 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued September 11, 2018          Decided October 19, 2018

                        No. 16-1314

                  SAMUEL MASIAS, ET AL.,
                      PETITIONERS

                             v.

    ENVIRONMENTAL PROTECTION AGENCY AND ANDREW
    WHEELER, ACTING ADMINISTRATOR, UNITED STATES
         ENVIRONMENTAL PROTECTION AGENCY,
                    RESPONDENTS

 UNION ELECTRIC COMPANY AND UTILITY AIR REGULATORY
                       GROUP,
                    INTERVENORS


            Consolidated with 16-1318, 16-1384


        On Petitions for Review of an Action of the
       United States Environmental Protection Agency


     Robert Ukeiley argued the cause and filed the briefs for
petitioners Samuel Masias, et al.
                               2

    Lisa K. Perfetto argued the cause for petitioner Sierra
Club. With her on the briefs were Thomas J. Cmar and Joshua
D. Smith.

     Dennis Lane argued the cause and filed the briefs for
petitioner Kansas City Board of Public Utilities.

     Amanda Shafer Berman, Attorney, U.S. Department of
Justice, argued the cause for respondents. With her on the brief
was Jonathan D. Brightbill, Deputy Assistant Attorney
General. John C. Cruden entered an appearance.

    Lucinda Minton Langworthy argued the cause for
respondent-intervenors. With her on the brief were Renee
Cipriano, J. Michael Showalter, and Aaron M. Flynn.

   Before: TATEL and MILLETT, Circuit Judges, and
WILLIAMS, Senior Circuit Judge.

   Opinion for the Court filed by Senior Circuit Judge
WILLIAMS.

     WILLIAMS, Senior Circuit Judge: This case arises out of
the Environmental Protection Agency’s designation of 61 areas
under the National Ambient Air Quality Standard for sulfur
dioxide.      In these consolidated cases, industry and
environmental petitioners challenge EPA’s determination that
it could not, on the basis of “available information,” classify
three of the 61 areas as meeting or not meeting the air quality
standard, and that it must therefore designate them as
“unclassifiable.” For the reasons below, we dismiss or deny the
petitions for review.
                                3

                              * * *

      The Clean Air Act, 42 U.S.C. §§ 7401–7671q, directs EPA
to set the maximum permissible concentration of certain
pollutants in the ambient air. These standards are called
National Ambient Air Quality Standards, or NAAQS. Id.
§§ 7408–7409. Once EPA promulgates a new NAAQS for a
given pollutant, states are to submit lists designating all areas
in the state as being in “attainment,” in “nonattainment,” or
“unclassifiable” with respect to that standard.                Id.
§ 7407(d)(1)(A). “Nonattainment” areas are ones that violate
the NAAQS or contribute to NAAQS violations in a nearby
area; “attainment” areas meet the NAAQS; and
“unclassifiable” areas are those which cannot be classified on
the basis of “available information.” Id. § 7407(d)(1)(A)(i)–
(iii). EPA itself either promulgates the states’ designations or
modifies them as appropriate; the agency also makes its own
designations when a state fails to do so. Id. § 7407(d)(1)(B)(i)–
(ii). (EPA uses its own label—“unclassifiable/attainment”—
for areas that are “attainment” or “likely attainment.” 81 Fed.
Reg. 45,039, 45,041/3 n.3 (July 12, 2016). But as there is no
practical     difference      between       “attainment”      and
“unclassifiable/attainment,”      we      use     the    simpler,
congressionally created category throughout this opinion.)

     Issuance of a new NAAQS also triggers a state duty to
adopt plans for implementing, maintaining, and enforcing that
air quality standard. Id. § 7410(a). These state implementation
plans, or SIPs, provide a blueprint for imposing controls on
pollution sources. Id. §§ 7502(c), 7503(a). For areas that EPA
designates as “attainment” or “unclassifiable,” SIPs must
“prevent significant deterioration of air quality.” Id. § 7471.
For areas that EPA designates as “nonattainment,” SIPs must
go further, and strive for attainment of the air quality standard
“as expeditiously as practicable . . . .” Id. § 7502(a)(2)(A), (c).
                               4

     On June 22, 2010, EPA issued a new standard for sulfur
dioxide, or SO2. 75 Fed. Reg. 35,520 (June 22, 2010). The
new SO2 NAAQS imposed a ceiling of 75 parts per billion,
based on the three-year average of the annual 99th percentile of
1-hour daily maximum concentrations. Id. at 35,520/1. Having
issued one round of area designations in 2013, EPA issued a
second round in 2016, designating 61 areas in 24 states. 81
Fed. Reg. at 45,040/3.

     Each of the three petitioners now before us challenges one
of those 61 designations. Petitioner Kansas City Board of
Public Utilities challenges EPA’s designation of Wyandotte
County, Kansas; petitioner Sierra Club objects to EPA’s
designation of Gallia County, Ohio; and petitioners Samuel
Masias et al. take issue with EPA’s designation of Colorado
Springs, Colorado. (The areas at issue do not map exactly onto
the legally designated boundaries of the political entities, see
id. at 45,046, 45,049, 45,053, but we use the simplifying labels
applied by the parties.)

     In reviewing these challenges, “we apply the same
standard of review . . . as we do under the Administrative
Procedure Act,” Nat’l Envtl. Dev. Association’s Clean Air
Project v. EPA, 891 F.3d 1041, 1047 (D.C. Cir. 2018) (quoting
Allied Local & Regional Mfrs. Caucus v. EPA, 215 F.3d 61, 68
(D.C. Cir. 2000)), “and we will affirm EPA’s action ‘if the
record shows EPA considered all relevant factors and
articulated a rational connection between the facts found and
the choice made,’” Nat’l Biodiesel Bd. v. EPA, 843 F.3d 1010,
1018 (D.C. Cir. 2016) (internal quotation marks omitted)
(quoting Catawba Cnty. v. EPA, 571 F.3d 20, 41 (D.C. Cir.
2009)).

     For the reasons below, we dismiss the Board’s petition for
lack of standing and deny Sierra Club’s and Masias’s petitions
                               5

on the merits. We take the Board’s petition first, then those of
Sierra Club and Masias.


                             * * *

    For a power plant operator, the Board’s claim is unusual.
We typically hear that EPA improperly designated an area as
“nonattainment” and thus subjected a regulated party to costly
(or more costly) pollution controls. In such cases, standing is
“clear” and usually “uncontested.” See, e.g., Treasure State
Res. Indus. Ass’n v. EPA, 805 F.3d 300, 303 (D.C. Cir. 2015).

     Not so here. Because EPA designated Wyandotte County
as “unclassifiable,” the Board does not—and cannot—claim
that it was subjected to regulatory burdens beyond those
applicable under the Board’s preferred designation—
“attainment.” The statute requires that SIPs for areas
designated attainment or unclassifiable alike include measures
to “prevent significant deterioration of air quality.” 42 U.S.C.
§ 7471. That’s all. Thus the statutory burdens (and the
regulatory ones, see, e.g., 40 C.F.R. § 52.21(a)(2)(i)) are the
same, and the Board cannot point to a heavier regulatory burden
resulting from EPA’s failure to make what the Board claims is
the legally correct choice. Catawba Cnty. v. EPA, No. 05-1064,
slip op. at 2 (D.C. Cir. July 7, 2009) (unpublished); see also,
e.g., Miss. Comm’n on Envtl. Quality v. EPA, 790 F.3d 138,
145 (D.C. Cir. 2015); BP Cherry Point, 12 E.A.D. 209, 230
n.51 (EAB 2005). In these circumstances, the Board appears
to meet no part of the familiar threefold standing requirement—
that it has suffered a concrete and particularized injury that is
fairly traceable to the challenged conduct, and is likely to be
redressed by a favorable decision. See Lujan v. Defenders of
Wildlife, 504 U.S. 555, 560–61 (1992); Nat’l Ass’n of Home
Builders v. EPA, 667 F.3d 6, 14 (D.C. Cir. 2011).
                                6

     Given the lack of any difference in the legal obligations
flowing from either designation, the Board argues that the
“unclassifiable” designation subjects it to more “uncertainty”
as to whether Wyandotte County was actually in attainment at
the time of EPA’s designation than an attainment designation
would have. Board’s Br. 17. That matters, the Board says,
because it signals a difference in the risk of redesignation to
nonattainment and all the associated burdens. An “attainment”
designation, it believes, would “offer[] a high level of certainty
that Wyandotte County had already achieved NAAQS
compliance,” and “thus minimiz[e] the threat” that EPA would
later redesignate the area as nonattainment. Board’s Reply Br.
at 7–8; see also Oral Argument at 24:40.

     But the Board offers neither evidence nor reason to believe
that an “attainment” designation would impact EPA’s future
actions or in any way make a “nonattainment” redesignation
less likely or less imminent. By statute EPA can “at any time”
redesignate the area, 42 U.S.C. § 7407(d)(3)(A) (emphasis
added); even without new information, EPA can change course
with nothing more than a “reasoned explanation,” see, e.g., U.S.
Sugar Corp. v. EPA, 830 F.3d 579, 626 (D.C. Cir. 2016); Nat’l
Ass’n of Home Builders v. EPA, 682 F.3d 1032, 1037–38 (D.C.
Cir. 2012); Arkema, Inc. v. EPA, 618 F.3d 1, 6 (D.C. Cir. 2010).
See Oral Argument at 20:15 (Court: “But it is the case that . . .
in either of these categories, the EPA is free at any time, on its
own motion, to re-examine . . . the classification?” Board
Counsel: “Absolutely, Your Honor.”).

     Even though EPA has the same statutory authority to
redesignate both “unclassifiable” and “attainment” areas (“at
any time”), it might be the case that as a practical matter EPA
redesignates “unclassifiable” areas at a higher rate. If that were
true, perhaps the Board could rest standing on a “substantially
increased” risk of imminent “regulation or enforcement.” Nat’l
Ass’n of Home Builders, 667 F.3d at 14. The Board, however,
                               7

offers no facts to support such a claim. Elec. Privacy Info. Ctr.
v. Presidential Advisory Comm’n on Election Integrity, 878
F.3d 371, 379 (D.C. Cir. 2017) (citing Lujan, 504 U.S. at 561);
see Oral Argument at 26:04 (Court: “[A]re there any empirical
data on the frequency of EPA moves to change on the one hand
an unclassifiable designation and on the other hand an
[unclassifiable / attainment designation]?” Board Counsel: “If
there are, I don’t know.”).

    In a similar vein the Board suggests that the State of
Kansas would “most likely” respond to the “unclassifiable”
designation by imposing “new controls” in Wyandotte County.
Board’s Reply Br. 6. Why so? The Board offers no more
support for this prediction than it did for the likelihood of EPA
redesignation. This is not one of those cases where a federal
determination “alters the legal regime” in such a way as to
create a significant likelihood of a state action adverse to the
complaining party’s interests. Cf. Nat’l Parks Conservation
Ass’n v. Manson, 414 F.3d 1, 6–7 (D.C. Cir. 2005) (quoting
Bennett v. Spear, 520 U.S. 154, 169 (1997)).

     Finally, the Board expresses concern that finding no
standing here would eliminate all review because EPA
“always” has authority to redesignate “any area under any
designation.” Board’s Reply Br. 8–9. This is, unfortunately
for petitioner, nonsense. Normally challengers of a designation
rest their standing on the way in which its regulatory
consequences harm them in comparison with a designation they
claim to be legally or factually required—typically industry
challenging nonattainment designations and environmentalists
challenging attainment designations or (as in the two remaining
cases here) unclassifiable ones.        Agency authority to
redesignate couldn’t undermine that standing—unless it were
so common as to render designations non-final. Apart from
that, the assumption that if the Board has “no standing to sue,
no one would have standing,” would, even if true, not be a
                               8

reason in itself to find standing. Clapper v. Amnesty Int’l USA,
568 U.S. 398, 420 (2013) (quoting Valley Forge Christian Coll.
v. Ams. United for Separation of Church & State, Inc., 454 U.S.
464, 489 (1982)).

     In short, the Board has not demonstrated that EPA’s
“unclassifiable” designation, compared to the “attainment”
designation the Board claims to have been required, has
subjected it to any cognizable injury. We dismiss the Board’s
petition.


                            * * *

     We turn now to the Ohio designation. The sequence of
events greatly complicates the issues. In the course of 2015
EPA received conflicting air dispersion modeling from both
Sierra Club and the Ohio Environmental Protection Agency
(“Ohio”), the former showing Gallia County in nonattainment,
the latter showing it in attainment. See Final Technical Support
Document for Final Action on Ohio Area Designations at 19–
20, EPA-HQ-OAR-2014-0464-0405, J.A. 613–14; Technical
Support Document: Ohio Area Designations at 28–29, EPA-
HQ-OAR-2014-0464-0134, J.A. 228–29. EPA rejected both
modeling sets as unreliable, a decision Sierra Club doesn’t
contest.

     Pursuant to a March 1, 2016 order of EPA, the time for
public comment on all the Round 2 designations closed March
31, 2016. See 81 Fed. Reg. 10,563, 10,564/1 (Mar. 1, 2016).
Thereafter (in April 2016 but not barred by the close of public
comments), Ohio submitted new modeling. In its final decision
EPA rejected this modeling, solely (in Sierra Club’s view, see
Br. 19) on the ground that it had inappropriately reduced an
input—SO2 background concentrations—by 38%. As both the
final Ohio submission and EPA’s rejection occurred after the
                               9

close of comments, Sierra Club had no opportunity to respond
to either.

     Here Sierra Club claims that the Ohio modeling was
susceptible to a “basic mathematical fix,” namely restoring
pollution levels that Ohio’s inappropriate 38% reduction had
removed. This would have resolved EPA’s sole objection, says
Sierra Club, and conclusively demonstrated nonattainment.
See Sierra Club’s Br. 16–21.

     Perhaps so. But Sierra Club’s is an argument for the
agency, not this court—at least in the first instance. The Clean
Air Act expressly limits our review to “[o]nly” those objections
that were “raised with reasonable specificity during the period
for public comment.” 42 U.S.C. § 7607(d)(7)(B) (emphasis
added). Because Sierra Club’s objection here is based entirely
on modeling that EPA received after the period for public
comment and on EPA’s even later assessment of that modeling,
Sierra Club did not raise that objection during the comment
period—and could not possibly have done so. Its objection
therefore cannot be considered in review of this petition. See,
e.g., Nat. Res. Defense Council v. Thomas, 805 F.2d 410, 438
(D.C. Cir. 1986) (refusing to “consider the merits of an
objection to a postcomment period agency action”); Am.
Petroleum Inst. v. Costle, 665 F.2d 1176, 1190 (D.C. Cir. 1981)
(same for an objection to a study received by EPA “after the
close of the comment period”).

     We note that EPA did not assert this bar—and are
somewhat baffled by its neglect of a rule protecting it from
judicial intervention over a claim that it had had no opportunity
to evaluate. See Mexichem Specialty Resins, Inc. v. EPA, 787
F.3d 544, 553 (D.C. Cir. 2015). But Respondent-Intervenors
Utility Air Regulatory Group and Union Electric Company
properly preserved the argument. Based on the former’s
supplemental submission, we find that it had associational
                               10

standing to do so. See Letter from Lucinda Minton Langworthy
(Sept. 13, 2018), Doc. No. 1750501.

     In its reply brief, Sierra Club invites us to find its
mathematical fix objection nestled within its March 2016
Comment, which it describes as objecting that “available
information demonstrates that Gallia County is in
nonattainment.” Sierra Club’s Reply Br. 14; see also Letter
from Zachary M. Fabish, Staff Attorney, Sierra Club to
Amparo Castillo, Docket Manager, EPA (Mar. 31, 2016), J.A.
409, 419 [hereinafter Sierra Club Comment]; cf. 42 U.S.C.
§ 7407(d)(1)(A)(iii) (defining “unclassifiable” as “any area that
cannot be classified on the basis of available information as
meeting or not meeting” the NAAQS); id. § 7407(d)(3)(A)
(authorizing EPA to redesignate an area when “available
information indicates that the designation . . . should be
revised”). But a mere reference to “available information”
plainly cannot qualify as posing with “reasonable specificity”
Sierra Club’s present contention that reversing Ohio’s 38%
discount would lead ineluctably to a nonattainment
designation—at least not if Congress’s regulatory structure is
to be preserved.

     Moreover, when Sierra Club spoke of “available
information” in its March 2016 Comment, it was apparently
referring to its own modeling—not Ohio’s. See Sierra Club
Comment at 11, J.A. 419. In any event, Sierra Club necessarily
meant information in EPA’s hands as of that time—not
information that would reach EPA only in April 2016.

    Sierra Club had a path to judicial review of its present
claim. The Act provides an orderly process for raising
objections that a party had no opportunity to press during the
public comment period. Under 42 U.S.C. § 7607(d)(7)(B),
when the “grounds” for an objection “arose after the period for
public comment,” and the “objection is of central relevance to
                               11

the outcome of the rule,” id., the objecting party must “petition
EPA for administrative reconsideration before raising the
issue” in this court, EME Homer City Generation, L.P. v. EPA,
795 F.3d 118, 137 (D.C. Cir. 2015) (emphasis added).

     Sierra Club’s sophisticated lawyers are of course aware of
this provision and in fact filed such a reconsideration petition
in part to raise the group’s proposed mathematical fix. Sierra
Club’s Br. 9. The petition quite correctly asserted that “The
Grounds For [Its] Objections Arose After The Close Of The
Public Comment Period.” Letter from Tony Mendoza, Staff
Attorney, Sierra Club, to Gina McCarthy, Administrator, EPA,
at 2 (Jan. 6, 2017), J.A. 619 (emphasis added) (paraphrasing 42
U.S.C. § 7607(d)(7)(B)). That claim, clearly, can’t be squared
with Sierra Club’s theory here—that its objection satisfied the
statute’s requirement that it have been raised “during the period
for public comment.” 42 U.S.C. § 7607(d)(7)(B) (emphasis
added).

     The fate of the petition for reconsideration, though not
strictly relevant, deserves mention. As Sierra Club observes,
“EPA purported to grant [the petition], but instead agreed only
‘to evaluate when available, three years (calendar years 2017
through 2019) of ambient air-quality-monitoring data that will
result from SO2 monitors.’” Sierra Club’s Br. 9 (quoting Letter
from Gina McCarthy, Administrator, EPA, to Tony G.
Mendoza, Staff Attorney, Sierra Club (Jan. 18, 2017), J.A.
617). Sierra Club characterizes this as a grant “in name only.”
Sierra Club’s Reply Br. 2.

     Again, perhaps so. And perhaps Sierra Club could have
petitioned for review of EPA’s reconsideration order by
claiming that the “grant” was functionally a denial. See, e.g.,
Mexichem, 787 F.3d at 553–54. That, at least, would have
properly teed up the reconsideration proceeding—the only
context in which we would be entitled to consider EPA’s
                               12

treatment of the 38% discount theory. Because Sierra Club has
not petitioned us to review that proceeding, however, we may
not do so now. See, e.g., LaRouche’s Comm. for a New Bretton
Woods v. FEC, 439 F.3d 733, 739 (D.C. Cir. 2006).

     Finally, Sierra Club invokes a statement that has appeared
in a few of our cases: EPA “retains a duty to examine key
assumptions,” and therefore “must justify [those]
assumption[s] even if no one objects . . . during the comment
period.” Nat. Res. Defense Council v. EPA, 755 F.3d 1010,
1023 (D.C. Cir. 2014) (quoting Appalachian Power Co. v. EPA,
135 F.3d 791, 818 (D.C. Cir. 1998)); see Sierra Club’s Reply
Br. 16. But after a “single, conclusory” sentence, Sierra Club
fails to “further develop” the argument. United States v. TDC
Mgmt. Corp., 827 F.3d 1127, 1130 (D.C. Cir. 2016) (quoting
Bryant v. Gates, 532 F.3d 888, 898 (D.C. Cir. 2008)). And “it
is not our practice to” finish the job ourselves. Am. Freedom
Defense Initiative v. Wash. Metro. Transit Auth., 901 F.3d 356,
369 n.6 (D.C. Cir. 2018); see also Schneider v. Kissinger, 412
F.3d 190, 200 n.1 (D.C. Cir. 2005) (“It is not enough merely to
mention a possible argument in the most skeletal way, leaving
the court to do counsel’s work . . . . [A] litigant has an
obligation to spell out its arguments squarely and distinctly, or
else forever hold its peace.” (quoting United States v. Zannino,
895 F.2d 1, 17 (1st Cir. 1990))).

     In sum, we hold that Sierra Club’s sole objection was not
“raised . . . during the period for public comment.” 42 U.S.C.
§ 7607(d)(7)(B). And although Sierra Club did raise that
objection in a petition for reconsideration, EPA’s resolution of
that petition is not before us. We thus deny Sierra Club’s
petition for review.
                              13

                            * * *

     Finally we consider EPA’s “unclassifiable” designation
for Colorado Springs. During the comment period, EPA
received modeling purporting to show the area in
nonattainment. But EPA rejected that modeling, which was
based on meteorological data from the Colorado Springs
Airport. EPA explained that such data were not representative
of the area around the Martin Drake Power Plant, the main
emissions source in Colorado Springs. For that reason, EPA
said, models based on the airport meteorological data could not
reliably inform the agency’s designation. See Final Technical
Support Document: Colorado at 15–19, 23, EPA-HQ-OAR-
2014-0464-0393, J.A. 557–61, 565 [hereinafter Colorado Final
Technical Support].

     Masias sees things differently. He argues that EPA
arbitrarily failed to “define representative in any way.”
Masias’s Br. 22; see also Masias’s Reply Br. 3. And he faults
the agency for applying different standards of
representativeness in different areas. See Masias’s Br. 22–23.
Neither argument prevails.

    Masias’s first contention runs headlong into EPA’s
guidelines for air quality modeling. These provide that
“meteorological data used as input . . . should be selected on
the basis of spatial and climatological (temporal)
representativeness.” 40 C.F.R. pt. 51, App. W § 8.4(b). The
guidelines     then    explain     how       EPA      assesses
“representativeness”:

    The representativeness of the measured data is dependent
    on numerous factors including, but not limited to: (1) The
    proximity of the meteorological monitoring site to the area
    under consideration; (2) the complexity of the terrain; (3)
                              14

    the exposure of the meteorological monitoring site; and (4)
    the period of time during which data are collected.

40 C.F.R. pt. 51, App. W § 8.4(b); see also SO2 NAAQS
Designations Modeling Technical Assistance Document at 26
(draft Feb. 2016), J.A. 321.

     EPA reasonably applied those guidelines here. See
Colorado Final Technical Support at 13, J.A. 555. The agency
identified significant differences in terrain and wind patterns
between the airport and the Drake plant. With respect to
terrain, the agency reasonably noted that the elevation near the
airport (about 600 feet) was “moderate” when compared to the
elevation—owing to the Rocky Mountains—near the Drake
plant (about 4000 feet). Id. at 16 & n.4, J.A. 558.

     These differences in terrain, EPA further found, drove
differences in wind speeds and directions. Specifically, winds
at the Drake plant, following the Fountain Creek Valley,
predominantly flow northwest and southeast, whereas winds at
the airport, “driven by the higher terrain to the north,” mostly
flow north and south, id., as shown here:
                                15




Id. at 16 fig.4, J.A. 558. Similar differences in direction, not to
mention speed, can be seen, the agency concluded, through a
comparison of meteorological data collected at both sites, as
shown in the following figures (known as wind roses):
                              16




            Meteorological Data from Drake Plant




     Meteorological Data from Colorado Springs Airport

Id. at 17–18 figs.5–6, J.A. 559–60.
                               17

    All in all, these differences, EPA explained, would
“significantly impact the transport and dispersion conditions of
[SO2] plumes” in both areas. Responses to Significant
Comments on the Designation Recommendations for the 2010
Sulfur Dioxide Primary National Ambient Air Quality
Standard (NAAQS) at 21, EPA-HQ-OAR-2014-0464-0389
(June 30, 2016), J.A. 518 [hereinafter Responses to Significant
Comments]. On that basis, the agency concluded that the
meteorological data from the airport were not representative of
the Colorado Springs area and, accordingly, could not provide
an appropriate basis for the agency’s designation. Id.; see also
Colorado Final Technical Support at 19, J.A. 561.

     In short, EPA reasonably relied on a multi-factor test to
reject the data here. As we have observed in a related context,
“discrete data points are not determinative” because, by its
“very nature,” a multi-factor test “is designed to analyze a wide
variety of data on a case-by-case basis.” ATK Launch Sys., Inc.
v. EPA, 669 F.3d 330, 336 (D.C. Cir. 2012) (internal quotation
marks omitted) (quoting Catawba Cnty., 571 F.3d at 46). Thus,
it is “EPA’s holistic assessment of numerous factors [that]
drives the process—no single factor determines a particular
designation.” Id. (quoting Catawba Cnty., 571 F.3d at 46).

     Masias also claims that “EPA used a different standard for
judging representativeness of meteorological data for Colorado
Springs versus” four other areas. Masias’s Br. 22. But only a
fragment of that theory was raised before the agency; we
review the fragment and find it wanting.

     As already noted at some length, the act limits our review
to “[o]nly” those objections that were “raised with reasonable
specificity during the period for public comment.” 42 U.S.C. §
7607(d)(7)(B). Although Masias need not have personally
raised his current objection during the comment period, see Ne.
Md. Waste Disposal Auth. v. EPA, 358 F.3d 936, 948 n.12
                               18

(D.C. Cir. 2004), he must point us to a commenter who did, see
Fed. R. App. P. 28(a)(8)(A) (requiring briefs to contain
citations to “parts of the record” relied upon). That commenter
must have stated Masias’s current objection in a “clear enough”
way to have “place[d] the agency ‘on notice.’” Nat’l Ass’n of
Clean Air Agencies v. EPA, 489 F.3d 1221, 1231 (D.C. Cir.
2007) (quoting Mossville Envtl. Action Now v. EPA, 370 F.3d
1232, 1240 (D.C. Cir. 2004)).

     Here, Masias relies on a single sentence from a 14-page
expert report. See Masias’s Reply Br. 10. In that report Dr. H.
Andrew Gray argued that the Colorado Springs Airport data
were sufficiently representative of the Colorado Springs area.
See Expert Report and Statement of Dr. H. Andrew Gray at 8–
14 (Mar. 30, 2016), J.A. 367–73. On the tenth page of that
report, he noted in passing EPA’s different treatment of
meteorological data from different areas. He claimed that it “is
common” to use “surface meteorological data . . . that are from
airports located much further away” from the emissions source
than the Colorado Springs Airport. Id. at 10, J.A. 369. At no
point, though, did Dr. Gray bring any specific areas to EPA’s
attention or draw contrasts based on any factor other than
proximity.

       We take Dr. Gray’s comment to adequately raise the
objection that EPA’s weighing of the proximity of
meteorological data for Colorado Springs differed from its
weighing of proximity for other areas. EPA addressed this
comment head on. The agency “agree[d] that it is acceptable
in some cases to use meteorological data collected at an airport
. . . that may be located a significant distance from the modeled
source.” Responses to Significant Comments at 31, J.A. 528.
But EPA also explained that it had relied on such distant airport
meteorological data where the data, overall, were
“representative of the meteorological conditions at the location
of the modeled source,” and that this was not so for the airport
                               19

and power plant here. Id. The finding of representativeness in
other instances rested, EPA said, on the multi-factor test
described above, which, as applied to Colorado Springs,
militated against finding the airport data representative. See
id.; Colorado Final Technical Support at 13–19, J.A. 555–61.

     Because “EPA is not required ‘to cull through all the letters
it receives and answer all of the possible implied arguments,’”
Nat’l Ass’n of Clean Air Agencies, 489 F.3d at 1231 (quoting
Mossville, 370 F.3d at 1231), Dr. Gray’s argument (the only
one adduced by Masias as raising his broad claim) did not put
the agency on notice that it needed to defend its weighing of
other factors, such as terrain and wind speeds, across different
areas. Our finding that EPA adequately addressed Dr. Gray’s
concern therefore disposes of Masias’s claim of agency
inconsistency across sites.

    We therefore deny Masias’s petition for review.


                             * * *

     For the foregoing reasons, we dismiss the Board’s petition
for lack of standing and deny Sierra Club’s and Masias’s
petitions for review.

                                                     So ordered.
