues.
    The proposal articulated the EPA's previously expressed commitment
to work collaboratively with air agencies as they prepare complete
demonstrations. As we have previously communicated, demonstrated and
summarized in our best practices for communications,\104\ we encourage
ongoing discussions between the

reviewing EPA Regional office and the submitting air agency through the
duration of the exceptional events process beginning with the Initial
Notification of Potential Exceptional Event. Implementing the
approaches identified by air agencies has generally improved the
exceptional events process by improving relationships between air
agencies and the EPA Regional office, clarified expectations, and
resulted in decreased instances of submissions containing insufficient
or unnecessary information.
---------------------------------------------------------------------------

    \104\ Best Communication Practices for Preparation of
Exceptional Event Demonstrations, U.S. EPA, OAQPS, 2015. Available
at http://www2.epa.gov/air-quality-analysis/treatment-data-influenced-exceptional-events.
---------------------------------------------------------------------------

    The proposal clarified our continued efforts to improve the
exceptional events process, in part through improved communications but
also through regulatory changes and workload prioritization. On this
last point, the proposal identified that in reviewing submitted
demonstrations, the EPA will generally give priority to exceptional
events determinations that may affect near-term regulatory decisions,
such as the EPA's action on SIP submittals, NAAQS designations and
clean data determinations (see discussion in Section IV.C of this
preamble). The proposal stated the EPA's intent to make a decision
regarding event status expeditiously following submittal of a complete
demonstration if required by a near-term regulatory action. If during
the review process the EPA identifies the need for additional
information to determine whether the exceptional events criteria are
met, the EPA will notify the submitting air agency and encourage the
agency to provide the supplemental information. If the information
needed is minor and a natural outgrowth of what was previously
submitted, the EPA will not require the air agency to undergo an
additional public notice-and-comment process. However, if the needed
information is significant, the EPA may request that the air agency re-
notice the demonstration before resubmitting it to the EPA, thus
requiring an additional EPA review following resubmittal. The EPA will
work with air agencies on supplemental timeframes; however, the
mandatory timing of the EPA actions may limit the response time the EPA
allows. The EPA proposed to include as rule text a requirement for the
air agency to submit additional information within 12 months. If
additional information is not received in 12 months, then the EPA would
consider the submitted demonstration inactive, and would not continue
the review or take action. In effect, an air agency's lack of response
within a 12-month period would ``void'' the submittal. The proposal
stated that in these cases, the EPA would not intend to issue a formal
notice of deferral. If the air agency later decided to pursue the
exceptional events claim after a 12-month period of inactivity, it may
re-initiate the exceptional events process by submitting a new Initial
Notification of Potential Exceptional Event followed by a new
demonstration, which could simply be revising the original submittal to
include the additional information previously requested by the EPA.
    The proposal explained that at the conclusion of the EPA's review,
the EPA would make a determination regarding the status of a submitted
exceptional events demonstration. The EPA's decision could result in
concurrence, nonconcurrence or deferral.\105\ In acting on a submitted
demonstration covering multiple event days and/or multiple flags, the
EPA could concur with part of a demonstration and nonconcur or defer
other flagged values. If the EPA determined that the events addressed
in an exceptional events demonstration are not anticipated to affect
any future regulatory decision, the EPA could defer review of these
events and notify the submitting agency if a subsequent review results
in a determination that the events would affect a regulatory
decision.\106\ The proposal stated that formal mechanisms for deferral
could include the EPA's indicating this decision by letter, by email to
a responsible official or during a high-level meeting with an attendees
list and discussion summary.
---------------------------------------------------------------------------

    \105\ The EPA anticipates a reduced number of deferrals and/or
nonconcurrences for demonstrations associated with the Initial
Notification of Potential Exceptional Event process as discussed in
Section IV.G.5 of this preamble because the EPA and the affected air
agency would have discussed issues/concerns prior to the EPA's
decision on a submitted demonstration.
    \106\ Routine status calls between the reviewing EPA Regional
office and air agencies could include an agenda item to review the
status of all submitted demonstrations, including those that the EPA
has deferred.
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b. Final Rule
    For the previously explained reasons and as supported by one
commenter, the EPA is finalizing with some clarification to the
proposed language, the regulatory provision at 40 CFR 50.14(c)(3)(vi)
to cease review of a demonstration following a 12-month period of
inactivity by the submitting air agency. This finalized provision would
apply when the air agency has submitted a demonstration for which the
EPA has requested additional information, as indicated in writing by
letter or email. The air agency will have 12 months from the date of
the EPA's request to respond with the requested information. The EPA
intends to track progress on demonstrations with regulatory
significance and this 12-month period will ensure air agency
accountability for its demonstrations and will allow the EPA to
appropriately prioritize resources. Although the EPA anticipates
ongoing discussions with the air agency, if the EPA has not received
information from the air agency in response to the EPA's request for
additional information, then least a month before the expiration
period, the EPA will remind the air agency in writing (e.g., a letter
or email) of the upcoming deadline. The EPA will work with individual
air agencies to address those situations where a response is
insufficient or where an air agency needs additional time to prepare
needed analyses or assemble identified information. If the air agency
has not responded within this 12-month timeframe, then the EPA's review
of the demonstration will terminate. The EPA can provide notification
of such termination by sending written notification (e.g., a letter or
email) to the affected air agency.
    Although we are not promulgating timelines in rule language for the
EPA's response to demonstrations, we are identifying here the response
timelines that we intend to follow during the Initial Notification and
demonstration review processes. As we stated in Section IV.G.5.b of
this preamble, the EPA intends to acknowledge receipt shortly after
receiving an air agency's Initial Notification and then formally
respond to the Initial Notification within 60 days. The EPA response
will provide the EPA Regional office's best assessment of the priority
that can be given to the submission once received, any case-specific
advice the EPA may have to offer for the preparation of the
demonstration, and the target date for demonstration submittal.
    The EPA generally intends to conduct its initial review of an
exceptional events demonstration with regulatory significance within
120 days of receipt. This initial review could be extended in certain
circumstances, such as if the EPA is reviewing a demonstration
concurrent with an air agency's public comment period. Following this
initial review, the EPA will generally send a letter or email to the
submitting air agency that includes a completeness determination and/or
a request for additional information, a date by which the supplemental
information should be submitted (if applicable), and an indicator of
the timing of the EPA's final review. The EPA intends to make a
decision regarding event concurrence as

expeditiously as necessary if required by a near-term regulatory
action, but no later than 12 months following submittal of a complete
demonstration.
    In addition, if an air agency submits a demonstration for an event
not discussed in the Initial Notification process or that the EPA has
determined during the Initial Notification process to not to have
regulatory significance (and there is no other compelling reason for
excluding data), then the EPA will ``close out'' a submitted
demonstration with a ``deferral letter'' within 60 days of receipt of
the demonstration.
c. Comments and Responses
    Numerous commenters asked that the EPA promulgate deadlines by
which the EPA must act on exceptional events demonstrations. We are
accountable for many statutorily-established deadlines for regulatory
action. We also note that promulgating timelines for action might not
have the intended result of expediting the EPA's action because it
could force both the air agencies and the EPA to focus their efforts
and limited resources on demonstrations that ultimately have no
regulatory significance. Or, promulgated timelines could cause the EPA
to act on determinations in the order in which they were received
instead of allowing the EPA to prioritize demonstrations for nearer-
term regulatory actions or mandated regulatory actions.
    Establishing regulatory deadlines also implies consequences for
missing such deadlines. Three commenters have suggested that the EPA's
failure to act on a submitted demonstration within a promulgated
timeframe should result in automatic approval of the subject
demonstration. The EPA's inaction cannot be assumed to be approval of a
demonstration. By statute in CAA section 319(b), exceptional events
must satisfy certain definitional and procedural requirements,
including a determination by the Administrator. These CAA criteria
cannot be presumed to be satisfied unless the Administrator
concurs.\107\ Inaction is not concurrence. Additionally, approval by
default is not appropriate because it would not ensure that air
agencies and the EPA are upholding the principles and requirements of
CAA section 319(b). Specifically, automatic approval of a demonstration
without adequate review would not ensure that air agencies are taking
appropriate and reasonable actions to protect public health from
exceedances or violations of the NAAQS. Another consequence of missing
a promulgated deadline could be the opportunity for an air agency, or,
potentially, another interested party, to file a lawsuit. This action
is also not likely to expedite a decision on a given demonstration.
---------------------------------------------------------------------------

    \107\ As discussed in more detail in Section IV.G.7 of this
preamble, concurrent with these rule revisions, the EPA has revised
the delegation of authority for exceptional events decision making.
These authorities were previously delegated to the EPA Regional
Administrators and, under the revised delegation, may be redelegated
from the EPA Regional Administrator to the Regional Air Division
Director or equivalent highest manager who exclusively oversees air
programs.
---------------------------------------------------------------------------

    While we are not promulgating timelines in rule language for EPA's
action, this preamble identifies the response timelines that we intend
to follow during the Initial Notification and demonstration review
process. Further, we have finalized provisions that focus on
exceptional events demonstrations that have regulatory significance,
which means that the demonstrations affect the outcome of a regulatory
action. We are committed to taking action on all submitted
demonstrations that have regulatory significance.
    Two commenters expressly supported the EPA's approach to
prioritizing exceptional events demonstrations to focus on those that
affect regulatory determinations. Several other commenters indicated
their belief that the EPA should act on all submitted demonstrations.
Regarding acting on all demonstrations, we have taken numerous steps in
this action and otherwise to improve the exceptional events process and
we maintain that, given limited resources, both the air agencies' and
the EPA's efforts should focus on the development and review of those
demonstrations that affect regulatory determinations. Expending time
and energy on demonstrations that will not influence the outcome of a
regulatory action is generally not an efficient use of resources. As we
have indicated in numerous passages in this final action, we will
consider exceptional events demonstrations on a case-by-case basis and
air agencies will have an opportunity to state their position during
the Initial Notifications process. Unless there is a compelling reason,
we will ``close out'' those demonstrations that we receive, which were
not discussed in the Initial Notification process or those which the
EPA has determined during the Initial Notification process do not have
regulatory significance.
    Another commenter asks that the EPA ``grandfather'' or otherwise
respond to those demonstrations that have been previously submitted but
on which the EPA has not yet acted. In promulgating these final rule
revisions, we are taking no actions with respect to previously
submitted and unprocessed demonstrations that otherwise remain
``open.'' To request a response for an inactive demonstration, we ask
that the affected air agency contact the reviewing EPA Regional office
and inquire as to the most appropriate next steps.
    Two commenters supported, and several opposed, the EPA's regulatory
provision to terminate the EPA's obligation to review a demonstration
following a 12-month period of inactivity by the air agency. One of
these supporters asked that, to facilitate transparency, that the EPA
develop a publicly-accessible and transparent tracking system or
otherwise provide status updates. The EPA agrees that a national
tracking system could be valuable. We intend to explore this concept
further as we implement these rule revisions.
8. Dispute Resolution Mechanisms
    In the November 2015 proposal, the EPA discussed currently
available dispute resolution mechanisms but neither proposed any
associated regulatory language nor solicited comment on the dispute
resolution process. Rather, the proposal explained that there is no
need for a formal dispute resolution mechanism for exceptional events
for the following reasons: (1) The existing dispute resolution
mechanisms are sufficient, (2) the EPA is committed to focusing on
communication and collaboration with the submitting air agency through
the exceptional events demonstration process, and (3) this final action
includes useful clarifications that should reduce disagreements between
air agencies and the EPA regarding the adequacy of demonstrations.
    Despite our statement that we were not soliciting comment of the
topic of dispute resolution, numerous commenters requested that the EPA
promulgate a dispute resolution process. Although commenters specified
that the process be ``judicially appealable,'' ``include an independent
third party with technical expertise'' and/or ``involve multiple EPA
decision makers,'' no commenters provided substantive suggestions as to
the mechanism by which a dispute resolution process could be
implemented. In this action, we are not promulgating a dispute
resolution mechanism. We are, however, restating currently available
elevation measures and the EPA's internal mechanisms that ensure
regional consistency.
    As noted in the proposal, several mechanisms currently exist that
air agencies can use at various points in the

exceptional events process. These mechanisms include engaging in early
dialogue with the reviewing EPA Regional office, submitting requests
for reconsideration to the official who made the determination if a
request identifies a clear error or if the reviewing EPA Regional
office overlooked information submitted by the affected air agency,
and/or elevating the concern within the EPA's chain of command.
Additionally, air agencies can raise any unresolved event-related
issues during the regulatory process that relies upon the claimed
event-influenced data by participating in related public notice-and-
comment processes and/or challenging in an appropriate court the
regulatory decision subsequently made based in part on the EPA's
exceptional events determination.
    The EPA did not specifically identify in the proposal some of the
internal steps we have taken to improve our ability to act on
exceptional events activities and actions in a timely and efficient
manner. First, we have expanded the number of officials within the EPA
who can make exceptional events decisions. While the language of CAA
section 319(b) states that decision making on exceptional events is a
process undertaken by the Administrator, our promulgation of the 2007
Exceptional Events Rule was accompanied by a delegation of authority
delegating the decision making for exceptional events from the
Administrator to the Assistant Administrator for Air and to the EPA
Regional Administrators. However, this delegation did not allow for
final decision making below the EPA Regional Administrator level. As
part of this rule revision process, we revised the delegation of
authority for exceptional events to allow for redelegation from the EPA
Regional Administrator to the EPA Regional Air Division Director or
equivalent highest manager who exclusively oversees air programs. If an
EPA Regional Administrator elects to pursue redelegation, then the EPA
Regional Air Division Director (or equivalent manager) would make
exceptional events decisions and the EPA Regional Administrator would
be an additional resource available within the elevation process for an
air agency wishing to elevate concerns regarding an exceptional events-
related decision.
    The proposal also did not explain the role of the EPA's National
Exceptional Events Work Group. This work group consists of technical
and policy staff within the EPA's Office of Air Quality Planning and
Standards (OAQPS), each of the EPA's Regional offices and the EPA's
Office of General Counsel. The work group typically meets once each
month and discusses technical and policy issues regarding exceptional
events, including best practices implemented within the regions, new or
evolving tools and technologies to help identify events and assess
their impacts, upcoming regulatory decisions that could be influenced
by event determinations and opportunities for outreach. In addition, at
each meeting, regional participants report on the status of exceptional
events actions in their respective states. This event report out also
includes a discussion of new event types and/or novel policy issues and
provides an opportunity for regional and OAQPS review of and input on
specific demonstrations. These collaborative reviews are particularly
relevant for new events (such as for the 2012 Wyoming Stratospheric
Ozone Intrusion).\108\
---------------------------------------------------------------------------

    \108\ Wyoming Department of Environmental Quality, Air Quality
Division. Big Piney and Boulder, Wyoming Ozone Standard Exceedance,
June 14, 2012. Available at http://www2.epa.gov/air-quality-analysis/exceptional-events-submissions-table.
---------------------------------------------------------------------------

    As noted in the proposal, with exceptional events decisions, the
air agency has opportunities to elevate concerns during two processes:
The exceptional events determination and the subsequent regulatory
action that relies on the exceptional events decision.

V. Mitigation

    Section 319(b)(3)(A) of the CAA identifies five principles that the
EPA must follow in developing implementing regulations for exceptional
events:

    (i) Protection of public health is the highest priority;
    (ii) Timely information should be provided to the public in any
case in which the air quality is unhealthy;
    (iii) All ambient air quality data should be included in a
timely manner in an appropriate federal air quality database that is
accessible to the public;
    (iv) Each state must take necessary measures to safeguard public
health regardless of the source of the air pollution; and
    (v) Air quality data should be carefully screened to ensure that
events not likely to recur are represented accurately in all
monitoring data and analyses.

    The regulatory requirements implementing (iii) and (v) of this part
of the statute are found in 40 CFR 50.14 while the regulatory
requirements implementing (i) and (iv) are found in 40 CFR 51.930,
Mitigation of Exceptional Events. Both Sec. Sec.  50.14(c)(1) and
51.930(a)(1) implement (ii) of this part by requiring states to provide
notice of events to the public.
    The EPA promulgated the ``mitigation'' measures \109\ at 40 CFR
51.930 when we finalized the Exceptional Events Rule in 2007, but we
did not incorporate these measures into the criteria and processes by
which data are excluded from use in regulatory determinations. The
provisions at 40 CFR 51.930 require air agencies requesting data
exclusion to take appropriate and reasonable actions to protect the
public health from exceedances or violations of the NAAQS, promptly
notify the public when the air exceeds or is expected to exceed the
NAAQS, and educate the public regarding steps they can take to minimize
exposure. These requirements apply whenever an air agency requests data
exclusion, regardless of whether the EPA approves the exclusion.
Although air agencies submitting demonstrations must meet the
requirements at 40 CFR 51.930, the provisions do not require air
agencies to submit their identified measures to the EPA or to notify
the EPA of the measures an air agency plans to take or has taken. The
mitigation measures that the EPA has seen air agencies practicing most
commonly are those related to the requirement that air agencies
``provide for prompt public notification whenever air quality
concentrations exceed or are expected to exceed the NAAQS.'' Often,
these public notifications have included public health alerts for high
wind dust events or wildfires. Other aspects of mitigation, including
implementing appropriate measures to protect public health beyond
notification, are also important in implementing the CAA guiding
principle that ``each State must take necessary measures to safeguard
public health regardless of the source of the air pollution.''
---------------------------------------------------------------------------

    \109\ The term ``mitigation'' does not appear in CAA section
319(b). It appears in the title but not the text of 40 CFR 51.930.
---------------------------------------------------------------------------

A. Summary of Proposal

    The proposal identified several possible changes to the mitigation-
related rule components and solicited comment on approaches ranging
from retaining the existing rule requirements at 40 CFR 51.930 to
including several new components. The proposal indicated that as a
result of commenter feedback, we might make no changes, adopt all of
the presented components, or adopt some of the described features. The
proposal also indicated that, if finalized, the identified mitigation
components, which would be an obligation for an affected air agency and

serve as criteria for the EPA's approval of future exceptional events
demonstrations, would only apply to those air agencies with areas
subject to ``historically documented'' or ``known seasonal''
exceptional events.
1. Defining Historically Documented or Known Seasonal Events
    The proposal accepted comment on whether to define ``historically
documented'' or ``known seasonal'' exceptional events to include events
of the same type and pollutant (e.g., high wind dust/PM or wildfire/
ozone) that recur on an annual or seasonal basis and meet any of the
following criteria: An event for which an air agency has previously
submitted exceptional events demonstrations; an event that an air
agency has previously flagged for concurrence in AQS (regardless of
whether the air agency submitted a demonstration); or an event that has
been the subject of public health alerts or published scientific
journal articles. The proposal indicated that the EPA would not require
an air agency to develop a mitigation plan for the first event of a
given type (e.g., if an area is prone to wildfires but has never
experienced a high wind dust event, then it would not be expected to
develop a mitigation plan for its first high wind dust event, but it
would be expected to develop a mitigation plan for wildfires). A second
event of a given type within a 3-year period would subject the area to
``having a history'' and, therefore, needing a mitigation plan.\110\
This option avoids plan development following a one-of-a-kind
occurrence.\111\ In defining ``first'' and ``second'' events, the EPA
indicated that it could consider events that affect the same AQCR, but
not necessarily the same monitor.\112\ We also solicited comment on
whether it would be appropriate to consider a season of multiple events
of a common type as one of three required seasons, so that a mitigation
plan would be required only when an event type persists across several
years.
---------------------------------------------------------------------------

    \110\ A 3-year period is measured backwards from the date of the
most recent event.
    \111\ Because the form of the NAAQS varies by pollutant, it is
possible that multiple events in a 3-year period may not cause a
NAAQS violation. An air agency that identifies multiple events of
the same type (e.g., wildfire/ozone) in AQS, but prepares and
submits a demonstration for only one of these events, would trigger
the proposed requirement to develop a mitigation plan.
    \112\ 40 CFR part 81, subpart B, Designation of Air Quality
Control Regions, defines Air Quality Control Regions.
---------------------------------------------------------------------------

2. Mitigation Plan Components
    The proposal also identified and solicited comment on the following
three plan components that could be recommended or required to
implement the mitigation principles found in CAA section 319(b)(3)(A):
Public notification and education; steps to identify, study and
implement mitigating measures; and provision for periodic revision of
the mitigation plan (to include public review of plan elements). Given
the identified components, the proposal solicited comment on
appropriate timelines for submitting a plan.
3. Options for Implementing Mitigation Plans
    Because the 2007 Exceptional Events Rule did not tie the mitigation
elements at 40 CFR 51.930 to the EPA's review of exceptional events
demonstrations, we proposed and solicited feedback on the following
options: Option 1 included the EPA's review for completeness but not
substantive approval or disapproval, while Option 2 included the EPA's
approval of the substance of the mitigation plan. The proposal noted
that neither option would require a mitigation plan to be included in a
SIP or to be otherwise federally-enforceable. Regarding the submittal
of a mitigation plan to the EPA, the EPA proposed that air agencies
with historically documented or known seasonal exceptional events could
submit the mitigation plan to the EPA in advance of an event, or submit
a mitigation plan along with an exceptional events demonstration. For
both options, the proposal explained that if the EPA otherwise
concurred with an exceptional events demonstration for a type of event
that is also the subject of the mitigation plan, the EPA would only
concur with such a demonstration for the relevant event type if a
mitigation plan passed the type of review described in the option
(i.e., completeness review for Option 1 or approval of content for
Option 2).

B. Final Rule

    In keeping with the EPA's mission to protect public health and
consistent with the principles included at CAA section 319(b)(3)(A),
and after consideration of the public comments, we are promulgating new
mitigation-related regulatory language at 40 CFR 51.930 requiring the
development of mitigation plans in areas with ``historically
documented'' or ``known seasonal'' exceptional events. As part of these
promulgated requirements, we have decided to follow the review option
identified as Option 1 in the proposal, which includes the EPA's review
and a completeness determination, but not the EPA's ``approval'' of the
plan content (identified as Option 2 in the proposal), as discussed in
the comments and responses section below. We believe this option
maximizes the flexibility of the air agency while providing for the
protection of public health through the EPA's review of the required
plan content and through the required public review process. We further
believe that Option 2, which required the EPA's approval of mitigation
plan content, could have the unintended effect of imposing additional
administrative burden (e.g., multiple rounds of review and revision)
without corresponding additional public health and air quality benefit.
Other regulatory mechanisms are already available to address public
health and air quality, as needed (e.g., SIP revisions or the
regulatory action that is the focus of an event of the type that is the
subject of the mitigation plan and an exceptional events
demonstration). We are also adding a provision to clarify that, after
an initial implementation period (as discussed in Section V.B.3 of this
preamble), the EPA will not concur with an air agency's request to
exclude data that have been influenced by an event of the type that is
the subject of a required mitigation plan if an air agency has not
submitted the related required mitigation plan. The EPA could, however,
either nonconcur or defer action on a demonstration for such event-
influenced data. The EPA's action would likely depend on the timing of
the associated regulatory action. We are promulgating this regulatory
language after seeking comment on approaches ranging from retaining the
existing ``mitigation'' rule requirements to promulgating new
mitigation-related rule components.
1. Defining Historically Documented or Known Seasonal Events
    We are defining ``historically documented'' or ``known seasonal''
events to include events of the same type and pollutant (e.g., high
wind dust/PM or wildfire/ozone) that recur every year, either
seasonally or throughout the year. For purposes of identifying the
bounds of ``a particular area'' for those areas that are initially
subject to the requirement to develop a mitigation plan (as discussed
later in this section), we are using nonattainment area boundaries or
county boundaries for those areas not in a nonattainment area. After
these initial areas for which we have identified boundaries, the EPA
Regional office and the affected air

agencies should consult regarding how to characterize ``a particular
location.'' Ultimately, the EPA will determine the bounds for ``a
particular location.''
    Regarding recurrence, we are using the benchmark of three events in
3 years, which applies regardless of an area's designation status with
respect to the NAAQS that could be the focus of a potential
demonstration for a recurring event and regardless of whether the event
type is the focus of specific recurrence circumstances within this rule
for the ``human activity unlikely to recur at a particular location or
a natural event'' criterion. We measure the 3-year period backwards
from the date of the most recent event. Similar to our discussion of
recurrence for the ``human activity unlikely to recur'' criterion in
Section IV.E.1 of this preamble, if there have been two prior events of
a similar type (i.e., a similar event type generating emissions of the
same pollutant) within a 3-year period in ``a particular location,''
the third event constitutes recurrence. While we are using the
benchmark of three events in a 3-year period, for purposes of
``historically documented'' or ``known seasonal'' events, we will treat
a season with multiple events as one event such that a mitigation plan
will be required only when an event type persists across several years.
For example, an area may not have previously experienced wildfires in
the past 10 years, but then experiences multiple wildfires and multiple
exceedances in a single wildfire season. If these multiple wildfires
affect the same general geographic area and monitors in a relatively
short period of time (e.g., 2-3 months), then they could be considered
a single event for purposes of developing a mitigation plan and would
not trigger the requirement for a mitigation plan. Also, for purposes
of counting a season towards the limit of three seasons in 3 years, we
mean a season containing one or more events for which an air agency has
previously submitted exceptional events demonstrations or a season of
events that is the subject of an Initial Notification of Potential
Exceptional Event as discussed in Section IV.G.5 of this preamble
(regardless of whether the air agency submitted a demonstration).\113\
Where an area experiences multiple event seasons in a given year (e.g.,
a spring season and a fall season of events), then each season will
count towards the benchmark of three recurrences in 3 years. Under this
scenario, an area could experience a single season of events in year
one, no events in year two, and multiple seasons of events in year
three. Using the benchmark of three event-containing seasons in 3 years
would subject the area to ``having a history'' and, therefore, needing
a mitigation plan. The requirements of this section will apply
regardless of the event/pollutant combination and regardless of whether
the event type is the focus of specific recurrence circumstances within
this rule for the ``human activity unlikely to recur at a particular
location or a natural event'' criterion. We note, however, a
demonstration for an event (or event season) for which the EPA
nonconcurs (or previously nonconcurred) will not count towards
recurrence.
---------------------------------------------------------------------------

    \113\ Because the Initial Notification of Potential Exceptional
Event is a new requirement in this action, we cannot use it to
define recurrence for those areas that are initially subject to the
requirement to develop a mitigation plan. For these areas, we are
defining recurrence as three events or event seasons for which an
air agency submitted a demonstration within a 3-year period or three
events or event seasons in a 3-year period that resulted in a NAAQS
exceedance(s) or violation(s) for which an air agency has previously
flagged events for concurrence in AQS (regardless of whether the air
agency submitted a demonstration).
---------------------------------------------------------------------------

    Applying this framework of three events (or three seasons with
multiple events of a common type) in a 3-year period, we identify in
Table 6 those areas that have experienced recurring events during the
timeframe from January 1, 2013, through December 31, 2015. Per the
requirements set forth in 40 CFR 51.930(b)(1)(ii), we are using this
action to provide written notice that the areas identified in Table 6
need to submit mitigation plans according to the requirements of the
rule provisions in 40 CFR 51.930(b).

                  Table 6--Areas Subject to the Mitigation Requirements in 40 CFR 51.930(b) \a\
----------------------------------------------------------------------------------------------------------------
                                                         AQS Flag                          Nonattainment area,
            Pollutant               AQS Flag \b\        description          State       county or city boundary
----------------------------------------------------------------------------------------------------------------
Ozone...........................  RO                Stratospheric       CO               Denver-Boulder-Greeley-
                                                     Ozone Intrusion.                     Ft. Collins-Loveland,
                                                                                CO Ozone Nonattainment
                                                                                Area
Ozone...........................  RT                Wildfire-U. S.....  CO               Denver-Boulder-Greeley-
                                                                                Ft. Collins-Loveland,
                                                                                CO Ozone Nonattainment
                                                                                Area
Ozone...........................  RT                Wildfire-U. S.....  NV               Clark County
PM10............................  RJ                High Winds........  AZ               Phoenix, AZ PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  AZ               Rillito, AZ PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  AZ               West Pinal, AZ PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  AZ               Yuma, AZ PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  AZ               Gila River Indian
                                                                                Community
PM10............................  RJ                High Winds........  AZ               Salt River Pima-
                                                                                Maricopa Indian
                                                                                Community
PM10............................  RJ                High Winds........  CA               Coso Junction, CA PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  CA               Imperial Valley, CA
                                                                                PM10 Nonattainment
                                                                                Area
PM10............................  RJ                High Winds........  CA               Coachella Valley, CA
                                                                                PM10 Nonattainment
                                                                                Area
PM10............................  RJ                High Winds........  CA               San Joaquin Valley PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  CA               Los Angeles South Coast
                                                                                Air Basin PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  CO               Alamosa County
PM10............................  RJ                High Winds........  CO               Prowers County
PM10............................  RJ                High Winds........  NM               Anthony, NM PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  NM               Luna County
PM10............................  RJ                High Winds........  NV               Nye County
PM10............................  RJ                High Winds........  NV               Clark County PM10
                                                                                Nonattainment Area
PM10............................  RJ                High Winds........  WA               Wallula PM10
                                                                                Maintenance Area
PM2.5...........................  RA                African Dust......  TX               Harris County
PM2.5...........................  RJ                High Winds........  TX               El Paso County
PM2.5...........................  RS                Volcanic Eruptions  HI               Hawaii County
PM2.5...........................  RT                Wildfire-U. S.....  CA               Nevada County
PM2.5...........................  RT                Wildfire-U. S.....  CA               Sacramento, CA PM2.5
                                                                                Nonattainment Area

PM2.5...........................  RT                Wildfire-U. S.....  MT               Missoula County
PM2.5...........................  RT                Wildfire-U. S.....  MT               Ravalli County
PM2.5...........................  RT                Wildfire-U. S.....  NV               Carson City (City)
PM2.5...........................  RT                Wildfire-U. S.....  NV               Douglas County
PM2.5...........................  RT                Wildfire-U. S.....  NV               Washoe County
SO2.............................  RS                Volcanic Eruptions  HI               Hawaii County
----------------------------------------------------------------------------------------------------------------
\a\ The areas noted in this table were identified using monitoring data in AQS for the January 1, 2013, through
  December 31, 2015, timeframe. The EPA downloaded data with request exclusion flags in May 2016, matched these
  data to exceedance days and then identified those areas with three seasons of events within a 3-year period.
\b\ The complete list of AQS qualifier codes and descriptions is available at https://aqs.epa.gov/aqsweb/documents/codetables/qualifiers.html.

    An area that appears in Table 6 for multiple NAAQS and/or event
types could have a single mitigation plan, provided the plan components
and actions address the multiple NAAQS and events. For example, a few
areas have recurring high wind dust events for both PM10 and
PM2.5. These areas could develop a single high wind dust
mitigation plan that addresses both PM10 and
PM2.5.
    Within 2 years of the effective date of this action, air agencies
responsible for ensuring air quality for the identified areas shall
submit mitigation plans to the applicable EPA Regional Administrator.
After this 2-year timeframe, the EPA will not concur with an air
agency's request to exclude data that have been influenced by an event
of the type that is the subject of a required mitigation plan if an air
agency has not submitted the related required mitigation plan. The EPA
could, however, either nonconcur or defer action on a demonstration for
such event-influenced data. The EPA's action would likely depend on the
timing of the associated regulatory action. As other areas become
subject to the mitigation requirements identified in this action, the
EPA will notify such areas in writing of the need for a mitigation
plan. We discuss the timing associated with implementing a mitigation
plan in more detail in Section V.B.3 of this preamble.
2. Mitigation Plan Components
    After considering the public comments we received, we are
finalizing the following three required plan components to help
implement the mitigation principles found in CAA section 319(b)(3)(A).
Unless otherwise specified, each mitigation plan should address actions
that would be taken within an air agency's own jurisdiction for events
that happen within its own jurisdiction or within the jurisdiction of
another air agency.
    a. Public notification to and education programs for affected or
potentially affected communities. Air agencies are required to include
in their mitigation plans steps to activate public notification and
education systems whenever air quality concentrations exceed or are
expected to exceed an applicable short-term NAAQS.\114\ If possible,
air agencies would notify the public of the actual or anticipated event
at least 48 hours in advance of the event using methods appropriate to
the community being served. (The EPA recognizes that for some event
types, a 48-hour advance notice may not be possible.) Outreach
mechanisms could include: Web site alerts, National Weather Service
alerts, telephone or text bulletins, television or radio campaigns or
other messaging campaigns. Public notification and education programs
should include some or all of the following actions to support the
outreach system: Adoption of methods for forecasting/detection,
consultation with appropriate health department personnel regarding
issuing health advisories and suggested actions for exposure
minimization for sensitive populations (e.g., remain indoors, avoid
vigorous outdoor activity, avoid exposure to tobacco smoke and other
respiratory irritants and, in extreme cases, evacuation or public
sheltering procedures).
---------------------------------------------------------------------------

    \114\ By short-term, we mean NAAQS with averaging times that are
24-hours or less. We do not believe it is appropriate to notify the
public when the pollutant concentrations exceed or violate a 3-month
rolling average or an annual average as these violations reflect
cumulative effects and in many cases the cause of the exceedance or
violation is long past.
---------------------------------------------------------------------------

    b. Steps to identify, study and implement mitigating measures,
including approaches to address each of the following:
    (i) Mandatory or voluntary measures to abate or minimize
contributing controllable sources of identified pollutants that are
within the jurisdiction of the affected air agency. An air agency is
encouraged to consider full-time or contingent controls on event-
related sources as well as non-event related sources. For example,
these measures might include continuously operating control measures
during an extreme event for identified sources that normally operate
these same controls on an intermittent basis. It could also involve
including work practices (e.g., water spray for dust suppression) or
contingent limits during extreme events on emissions from non-event
related sources that, under non-event periods, have no or less
stringent emissions limits or work practices.
    (ii) Methods to minimize public exposure to high concentrations of
identified pollutants.
    (iii) Processes to collect and maintain data pertinent to the event
(e.g., to identify the data to be collected, the party responsible for
collecting and maintaining the data and when, how and to whom the data
will be reported).
    (iv) Mechanisms to consult with other air quality managers in the
affected area regarding the appropriate responses to abate and minimize
impacts. Consultation could include collaboration between potentially
affected local, state, tribal and federal air quality managers and/or
emergency response personnel.
    c. Provisions for review and evaluation of the mitigation plan and
its implementation and effectiveness by the air agency and all
interested stakeholders (e.g., public and private land owners/managers,
air quality, agriculture and forestry agencies, the public). During the
initial development of the mitigation plan, this public review process
would follow a process similar to that required for the public review
of an exceptional events demonstration. That is, to solicit feedback
from interested parties, an air agency subject to the mitigation
requirements would conduct a public comment process on a draft
mitigation plan for a minimum of 30 days. The air agency would then
submit the public comments received to the EPA with the air agency's
submission of its final

mitigation plan. With this submission and for each public comment
received, the air agency would explain the changes made to the
mitigation plan or explain why the air agency did not make any changes
to the mitigation plan. We believe that public feedback will inherently
strengthen the mitigation plans and focus the air agency action in the
areas most needing the attention. Air agencies and the affected public
are better suited than the EPA to determine effective mitigation
measures.
    The EPA expects that once an area becomes subject to these
mitigation requirements, it will always have a mitigation plan in
effect, although the plan would be periodically revised and evaluated
for effectiveness. The process by which the air agency accomplishes
this periodic review and evaluation of plan effectiveness after the
initial development of the plan must also be identified in the plan.
The review and evaluation would necessarily include a public process to
solicit feedback from interested stakeholders (e.g., public and private
land owners/managers, air quality, agriculture and forestry agencies,
the public). Periodic review could follow a process similar to the one
identified for initial plan development. Although the air agency can
determine the review timeframe for a mitigation plan, we offer the
following guidance. For example, within this section of a mitigation
plan, the air agency could specify review and revision, if appropriate,
and recertification of the mitigation plan every 3 years. The air
agency could also identify that review, revision, and recertification
would occur after a season of implementing the plan, which could result
in annual review if events continued to recur with such a frequency.
Or, if the subject event did not recur for 5 years, then plan
reassessment would follow a longer timeframe.
    Because evaluating the effectiveness of a mitigation plan includes
actions and responses from a variety of interested stakeholders, the
air agency should consider submitting a summary and response to the
comments received during the public plan review process to the EPA
along with the recertification statement and/or revised mitigation
plan. While we are requiring an air agency to submit any received
public comments to the EPA after the air agency initially develops a
mitigation plan, we are not requiring that the air agency summarize and
submit public comments for subsequent reviews and plan reassessments.
    If the historically documented or known seasonal exceptional events
continue to result in elevated pollutant concentrations above the
relevant NAAQS, thus showing that the combination of the existing SIP
and the existing mitigation plan does not effectively safeguard public
health, the air agency should consider whether to strengthen the
mitigation plan.
    In adopting these revisions, it is possible that all affected air
agencies may not need to prepare new plans. If an air agency has
developed and implemented a contingency plan under 40 CFR part 51,
subpart H, Prevention of Air Pollution Emergency Episodes, that meets
the requirements of 40 CFR 51.152, and that includes provisions for
events that could be considered ``exceptional events'' under the
provisions in 40 CFR 50.14, then the subpart H contingency plan would
likely satisfy the mitigation requirements. If the identified basic
elements are included and addressed, including the element for public
comment, then other types of existing mitigation or contingency plans
may satisfy the mitigation plan requirements. For example, if an area
has developed a natural events action plan or a high wind action plan
covering high wind dust events, this plan likely would satisfy
mitigation elements for high wind dust events. Smoke management
programs and/or forest management plans might also satisfy the
mitigation elements for prescribed fires and wildfires. Most air
agencies likely have sufficient, established processes that meet the
public notification and education element, and which can be easily
adapted or modified to meet the mitigation elements proposed in this
action.
3. Implementing Mitigation Plans
    The EPA is finalizing implementation provisions that provide for
the EPA's review and verification of the mitigation plans' inclusion of
the required elements and to ensure that the development of the
mitigation plan included a public comment process. We would not
formally review the substance of the plan in the sense of approving the
details of the specific measures and commitments in the plan. We will,
however, review each submitted plan and verify that it includes the
required elements. Within 60 days of receipt of such a plan, the EPA
plans to notify the submitting air agency that we have reviewed the
mitigation plan and verified that it contains the required elements.
Mitigation plans developed under 40 CFR 51.930 are not required to be
included in a SIP or to be otherwise federally-enforceable.
    Commenters asked that we allow air agencies 2 years from the date
that they become subject to any mitigation plan requirements to develop
their mitigation plan. We note that developing an effective mitigation
plan that includes the required elements may require input from and
coordination with numerous stakeholders, including, but not limited to,
air agencies, public health officials, local governments,
representatives serving potentially affected minority and low-income
populations, if applicable, and the media. Additionally, air agencies
must make the mitigation plan available for public comment, and respond
and revise the mitigation plan in response to those comments, as
appropriate. Upon consideration, we believe 2 years is a reasonable
amount of time to ensure that air agencies have adequate time to
prepare comprehensive mitigation plans that respond to the public
health threat presented by historically documented or known seasonal
events. Therefore, we are incorporating the commenters' suggestion into
this preamble and into the final regulatory language. Thus, air
agencies with historically documented or known seasonal exceptional
events that we are formally identifying in this action as being subject
to the requirements of this section will have 2 years from the
effective date of this action to submit a mitigation plan to their
applicable EPA Regional office. The EPA will process events of the type
and pollutant that are the subject of the mitigation plan that occur
during this 2-year period following the general provisions outlined in
40 CFR 50.14. During this interim period, the EPA's concurrence on
demonstrations will not be contingent upon the affected air agency's
submittal of a mitigation plan because air agencies should have
sufficient time to develop their newly required mitigation plans. It is
not reasonable to delay acting on demonstration submittals while air
agencies prepare these plans. However, for events of the type subject
to the mitigation plan requirement that occur after this 2-year window,
the EPA's action on demonstrations will be contingent on the submittal
of a mitigation plan that meets the requirements of this action. As the
EPA identifies other areas subject to the mitigation requirements in
this final rule, we provide such notice to the affected air agencies.
Notified air agencies will then have a 2-year period to develop a
mitigation plan. During this period of development, the EPA's
concurrence on demonstrations for events of the type and pollutant that
are

the subject of the mitigation plan will not be contingent upon the
affected air agency's submittal of a mitigation plan.
    All areas subject to these mitigation plan requirements can submit
the mitigation plan to the EPA in advance of an event, or submit a
mitigation plan along with an exceptional events demonstration. The EPA
expects that mitigation plans developed according to this section will
assist agencies in satisfying the not reasonably controllable or
preventable criterion discussed in Section IV.E.2 of this preamble.

C. Comments and Responses

    While the majority of commenters provided feedback indicating their
preference to retain the existing mitigation requirements in 40 CFR
51.930 without revision, several other commenters supported the
development of mitigation plans either for areas with ``historically
documented'' or ``known seasonal'' events or all events. Of those
commenters providing feedback on the EPA's review of mitigation plans,
many commenters supported the ``review'' versus ``approval'' option. As
previously noted, we have implemented the review option, which we
proposed as Option 1. We believe that Option 1 maximizes the
flexibility of the air agency while providing for the protection of
public health through the EPA's review to ensure inclusion of required
plan content and through the required public review process. Also
consistent with commenter feedback, we have identified required program
components, but have not specified the required content. Rather, it is
appropriate to allow air agencies to develop mechanisms that are
tailored to their unique situations and events.
    Also regarding specific recommendations on plan content, one
commenter did not support public notification for exceedances of an
annual standard. The EPA agrees with the commenter that public
notification is not necessary when the pollutant concentrations exceed
or violate a 3-month rolling average or an annual average as these
exceedances/violations reflect cumulative effects and in many cases the
cause of the exceedance or violation is long past. We have clarified
this point by adding regulatory language requiring public notification
for exceedances or anticipated exceedances of short-term NAAQS. We also
added regulatory text and a footnote in this preamble to define
``short-term'' as a NAAQS with an averaging time that is less than or
equal to 24-hours.

VI. Environmental Justice Considerations

    The Exceptional Events Rule provides the criteria by which state,
local and tribal air agencies identify air quality data they believe
have been influenced by exceptional events, which by statutory
definition are not reasonably controllable or preventable. Because it
is not reasonable to control or prevent these events, they can affect
all downwind populations including minority and low-income populations.
For this reason, in adding CAA section 319(b), Congress identified as a
guiding principle in developing regulations, ``the principle that
protection of public health is the highest priority.'' The Exceptional
Events Rule at 40 CFR 50.14 requires air agencies to seek public
comment on prepared exceptional events demonstrations prior to
submitting them to the reviewing EPA Regional office. The public can
also comment on rulemakings that include decisions related to the
exclusion of event-influenced data. The mitigation of exceptional
events language at 40 CFR 51.930 also requires that air agencies
provide public notification and education programs related to events.
    To protect all people and communities, notably minority and low-
income populations, air agencies should ensure that notifications and
education programs are communicated using the language (e.g., English
and Spanish) and media (e.g., radio and postings in local community
centers) best suited to the target audience(s). Furthermore, this
action requires states to develop mitigation plans for recurring event
types. Additionally, these revisions to the Exceptional Events Rule are
being made as part of a public notice-and-comment rulemaking effort,
which included a public hearing. These opportunities for public input
in the rulemaking process, and the resulting requirements regarding
public input and education ensure that all those residing, working,
attending school or otherwise present in areas affected by exceptional
events, regardless of minority and economic status, are protected.

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is a significant regulatory action that was submitted
to the Office of Management and Budget (OMB) for review because it
raises novel policy issues. Any changes made in response to OMB
recommendations have been documented in the docket.

B. Paperwork Reduction Act (PRA)

    This action does not impose any new information collection burden
under the PRA. OMB has previously approved the information collection
activities for ambient air monitoring data and other supporting
measurements reporting and recordkeeping activities associated with the
40 CFR part 58 Ambient Air Quality Surveillance rule and has assigned
OMB control number 2060-0084. The information being requested under
these proposed rule revisions is consistent with current requirements
related to information needed to verify the authenticity of monitoring
data submitted to the EPA's AQS database, and to justify exclusion of
data that have been flagged as being affected by exceptional events.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. Instead, the
rule revisions provide the criteria and increase the efficiency of the
process by which state, local and tribal air agencies identify air
quality data they believe have been influenced by an exceptional event.
The rule revisions also clarify those actions that state, local and
tribal air agencies should take to protect public health during and
following an exceptional event. Because affected air agencies would
have discretion to implement controls on sources that may need to be
regulated due to anthropogenic contribution in the area determined to
be influenced by an exceptional event, the EPA cannot predict the
indirect effect of the rule on sources that may be small entities.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or
more as described in UMRA, 2 U.S.C. 1531-1538, and does not
significantly or uniquely affect small governments. The action imposes
no enforceable duty on any state, local or tribal governments or the
private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. The EPA
believes, however, that this action may be of significant interest to
states and to local air quality agencies to whom a state has delegated
relevant responsibilities for air quality management. Consistent with

the EPA's policy to promote communications between the EPA and state
and local governments, the EPA consulted with representatives of state
and local governments early in the process of developing this action to
permit them to have meaningful and timely input into its development. A
summary of the concerns raised during that consultation is provided in
Section IV of this preamble.

F. Executive Order 13175: Consultation and Coordination with Indian
Tribal Governments

    This action does not have tribal implications as specified in
Executive Order 13175. It would not have a substantial direct effect on
one or more Indian tribes. Furthermore, these regulation revisions do
not affect the relationship or distribution of power and
responsibilities between the federal government and Indian tribes. The
CAA and the TAR establish the relationship of the federal government
and tribes in characterizing air quality and developing plans to attain
the NAAQS, and these revisions to the regulations do nothing to modify
that relationship. Thus, Executive Order 13175 does not apply to this
action.
    Although Executive Order 13175 does not apply to this action, the
EPA held public meetings attended by tribal representatives and
separate meetings with tribal representatives to discuss the revisions
proposed in this action. The EPA also provided an opportunity for all
interested parties to provide oral or written comments on potential
concepts for the EPA to address during the rule revision process.
Summaries of these meetings are included in the docket for this rule.
The EPA received comments on this action from multiple tribal
organizations, requesting clarification on how this action includes and
protects federal tribal communities. The Exceptional Events Rule
addresses these concerns through the public comment process for both
the rule revision and the exceptional events demonstrations, outreach
efforts, and notification requirements.

G. Executive Order 13045: Protection of Children From Environmental
Health & Safety Risks

    The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive Order. This action is not subject to
Executive Order 13045 because it does not concern an environmental
health risk or safety risk.

H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use

    This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution or use of energy. The purpose of this proposed rule is to
provide the criteria, and increase the efficiency of the process, by
which state, local and tribal air agencies may identify air quality
data they believe have been influenced by an exceptional event. The EPA
does not expect these activities to affect energy suppliers,
distributors or users.

I. National Technology Transfer and Advancement Act

    This rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    The EPA believes that this action does not have disproportionately
high and adverse human health or environmental effects on minority
populations, low-income populations and/or indigenous peoples, as
specified in Executive Order 12898 (59 FR 7629, February 16, 1994). The
documentation for this decision is contained in the Section VI of the
preamble titled ``Environmental Justice Considerations.'' This action
provides the criteria and increases the efficiency of the process by
which state, local and tribal air agencies identify air quality data
they believe have been influenced by exceptional events, which, by
statutory definition, are not reasonably controllable or preventable.
These regulatory provisions do, however, provide information concerning
actions that state, local or tribal air agencies might take to
uniformly protect public health once the EPA has concurred with an air
agency's request to exclude data influenced by an exceptional event.
The mitigation component of the rule could ultimately provide
additional protection for minority, low income and other populations
located in areas affected by recurring exceptional events. Therefore,
the EPA finds that this action would not adversely affect the health or
safety of minority or low-income populations, and that it is designed
to protect and enhance the health and safety of these and other
populations.

K. Congressional Review Act (CRA)

    This action is subject to the CRA, and the EPA will submit a rule
report to each House of the Congress and to the Comptroller General of
the United States. This action is not a ``major rule'' as defined by 5
U.S.C. 804(2).
Page 225 of 247--Treatment of Data Influenced by Exceptional Events

VIII. Statutory Authority

    The statutory authority for this action is provided by 42 U.S.C.
7401, et seq.

List of Subjects

40 CFR Part 50

    Environmental protection, Air pollution control, National parks,
Wilderness areas.

40 CFR Part 51

    Environmental protection, Air pollution control, National parks,
Wilderness areas.

    Dated: September 16, 2016.
Gina McCarthy,
Administrator.

    For the reasons set forth in the preamble, parts 50 and 51, title
40, chapter I of the Code of Federal Regulations are amended as
follows:

PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY
STANDARDS

0
1. The authority citation for part 50 continues to read as follows:

    Authority:  42 U.S.C. 7401, et seq.

0
2. Amend Sec.  50.1 by:
0
a. Revising paragraphs (j) and (k).
0
b. Adding paragraphs (m), (n), (o), (p), (q) and (r).
    The revisions and additions read as follows:

Sec.  50.1  Definitions.

* * * * *
    (j) Exceptional event means an event(s) and its resulting emissions
that affect air quality in such a way that there exists a clear causal
relationship between the specific event(s) and the monitored
exceedance(s) or violation(s), is not reasonably controllable or
preventable, is an event(s) caused by human activity that is unlikely
to recur at a particular location or a natural event(s), and is
determined by the Administrator in accordance with 40 CFR 50.14 to be
an exceptional event. It does not include air pollution relating to
source noncompliance. Stagnation of air masses and meteorological
inversions do not directly cause pollutant emissions and are not
exceptional events. Meteorological events involving

high temperatures or lack of precipitation (i.e., severe, extreme or
exceptional drought) also do not directly cause pollutant emissions and
are not considered exceptional events. However, conditions involving
high temperatures or lack of precipitation may promote occurrences of
particular types of exceptional events, such as wildfires or high wind
events, which do directly cause emissions.
    (k) Natural event means an event and its resulting emissions, which
may recur at the same location, in which human activity plays little or
no direct causal role. For purposes of the definition of a natural
event, anthropogenic sources that are reasonably controlled shall be
considered to not play a direct role in causing emissions.
* * * * *
    (m) Prescribed fire is any fire intentionally ignited by management
actions in accordance with applicable laws, policies, and regulations
to meet specific land or resource management objectives.
    (n) Wildfire is any fire started by an unplanned ignition caused by
lightning; volcanoes; other acts of nature; unauthorized activity; or
accidental, human-caused actions, or a prescribed fire that has
developed into a wildfire. A wildfire that predominantly occurs on
wildland is a natural event.
    (o) Wildland means an area in which human activity and development
are essentially non-existent, except for roads, railroads, power lines,
and similar transportation facilities. Structures, if any, are widely
scattered.
    (p) High wind dust event is an event that includes the high-speed
wind and the dust that the wind entrains and transports to a monitoring
site.
    (q) High wind threshold is the minimum wind speed capable of
causing particulate matter emissions from natural undisturbed lands in
the area affected by a high wind dust event.
    (r) Federal land manager means, consistent with the definition in
40 CFR 51.301, the Secretary of the department with authority over the
Federal Class I area (or the Secretary's designee) or, with respect to
Roosevelt-Campobello International Park, the Chairman of the Roosevelt-
Campobello International Park Commission.

0
3. Revise Sec.  50.14 to read as follows:

Sec.  50.14  Treatment of air quality monitoring data influenced by
exceptional events.

    (a) Requirements--(1) Scope. (i) This section applies to the
treatment of data showing exceedances or violations of any national
ambient air quality standard for purposes of the following types of
regulatory determinations by the Administrator:
    (A) An action to designate an area, pursuant to Clean Air Act
section 107(d)(1), or redesignate an area, pursuant to Clean Air Act
section 107(d)(3), for a particular national ambient air quality
standard;
    (B) The assignment or re-assignment of a classification category to
a nonattainment area where such classification is based on a comparison
of pollutant design values, calculated according to the specific data
handling procedures in 40 CFR part 50 for each national ambient air
quality standard, to the level of the relevant national ambient air
quality standard;
    (C) A determination regarding whether a nonattainment area has
attained the level of the appropriate national ambient air quality
standard by its specified deadline;
    (D) A determination that an area has data for the specific NAAQS,
which qualify the area for an attainment date extension under the CAA
provisions for the applicable pollutant;
    (E) A determination under Clean Air Act section 110(k)(5), if based
on an area violating a national ambient air quality standard, that the
state implementation plan is inadequate under the requirements of Clean
Air Act section 110; and
    (F) Other actions on a case-by-case basis as determined by the
Administrator.
    (ii) A State, federal land manager or other federal agency may
request the Administrator to exclude data showing exceedances or
violations of any national ambient air quality standard that are
directly due to an exceptional event from use in determinations
identified in paragraph (a)(1)(i) of this section by demonstrating to
the Administrator's satisfaction that such event caused a specific air
pollution concentration at a particular air quality monitoring
location.
    (A) For a federal land manager or other federal agency to be
eligible to initiate such a request for data exclusion, the federal
land manager or other federal agency must:
    (1) Either operate a regulatory monitor that has been affected by
an exceptional event or manage land on which an exceptional event
occurred that influenced a monitored concentration at a regulatory
monitor; and
    (2) Initiate such a request only after the State in which the
affected monitor is located concurs with the federal land manager's or
other federal agency's submittal.
    (B) With regard to such a request, all provisions in this section
that are expressed as requirements applying to a State shall, except as
noted, be requirements applying to the federal land manager or other
federal agency.
    (C) Provided all provisions in this section are met, the
Administrator shall allow a State to submit demonstrations for any
regulatory monitor within its jurisdictional bounds, including those
operated by federal land managers, other federal agencies and delegated
local agencies.
    (D) Where multiple agencies within a state submit demonstrations
for events that meet the requirements of the Exceptional Events Rule, a
State submittal shall have primacy for any regulatory monitor within
its jurisdictional bounds.
    (2) A demonstration to justify data exclusion may include any
reliable and accurate data, but must specifically address the elements
in paragraphs (c)(3)(iv) and (v) of this section.
    (b) Determinations by the Administrator--(1) Generally. The
Administrator shall exclude data from use in determinations of
exceedances and violations identified in paragraph (a)(1)(i) of this
section where a State demonstrates to the Administrator's satisfaction
that an exceptional event caused a specific air pollution concentration
at a particular air quality monitoring location and otherwise satisfies
the requirements of this section.
    (2) Fireworks displays. The Administrator shall exclude data from
use in determinations of exceedances and violations where a State
demonstrates to the Administrator's satisfaction that emissions from
fireworks displays caused a specific air pollution concentration in
excess of one or more national ambient air quality standards at a
particular air quality monitoring location and otherwise satisfies the
requirements of this section. Such data will be treated in the same
manner as exceptional events under this rule, provided a State
demonstrates that such use of fireworks is significantly integral to
traditional national, ethnic, or other cultural events including, but
not limited to, July Fourth celebrations that satisfy the requirements
of this section.
    (3) Prescribed fires. (i) The Administrator shall exclude data from
use in determinations of exceedances and violations, where a State
demonstrates to the Administrator's satisfaction that emissions from
prescribed fires caused a specific air pollution concentration in
excess of one or more national ambient air quality standards at a
particular air quality monitoring location and otherwise

satisfies the requirements of this section.
    (ii) In addressing the requirements set forth in paragraph
(c)(3)(iv)(D) of this section regarding the not reasonably controllable
or preventable criterion:
    (A) With respect to the requirement that a prescribed fire be not
reasonably controllable, the State must either certify to the
Administrator that it has adopted and is implementing a smoke
management program or the State must demonstrate that the burn manager
employed appropriate basic smoke management practices identified in
Table 1 to Sec.  50.14. Where a burn manager employs appropriate basic
smoke management practices, the State may rely on a statement or other
documentation provided by the burn manager that he or she employed
those practices. If an exceedance or violation of a NAAQS occurs when a
prescribed fire is employing an appropriate basic smoke management
practices approach, the State and the burn manager must undertake a
review of the subject fire, including a review of the basic smoke
management practices applied during the subject fire to ensure the
protection of air quality and public health and progress towards
restoring and/or maintaining a sustainable and resilient wildland
ecosystem. If the prescribed fire becomes the subject of an exceptional
events demonstration, documentation of the post-burn review must
accompany the demonstration.
    (B) If the State anticipates satisfying the requirements of
paragraph (c)(3)(iv)(D) of this section by employing the appropriate
basic smoke management practices identified in Table 1 to Sec.  50.14,
then:
    (1) The State, federal land managers, and other entities as
appropriate, must periodically collaborate with burn managers operating
within the jurisdiction of the State to discuss and document the
process by which air agencies and land managers will work together to
protect public health and manage air quality impacts during the conduct
of prescribed fires on wildland. Such discussions must include outreach
and education regarding general expectations for the selection and
application of appropriate basic smoke management practices and goals
for advancing strategies and increasing adoption and communication of
the benefits of appropriate basic smoke management practices;
    (2) The State, federal land managers and burn managers shall have
an initial implementation period, defined as being 2 years from
September 30, 2016, to implement the collaboration and outreach effort
identified in paragraph (b)(3)(ii)(B)(1) of this section; and
    (3) Except as provided in paragraph (b)(3)(ii)(B)(2) of this
section, the Administrator shall not place a concurrence flag in the
appropriate field for the data record in the AQS database, as specified
in paragraph (c)(2)(ii) of this section, if the data are associated
with a prescribed fire on wildland unless the requirements of paragraph
(b)(3)(ii)(B)(1) of this section have been met and associated
documentation accompanies any applicable exceptional events
demonstration. The Administrator may nonconcur or defer action on such
a demonstration.
    (C) With respect to the requirement that a prescribed fire be not
reasonably preventable, the State may rely upon and reference a multi-
year land or resource management plan for a wildland area with a stated
objective to establish, restore and/or maintain a sustainable and
resilient wildland ecosystem and/or to preserve endangered or
threatened species through a program of prescribed fire provided that
the Administrator determines that there is no compelling evidence to
the contrary in the record and the use of prescribed fire in the area
has not exceeded the frequency indicated in that plan.
    (iii) Provided the Administrator determines that there is no
compelling evidence to the contrary in the record, in addressing the
requirements set forth in paragraph (c)(3)(iv)(E) of this section
regarding the human activity unlikely to recur at a particular location
criterion for demonstrations involving prescribed fires on wildland,
the State must describe the actual frequency with which a burn was
conducted, but may rely upon and reference an assessment of the natural
fire return interval or the prescribed fire frequency needed to
establish, restore and/or maintain a sustainable and resilient wildland
ecosystem contained in a multi-year land or resource management plan
with a stated objective to establish, restore and/or maintain a
sustainable and resilient wildland ecosystem and/or to preserve
endangered or threatened species through a program of prescribed fire.

  Table 1 to Sec.   50.14--Summary of Basic Smoke Management Practices,
         Benefit Achieved With the BSMP, and When it is Applieda
------------------------------------------------------------------------
                                                        When the BSMP is
    Basic Smoke Management      Benefit achieved with   applied--before/
         Practice \b\                  the BSMP         during/after the
                                                              burn
------------------------------------------------------------------------
Evaluate Smoke Dispersion       Minimize smoke         Before, During,
 Conditions.                     impacts.               After.
Monitor Effects on Air Quality  Be aware of where the  Before, During,
                                 smoke is going and     After.
                                 degree it impacts
                                 air quality.
Record-Keeping/Maintain a Burn/ Retain information     Before, During,
 Smoke Journal.                  about the weather,     After.
                                 burn and smoke. If
                                 air quality problems
                                 occur, documentation
                                 helps analyze and
                                 address air
                                 regulatory issues..
Communication--Public           Notify neighbors and   Before, During.
 Notification.                   those potentially
                                 impacted by smoke,
                                 especially sensitive
                                 receptors.
Consider Emission Reduction     Reducing emissions     Before, During,
 Techniques.                     through mechanisms     After.
                                 such as reducing
                                 fuel loading can
                                 reduce downwind
                                 impacts.
Share the Airshed--             Coordinate multiple    Before, During,
 Coordination of Area Burning.   burns in the area to   After.
                                 manage exposure of
                                 the public to smoke.
------------------------------------------------------------------------
\a\ The EPA believes that elements of these BSMP could also be practical
  and beneficial to apply to wildfires for areas likely to experience
  recurring wildfires.
\b\ The listing of BSMP in this table is not intended to be all-
  inclusive. Not all BSMP are appropriate for all burns. Goals for
  applicability should retain flexibility to allow for onsite variation
  and site-specific conditions that can be variable on the day of the
  burn. Burn managers can consider other appropriate BSMP as they become
  available due to technological advancement or programmatic refinement.

    (4) Wildfires. The Administrator shall exclude data from use in
determinations of exceedances and violations where a State demonstrates
to the Administrator's satisfaction that emissions from wildfires
caused a

specific air pollution concentration in excess of one or more national
ambient air quality standard at a particular air quality monitoring
location and otherwise satisfies the requirements of this section.
Provided the Administrator determines that there is no compelling
evidence to the contrary in the record, the Administrator will
determine every wildfire occurring predominantly on wildland to have
met the requirements identified in paragraph (c)(3)(iv)(D) of this
section regarding the not reasonably controllable or preventable
criterion.
    (5) High wind dust events. (i) The Administrator shall exclude data
from use in determinations of exceedances and violations, where a State
demonstrates to the Administrator's satisfaction that emissions from a
high wind dust event caused a specific air pollution concentration in
excess of one or more national ambient air quality standards at a
particular air quality monitoring location and otherwise satisfies the
requirements of this section provided that such emissions are from high
wind dust events.
    (ii) The Administrator will consider high wind dust events to be
natural events in cases where windblown dust is entirely from natural
undisturbed lands in the area or where all anthropogenic sources are
reasonably controlled as determined in accordance with paragraph (b)(8)
of this section.
    (iii) The Administrator will accept a high wind threshold of a
sustained wind of 25 mph for areas in the States of Arizona,
California, Colorado, Kansas, Nebraska, Nevada, New Mexico, North
Dakota, Oklahoma, South Dakota, Texas, Utah, and Wyoming provided this
value is not contradicted by evidence in the record at the time the
State submits a demonstration. In lieu of this threshold, States can
identify and use an Administrator-approved alternate area-specific high
wind threshold that is more representative of local or regional
conditions, if appropriate.
    (iv) In addressing the requirements set forth in paragraph
(c)(3)(iv)(D) of this section regarding the not reasonably preventable
criterion, the State shall not be required to provide a case-specific
justification for a high wind dust event.
    (v) With respect to the not reasonably controllable criterion of
paragraph (c)(3)(iv)(D) of this section, dust controls on an
anthropogenic source shall be considered reasonable in any case in
which the controls render the anthropogenic source as resistant to high
winds as natural undisturbed lands in the area affected by the high
wind dust event. The Administrator may determine lesser controls
reasonable on a case-by-case basis.
    (vi) For large-scale and high-energy high wind dust events, the
Administrator will generally consider a demonstration documenting the
nature and extent of the event to be sufficient with respect to the not
reasonably controllable criterion of paragraph (c)(3)(iv)(D) of this
section provided the State provides evidence showing that the event
satisfies the following:
    (A) The event is associated with a dust storm and is the focus of a
Dust Storm Warning.
    (B) The event has sustained winds that are greater than or equal to
40 miles per hour.
    (C) The event has reduced visibility equal to or less than 0.5
miles.
    (6) Stratospheric Intrusions. Where a State demonstrates to the
Administrator's satisfaction that emissions from stratospheric
intrusions caused a specific air pollution concentration in excess of
one or more national ambient air quality standard at a particular air
quality monitoring location and otherwise satisfies the requirements of
this section, the Administrator will determine stratospheric intrusions
to have met the requirements identified in paragraph (c)(3)(iv)(D) of
this section regarding the not reasonably controllable or preventable
criterion and shall exclude data from use in determinations of
exceedances and violations.
    (7) Determinations with respect to event aggregation, multiple
national ambient air quality standards for the same pollutant, and
exclusion of 24-hour values for particulate matter.
    (i) Where a State demonstrates to the Administrator's satisfaction
that for national ambient air quality standards with averaging or
cumulative periods less than or equal to 24 hours the aggregate effect
of events occurring on the same day has caused an exceedance or
violation, the Administrator shall determine such collective data to
satisfy the requirements in paragraph (c)(3)(iv)(B) of this section
regarding the clear causal relationship criterion. Where a State
demonstrates to the Administrator's satisfaction that for national
ambient air quality standards with averaging or cumulative periods
longer than 24 hours the aggregate effect of events occurring on
different days has caused an exceedance or violation, the Administrator
shall determine such collective data to satisfy the requirements in
paragraph (c)(3)(iv)(B) of this section regarding the clear causal
relationship criterion.
    (ii) The Administrator shall accept as part of a demonstration for
the clear causal relationship in paragraph (c)(3)(iv)(B) of this
section with respect to a 24-hour NAAQS, a State's comparison of a 24-
hour concentration of any national ambient air quality standard
pollutant to the level of a national ambient air quality standard for
the same pollutant with a longer averaging period. The Administrator
shall also accept as part of a demonstration for the clear causal
relationship in paragraph (c)(3)(iv)(B) of this section with respect to
a NAAQS with a longer averaging period, a State's comparison of a 24-
hour concentration of any national ambient air quality standard
pollutant to the level of the national ambient air quality standard for
the same pollutant with a longer averaging period, without the State
having to demonstrate that the event caused the annual average
concentration of the pollutant to exceed the level of the NAAQS with
the longer averaging period.
    (iii) Where a State operates a continuous analyzer that has been
designated as a Federal Equivalent Method monitor as defined in 40 CFR
50.1(g) that complies with the monitoring requirements of 40 CFR part
58, Appendix C, and the State believes that collected data have been
influenced by an event, in following the process outlined in paragraph
(c)(2) of this section, the State shall create an initial event
description and flag the associated event-influenced data that have
been submitted to the AQS database for the affected monitor. Where a
State demonstrates to the Administrator's satisfaction that such data
satisfy the requirements in paragraph (c)(3)(iv)(B) of this section
regarding the clear causal relationship criterion and otherwise satisfy
the requirements of this section, the Administrator shall agree to
exclude all data within the affected calendar day(s).
    (8) Determinations with respect to the not reasonably controllable
or preventable criterion. (i) The not reasonably controllable or
preventable criterion has two prongs that the State must demonstrate:
prevention and control.
    (ii) The Administrator shall determine that an event is not
reasonably preventable if the State shows that reasonable measures to
prevent the event were applied at the time of the event.
    (iii) The Administrator shall determine that an event is not
reasonably controllable if the State shows that reasonable measures to
control the impact of the event on air quality were applied at the time
of the event.
    (iv) The Administrator shall assess the reasonableness of available
controls for

anthropogenic sources based on information available as of the date of
the event.
    (v) Except where a State, tribal or federal air agency is obligated
to revise its state implementation plan, tribal implementation plan, or
federal implementation plan, the Administrator shall consider
enforceable control measures implemented in accordance with a state
implementation plan, tribal implementation plan, or federal
implementation plan, approved by the EPA within 5 years of the date of
the event, that address the event-related pollutant and all sources
necessary to fulfill the requirements of the Clean Air Act for the
state implementation plan, tribal implementation plan, or federal
implementation plan to be reasonable controls with respect to all
anthropogenic sources that have or may have contributed to the
monitored exceedance or violation.
    (vi) Where a State, tribal or federal air agency is obligated to
revise its state implementation plan, tribal implementation plan, or
federal implementation plan, the deference to enforceable control
measures identified in paragraph (b)(8)(v) of this section shall remain
only until the due date of the required state implementation plan,
tribal implementation plan, or federal implementation plan revisions.
However, where an air agency is obligated to revise the enforceable
control measures identified in paragraph (b)(8)(v) of this section in
its implementation plan as a result of an action pursuant to Clean Air
Act section 110(k)(5), the deference, if any, to those enforceable
control measures shall be determined on a case-by-case basis.
    (vii) The Administrator shall not require a State to provide case-
specific justification to support the not reasonably controllable or
preventable criterion for emissions-generating activity that occurs
outside of the State's jurisdictional boundaries within which the
concentration at issue was monitored. In the case of a tribe treated as
a state under 40 CFR 49.2 with respect to exceptional events
requirements, the tribe's jurisdictional boundaries for purposes of
requiring or directly implementing emission controls apply. In the case
of a federal land manager or other federal agency submitting a
demonstration under the requirements of this section, the
jurisdictional boundaries that apply are those of the State or the
tribe depending on which has jurisdiction over the area where the event