 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued April 16, 2014              Decided August 15, 2014

                        No. 13-1194

                OTIS ELEVATOR COMPANY,
                       PETITIONER

                             v.

               SECRETARY OF LABOR, ET AL.,
                     RESPONDENTS


   On Petition for Review of a Final Order of the United
 States Occupational Safety & Health Review Commission


    Stephen C. Yohay argued the cause for petitioner. With
him on the briefs were John A. Shedden and Paul J. Waters.

    Scott Glabman, Senior Appellate Attorney, U.S.
Department of Labor, argued the cause for respondents. With
him on the brief were Joseph M. Woodward, Associate
Solicitor for Occupational Safety and Health, and Heather R.
Phillips, Counsel for Appellate Litigation.

    Before: ROGERS, SRINIVASAN and MILLETT, Circuit
Judges.

    Opinion for the Court by Circuit Judge MILLETT.
                              2
     MILLETT, Circuit Judge: A service mechanic employed
by Otis Elevator Company injured his hand while unjamming
the gate of a freight elevator. The accident spurred an
investigation by the Occupational Safety and Health
Administration (OSHA), and ultimately a citation to Otis
Elevator for violating OSHA safety standards involving the
control of hazardous energy. The Occupational Safety and
Health Review Commission upheld the citation, and Otis
Elevator petitions for review of that decision. Specifically,
Otis Elevator argues that the OSHA safety standards allegedly
violated did not apply to the work its mechanic was
performing at the time of the accident. Because the
Commission’s determinations that the safety standards
applied to the mechanic’s work and were violated are neither
arbitrary nor capricious, and are supported by substantial
evidence, we deny the petition for review.

                     I.   BACKGROUND

        A. Statutory and Regulatory Framework

    Congress enacted the Occupational Safety and Health Act
of 1970, 29 U.S.C. §§ 651–678 (OSH Act), “to assure so far
as possible * * * safe and healthful working conditions” for
“every working man and woman in the Nation.” 29 U.S.C.
§ 651(b). The Act charges the Secretary of Labor with
promulgating workplace health and safety standards, id. at
§ 655, and imposing citations and monetary penalties on
employers who fail to comply with those standards, id. at
§§ 658–659, 666.

    An employer who disagrees with the Secretary’s
imposition of a citation or penalty can seek review before the
Occupational Safety and Health Review Commission, 29
U.S.C. §§ 651(b)(3) & 661, which must provide an objecting
employer with an evidentiary hearing and a written decision
                              3
based on findings of fact, id. at § 659(c). See also Martin v.
Occupational Safety & Health Review Comm’n, 499 U.S. 144,
147-148 (1991). Initially, an administrative law judge
reviews the Secretary’s order. 29 U.S.C. § 661(j). The
Commission may, in its discretion, review the administrative
law judge’s decision de novo, without any deference to his or
her fact findings, credibility judgments, or legal
determinations. Id.; Falcon Steel Co., 16 O.S.H. Cases
(BNA) 1179, 1993 WL 155690, at *7 (O.S.H.R.C. 1993)
(“The Commission’s reviewing authority includes the
authority to decide all issues it could decide as the initial
decision-maker.”).

     Either the Secretary or the employer may seek judicial
review of the Commission’s final order directly in a United
States court of appeals, which “must treat as ‘conclusive’
Commission findings of fact that are ‘supported by substantial
evidence.’” Martin, 499 U.S. at 148 (citing 29 U.S.C.
§ 660(a)-(b)).

     In 1989, the Secretary exercised his rulemaking authority
to prescribe safety requirements for “the control of hazardous
energy.” OSHA Control of Hazardous Energy Sources
(Lockout/Tagout) Rule, 29 C.F.R. § 1910.147 (1989). That
standard, commonly referred to as the “lockout/tagout”
standard, “addresses practices and procedures that are
necessary to disable machinery or equipment and to prevent
the release of potentially hazardous energy while maintenance
and     servicing     activities  are    being     performed.”
Lockout/Tagout, 54 Fed. Reg. 36,644-01 (Sept. 1, 1989). To
“lockout” or “tagout” a piece of equipment or machinery
means to affix a device, or to otherwise take steps to disable
equipment or machinery during maintenance or repair. See 29
C.F.R. § 1910.147(a)(3)(i), (b).         By regulation, the
lockout/tagout standard applies to “the servicing and
                              4
maintenance of machines and equipment in which the
unexpected energization or start up of the machines or
equipment, or release of stored energy could cause injury to
employees.”     29 C.F.R. § 1910.147(a)(1)(i) (“scope
provision”).

     The Secretary charged Otis Elevator with violating a
standard requiring the exchange of lockout/tagout information
between on-site and outside employers involved in
maintenance or repair activities. That “information exchange
provision” applies “[w]henever outside servicing personnel
are to be engaged in activities covered by the scope and
application of this standard,” and requires that “the on-site
employer and the outside employer shall inform each other of
their respective lockout or tagout procedures.” 29 C.F.R.
§ 1910.147(f)(2)(i).

                 B. Factual Background

     In June 2009, Otis Elevator dispatched one of its service
mechanics to the Boston Store in Brookfield, Wisconsin, to
repair a jammed metal gate on a freight elevator. When he
arrived at the store, the mechanic spoke with a couple of
Boston Store employees who confirmed that the gate on the
elevator car was “hung up.” An out-of-order sign had been
placed near the elevator. Neither upon the mechanic’s arrival
nor at any other time prior to this incident did Otis Elevator
provide the Boston Store with a copy of its lockout/tagout
procedures.

     When functioning properly, chain assemblies on the
rooftop of the elevator car raise and lower the metal gate.
Upon inspection, however, the mechanic found that the gate
was partially open and could not be moved, leaving a three-
foot gap between it and the floor.
                               5
     The mechanic ducked underneath the gate, and then used
a ladder to climb on top of the elevator car to perform the
repair. He flipped two switches to prevent anyone from
calling the elevator or moving the gate electronically. The
mechanic failed, however, to block up the gate mechanically
in order to prevent unexpected gate movement, as Otis
Elevator’s own mechanical repair processes, captioned
“LOCKOUT/TAGOUT PROCEDURE,” advised.

     Once on top of the elevator car, the mechanic determined
that the gate could not be moved because one of the chains
was “off the sprocket” and jammed. He decided to fix the gate
by prying the chain back onto the sprocket. Once unjammed,
the chain immediately started moving. The mechanic realized
that, as a result of the abrupt release of the jam, the gate was
about to slam down and break the chain’s connecting link. He
reacted by grabbing the chain, which “drug” his hand through
the sprocket and chain, resulting in a serious laceration to his
finger.

                   C. Procedural History

    Following OSHA’s investigation of the accident, the
Secretary cited Otis Elevator for violating the lockout/tagout
standard, 29 C.F.R. §§ 1910.147 et seq. Specifically, the
Secretary determined that Otis Elevator failed to comply with
29      C.F.R.      § 1910.147(f)(2)(i)—the     lockout/tagout
“information exchange provision,” which required Otis
Elevator, as the “outside employer” in this incident, to give
advance notice to the “on-site employer,” the Boston Store, of
the lockout/tagout procedures it would use when it had to
repair the freight elevator.

    Otis Elevator contested that citation. An administrative
law judge vacated it, reasoning that the lockout/tagout
standard’s “scope provision” did not apply because the startup
                              6
of the machine once the chain was forced back onto the
sprocket was anticipated by the mechanic, not “unexpected”
energization, within the meaning of 29 C.F.R.
§ 1910.147(a)(1)(i). Otis Elevator Co., OSHRC Docket No.
09-1278, 2011 WL 10604073, at *18 (ALJ Jan. 14, 2011)
(“ALJ Dec.”).

     The administrative law judge also ruled that Otis Elevator
was not in violation of the lockout/tagout “information
exchange provision,” 29 C.F.R. § 1910.147(f)(2)(i), because
no Boston Store employees were actually in danger of being
injured. ALJ Dec. at *18. The only “zone of danger,” the
administrative law judge found, was on top of the elevator
car, where there was no reasonable prospect of entry by
anyone other than the mechanic himself. ALJ Dec. at *19.

     Reviewing the case de novo, the Commission disagreed
and reinstated the Secretary’s citation. The Commission
ruled, first, that the lockout/tagout standard applied to the
mechanic’s work. Otis Elevator Co., OSHRC Docket No. 09-
1278, 24 O.S.H. Cases (BNA) 1081, 2013 WL 3998034, at
*2-*4 (Rev. Comm’n April 8, 2013) (“Comm’n Dec.”) The
Commission explained that the applicability of the
lockout/tagout standard turns not on the mechanic’s
subjective prediction of how the machine would operate at the
moment of repair, but rather on whether there was a potential
for the unexpected release of stored energy that could cause
injury to the mechanic or others. The Commission found
such potential in this case because, as the mechanic testified,
he could not predict when the jam would yield, making the
sudden release of the chain “unexpected” within the meaning
of 29 C.F.R. § 1910.147(a)(1)(i). Comm’n Dec. at *3.

    The Commission further found that the repair posed a
“caught-in” hazard to the mechanic, since a body part or piece
                               7
of clothing could have been inadvertently caught in the
moving chain. It also posed a significant risk to others
because, in light of the mechanic’s failure to properly block
up the gate consistent with Otis Elevator’s procedures, the
gate could have slammed shut once the chain was unjammed.
Comm’n Dec. at *4 & n.3.

     Having concluded that the lockout/tagout regime applied,
the Commission ruled that Otis Elevator violated the
information       exchange        provision,      29     C.F.R.
§ 1910.147(f)(2)(i), by failing to inform Boston Store
employees of its lockout/tagout procedures prior to
performing maintenance work on the elevator. Comm’n Dec.
at *5-*7. The Commission reasoned that, by its own terms,
the information exchange provision applies “whenever”
outside service personnel are to be engaged in activities
covered by the lockout/tagout standards, and not, as Otis
Elevator argued, only when employees were actually affected
by the work. Comm’n Dec. at *5 (quoting 29 C.F.R.
§ 1910.147(f)(2)(i)).     In the Commission’s view, the
information exchange provision “presumes that in this
situation a Boston Store employee may interfere with ‘the
restrictions and prohibitions’ of Otis Elevator’s energy control
program,” and so compliance with the provision is required
“whenever employers engage in covered maintenance
activity.” Comm’n Dec. at *5 (citing Joseph J. Stolar
Construction Co., 9 O.S.H. Cases (BNA) 2020, 1981 WL
18789, at *5 n. 9 (O.S.H.R.C. 1981) (“The Commission has
held that, when a standard prescribes specific means of
enhancing employee safety, [a] hazard is presumed to exist if
the terms of the standard are violated.”)).

     While the Commission reinstated the Secretary’s citation,
it reduced the penalty to $500 on the ground that the
likelihood of an accident was exceptionally low because a
                                8
Boston Store employee had placed an out-of-order sign by the
elevator, only a limited number of Boston Store employees
were present during the early morning repair, and Boston
Store employees had no responsibility for servicing the
elevator while the Otis Elevator mechanic was performing his
work. Comm’n Dec. at *9.

    Otis Elevator timely petitioned for review.

                  II. STANDARD OF REVIEW

       In reviewing Commission decisions, this court accepts
the Commission’s findings of fact as “conclusive” if they are
“supported by substantial evidence on the record considered
as a whole,” 29 U.S.C. § 660(a), and the Commission’s
application of the law to those facts will be overturned only if
it is arbitrary, capricious, an abuse of discretion, or contrary to
law. See Fabi Construction Co. v. Secretary of Labor, 370
F.3d 29, 33 (D.C. Cir. 2004) (quoting Administrative
Procedure Act, 5 U.S.C. § 706(2)(a)). In addition, this court
defers to the Secretary’s interpretation of his own regulations
unless it is unreasonable or plainly contradicts the regulation’s
language or purpose. S.G. Loewendick & Sons, Inc. v. Reich,
70 F.3d 1291, 1294 (D.C. Cir. 1995).

                         III. ANALYSIS

     Otis Elevator challenges the Commission’s decision on
two grounds. First, it contends that the lockout/tagout
standards do not apply at all because there was no
“unexpected” release of energy in this repair. Second, Otis
Elevator argues that it had no duty to exchange information
about its lockout/tagout procedures with the Boston Store
because the nature, location, and timing of the repair did not
put any employees or customers at risk.
                               9
     Neither argument succeeds.             The Commission
permissibly concluded that the lockout/tagout protocols
applied because there was stored kinetic energy in the
jammed chain due to the weight of the gate that posed a
danger to the mechanic and to anyone nearby; and the exact
timing of the chain assembly’s energization was unknown.
The Commission likewise reasonably concluded that, to
promote safety, its regulations require the proactive exchange
of information in advance of repairs regardless of any post
hoc assessment of risk on a repair-by-repair basis. For those
reasons, we deny the petition for review.

     A. Applicability of the Lockout/Tagout Protocol

    The lockout/tagout standard applies to the servicing and
maintenance of machines and equipment “in which the
unexpected energization or start up of the machines or
equipment, or release of stored energy could cause injury to
employees.”      29 C.F.R. § 1910.147(a)(1)(i).          The
Commission’s factual determination that the mechanic’s
unjamming repair triggered both prongs of that test was
supported by substantial evidence, and its application of the
OSHA regulations to those facts was permissible.

     1. The Commission found that the repair entailed a
release of stored energy that was both unexpected and created
the potential for injury. Those findings sufficed to trigger the
lockout/tagout regime, and both of them are substantially
grounded in the administrative record.

     First, the Commission found—and Otis Elevator does not
dispute—that “there was stored kinetic energy in the
elevator’s jammed chain assembly due to the weight of the
partially open gate.” Comm’n Dec. at *3. Indeed, the
mechanic’s concern that the sudden and overlooked release of
                              10
that energy would cause the gate to slam down is what
prompted him to grab the chain and lacerate his hand. Id.

     The Commission further found that the stored energy
“could cause injury to employees.”                  29 C.F.R.
§ 1910.147(a)(1)(i). To begin with, the mechanic himself
testified that, because only one counterweight was holding the
gate, “it would have slammed shut once the chain was
unjammed.” Comm’n Dec. at *4 n.3. Moreover, Boston
Store employees “were present at the store and had access to
the elevator gate while the Otis mechanic was servicing the
elevator,” putting them at risk of significant injury when that
gate abruptly came down. Comm’n Dec. at *5 n.8.

     Confirming the point, Otis Elevator’s “Lockout/Tagout
Procedure[s]” specifically included an energy control
measure—blocking up the gate with a Bi-Parting Door
Tool—that would have protected against the hazard created
by the gate slamming down. Comm’n Dec. at *2 n.2; JA 378.
The mechanic neglected to employ that safety measure in this
case. Id. Had he done so, he would have both eliminated the
risk to the public and averted the concern about a crashing
gate that prompted him to injure himself by grabbing the
rapidly moving chain.

     The repair posed a risk of injury in still another respect.
The Commission separately found that the release of the
chain’s stored energy “posed a caught-in hazard to the
mechanic” himself, because “his work necessarily placed him
in close proximity to [the chain], and a body part or piece of
clothing could have been inadvertently caught in the chain, or
between it and the sprocket, when the stored energy released.”
Comm’n Dec. at *4. The mechanic’s own testimony and
conduct substantiated the Commission’s judgment. He
admitted that he was close enough to the chain to grab it with
                              11
his hand—in fact, he did just that—which meant he was also
close enough to get his clothes or a body part inadvertently
caught in the moving chain.

    Second, the Commission found that the repair involved
“unexpected energization.” 29 C.F.R. § 1910.147(a)(1)(i).
Specifically, while the mechanic knew that the chain
assembly would start to move once it was unjammed, the
mechanic could not “predict when the jam would yield.”
Comm’n Dec. at *3.

     Otis Elevator stresses that the mechanic knew what
would happen when the repair occurred, and thus the release
of energy was not “unexpected.” But what is critical to the
standard’s application in this case is that the mechanic did not
know when that moment would arrive. No mechanism on the
elevator, for instance, signaled when the jam would yield or
the chain would begin to move.

     This case thus is unlike Reich v. General Motors
Corporation, 89 F.3d 313 (6th Cir. 1996), on which Otis
Elevator relies. In Reich, the machines under repair were
specifically designed not to start up until an eight to twelve
step process was completed, and “audible or visual signals
* * * alerted servicing employees that the machines were
about to start up.” Id. at 314-315. Here, by contrast, the only
notice the mechanic had that the chain assembly would start
moving was the movement itself. Indeed, as the Commission
found, “the mechanic’s own testimony shows that the release
of energy surprised him.” Comm’n Dec. at *3.

     Otis Elevator also argues that the finding of unexpected
energization contradicts the administrative law judge’s
finding that the mechanic “expected” the gate to move once
he placed the chain back on to the sprocket. That argument
misses the mark because it overlooks both (i) the
                              12
Commission’s focus on when, not whether, the chain
assembly would energize, and (ii) the Commission’s full
authority under the OSH Act to find facts independently
without any deference to the administrative law judge. 29
U.S.C. § 661; see Falcon Steel Co., 1993 WL 155690, at *7.

     2. Just as we find no factual error in the Commission’s
determinations, we hold that the Commission’s application of
the OSHA regulations to those substantiated facts was neither
arbitrary nor capricious.

     To begin with, the plain text of the lockout/tagout
standard extends to the “unjamming of machines or equipment
* * * where the employee may be exposed to the unexpected
energization or start up of the equipment or release of
hazardous energy.” 29 C.F.R. § 1910.147(b) (emphasis
added). Indeed, in promulgating the final rule, OSHA not
only repeatedly cites “unjamming” work as one of the
activities covered by the standard, see 54 Fed. Reg. at 36,646,
36,647, 36,648, 36,652, 36,661 & 36,688, but in fact lists
“unjamming object(s) from equipment” as statistically the
most common source of the workplace injuries that the
standard seeks to prevent, see id. at Tables III & XII.

     In that vein, the Commission’s conclusion that the
lockout/tagout standard applies also comports with the
standard’s preventative purpose. See Buffalo Crushed Stone,
Inc. v. Surface Transportation Board, 194 F.3d 125, 128
(D.C. Cir. 1999) (“We will defer to the agency’s
interpretation so long as it ‘sensibly conforms to the purpose
and wording of the regulations.’”) (quoting Martin, 499 U.S.
at 150-151). As OSHA explained in promulgating the final
rule, one of “the most effective method[s] to prevent
employee injury caused by the unanticipated movement of a
component of a machine” is to “utilize a restraining device to
                              13
prevent movement,” such as “by blocking material or
components.” 54 Fed. Reg. at 36,647. Indeed, such blocking
of the elevator gate was the very mechanism that Otis
Elevator’s own lockout/tagout procedures prescribed, but the
mechanic omitted. Comm’n Dec. at *2 n.2; JA 383. That
close similarity between the hazards identified in the
preamble to the rule and the activity that prompted the citation
reinforces the reasonableness of the enforcement action. See
Burkes Mechanical, Inc., 21 O.S.H. Cases (BNA) 2136, 2007
WL 2046814, at *5 (O.S.H.R.C. 2007).

     The Commission’s decision also comports with prior
agency decisions. In Dayton Tire, 23 O.S.H. Cases (BNA)
1247, 2010 WL 3701876, at *4 (O.S.H.R.C. 2010), aff’d in
relevant part by Dayton Tire v. Secretary of Labor, 671 F.3d
1249 (D.C. Cir. 2012), General Motors, 22 O.S.H. Cases
(BNA) 1019, 2007 WL 4350896, at *3 (O.S.H.R.C. 2007),
and Burkes Mechanical, Inc., 2007 WL 2046814, at *4 n.4,
the Commission held that the lockout/tagout standard applied
to repairs that, as here, provided the employees no advance
notice of when the machine or equipment would release
stored energy, see Dayton Tire, 2010 WL 3701876, at *4;
General Motors, 2007 WL 4350896, at *3; Burkes
Mechanical, 2007 WL 2046814, at *4 n.4.

     For those reasons, it was neither arbitrary nor capricious
for the Commission to find that the lockout/tagout standard
applied to the unjamming activity being performed by the
Otis Elevator mechanic in this case.

    B. Applicability of the Information Exchange Rule

    The Commission cited Otis Elevator for failing to
exchange its lockout/tagout procedures with the Boston Store
before conducting the repair, as required by 29 C.F.R.
§ 1910.147(f)(2)(i). Otis Elevator objects that, in so ruling,
                               14
the Commission wrongly presumed that this failure exposed
employees to a hazard, rather than proved the actual existence
of that danger. We hold that the Commission’s interpretation
and application of its regulation was reasonable as a matter of
fact and law.

    The citation was factually reasonable because the
Commission specifically found that the mechanic’s repair
work exposed Boston Store employees in the building to a
zone of danger in that they “were present at the store and had
access to the elevator gate while the Otis mechanic was
servicing the elevator,” and the slamming down of the gate
could have harmed a person in its path. Comm’n Dec. at *4
n.3 & *5 n.8.

     Once employee exposure to the repair area—including
the elevator gate—was established, the Commission’s
interpretation of the regulation to presume a hazard to those
employees from the failure to exchange information was also
legally reasonable.      OSHA standards are “unofficially
divided” into “specification” and “performance” standards.
See Mark A. Rothstein, Occupational Safety & Health Law
§ 5:3 (2013 ed.). Specification standards “detail the precise
equipment, materials, and work processes required to
eliminate hazards,” while performance standards “indicate the
degree of safety and health protection to be achieved, but are
more flexible and leave the method of achieving the
protection to the employer.” Id. (citing Secretary of Labor v.
Thomas Industrial Coatings, Inc., 21 O.S.H. Cases (BNA)
2283, 2007 WL 4138273 (O.S.H.R.C. 2007)). *


*
 See also Joseph J. Stolar Construction Co., 1981 WL 18789, at *5
n.9 (“When a standard prescribes specific means of enhancing
employee safety, a hazard is presumed to exist if the terms of the
standard are violated.”); Fabricated Metal Products, Inc., 18
                                15
     In this case, the Commission fairly read the exchange
provision to be a specification standard that presumes a
hazard if information is not exchanged and, for that reason,
categorically requires the exchange of lockout/tagout
information in advance of any covered repair work. Comm’n
Dec. at *5 & n.7.

    To begin with, that reading is grounded in the
regulation’s plain text, which provides that the repair
company and the on-site employer “shall inform each other”
about their respective lockout or tagout procedures “whenever
outside personnel are to be engaged in activities covered by
the scope and application of this standard.” 29 C.F.R.
§ 1910.147(f)(2)(i) (emphases added); see also 54 Fed. Reg.
at 36,680 (the exchange provision’s requirements “are
necessary when outside personnel work on machines or
equipment”) (emphasis added). The regulation’s use of
mandatory directives like “shall” and “whenever” defy the
optionality in operation that Otis Elevator favors.

    The preamble to the rule’s promulgation echoes the
presumption of risk, explaining that the exchange provision
“ensure[s] that both the employer and the outside service
personnel are aware that their interaction can be a possible
source of injury to employees and that the close coordination


O.S.H. Cases (BNA) 1072, 1997 WL 694096, at *2 n.4
(O.S.H.R.C. 1997) (“As to a specification standard * * * proof of
noncompliance with the standard establishes the existence of a
hazard.”); see also Occupational Safety & Health Law § 5:24
(“Before promulgating a standard the Secretary is required to
consider the need for each measure of safety and health protection.
Therefore, the Secretary is not ordinarily required to prove the
existence of a hazard each time a standard is enforced because the
promulgation of a standard presupposes the existence of a hazard.”)
(collecting cases).
                               16
of their activities is needed in order to reduce the likelihood of
such injury.” 54 Fed. Reg. at 36,680-36,681. Requiring the
Secretary to prove actual risk on a case-by-case basis would
erode the regulation’s prophylactic protection.

     Otis Elevator presses five challenges to the
Commission’s interpretation, but none of them succeed.
First, Otis Elevator points to OSHA’s Lockout/Tag-Out
Compliance Directive, CPL 02-00-147 (Feb. 11, 2008), which
establishes OSHA’s enforcement policy for its lockout/tagout
standard.     The Directive, at one point, describes the
information exchange process as “performance-oriented.”
OSHA Directive at 3-57. Read in context, however, the
reference to “performance-oriented” applies to which energy
control procedures to use—the service company’s, the on-site
employer’s, or a combination thereof. See id. (“The
performance-oriented nature of the standard permits the
outside (contractor) employer to use either: the host
employer’s energy control procedure, which some companies
will require; its own procedures; or a combination of the two
procedures, provided the resulting procedure meets the
requirements of the [lockout/tagout] standard.”).

     The Directive, in other words, used its “performance-
oriented” language to clarify that the mandatory exchange of
information does not eliminate the service company’s on-site
discretion to select which of those exchanged procedures is
most appropriately employed in undertaking a repair.
Importantly, at no point does the Directive suggest that
employers are free to choose whether they will comply with
the information exchange provision at all. Quite the opposite,
the Directive states just a few sentences later that “[o]n-site
employers and outside employers must inform each other of
their respective [lockout/tagout] procedures.” Id. (emphasis
added).
                               17
     Second, Otis Elevator invokes a paragraph in the OSHA
Directive stating that, “in all cases, the decision to issue
§ 1910.147 citations to the host or contractor employer should
be based on all of the relevant facts and the established policy
for exposing, creating, correcting, and controlling employers.”
Id. at 2-31. But that provision simply empowers the Secretary
to exercise prosecutorial discretion in issuing citations; it in
no way invests regulated companies with the discretion to
pick and choose whether and when to comply with the
regulation.

     Third, Otis Elevator argues that the Commission failed to
consider “industry practice” that purportedly treats the
information exchange obligation with greater flexibility.
Because the Commission’s interpretation of the regulation is
reasonable, however, “no reference to industry practice is
necessary.” Brock v. L.R. Willson & Sons, Inc., 773 F.2d
1377, 1387 (D.C. Cir. 1985).

     Fourth, Otis Elevator objects that the Secretary’s citation
imposed a “new” interpretation of the regulation in the course
of adjudication, without fair notice. But the Secretary’s
interpretation as adopted by the Commission is grounded in a
reasonable reading of the regulation’s text and purpose, and
for that reason, this court must defer “even where the
Secretary offers his interpretation in the context of litigation
before the Commission.” S.G. Loewendick & Sons, Inc., 70
F.3d at 1294. That is because “[t]he Secretary’s interpretation
of OSH Act regulations in an administrative adjudication
* * * is agency action, not a post hoc rationalization of it.” Id.
(quoting Martin, 499 U.S. at 157).

     To be sure, this court will not hew to that rule if the
Secretary makes such an abrupt change to a longstanding
interpretation that the cited party is effectively deprived of
                              18
“fair notice.” See Fabi Construction Co. v. Secretary of
Labor, 508 F.3d 1077, 1086-1089 (D.C. Cir. 2007) (no
deference where the Secretary had consistently excluded
certain work from coverage under the regulation, and the
Secretary’s new reading was not discernible from regulatory
text). But that is not this case. Otis Elevator has not
identified any pattern of contrary practice by the Secretary or
contrary interpretations by the Commission. Rather, Otis
Elevator, “by reviewing the regulations and other public
statements issued by the agency,” should have been “able to
identify, with ascertainable certainty, the standards with
which the agency expects parties to conform.” Id. at 1088
(quoting General Elec. Co. v. EPA, 53 F.3d 1324, 1329 (D.C.
Cir. 1995)) (internal quotation marks and citation omitted).

      Fifth and finally, Otis Elevator argues that it did not
violate the information exchange provision because the
mechanic’s repair work did not require any lockout or tagout
procedures. However, the Commission found otherwise,
noting specifically that “Otis’s LOTO [lockout/tagout]
procedures required its mechanic ‘to block up [the gate]
mechanically or with a Bi-Parting Door Tool to prevent
unexpected gate movement,’” and “Otis does not dispute that
the mechanic failed to do this.” Comm. Dec. at *2 n. 2.
Indeed, this finding is amply supported by that fact that the
“LOCKOUT/TAGOUT PROCEDURE” section of Otis
Elevators’ own safety manual explicitly states that “all
sources of stored energy must be neutralized,” and
“mechanical blocking is required” when working on an
elevator. JA 383.
                           *****

    In sum, we hold that the Commission’s finding that Otis
Elevator engaged in maintenance activities covered by the
lockout/tagout standard, 29 C.F.R. § 1910.147(a)(1)(i), was
                             19
both reasonable and supported by substantial evidence. We
further hold that the Commission reasonably affirmed the
Secretary’s citation for violation of the information exchange
provision, 29 C.F.R. § 1910.147(f)(2)(i). The Commission’s
Decision and Order accordingly is affirmed.

                                                  So ordered.
