Ronald P. Mills v. Kitchekan Fuel Corporation (Board decision, August 25, 2026)

BRB final decision. The Benefits Review Board affirmed the administrative law judge's award of black lung benefits. Under 20 C.F.R. § 802.406, a Board decision becomes final 60 days after issuance unless a timely petition for judicial review or a timely request for Board reconsideration is filed. A party may request Board reconsideration within 30 days under 20 C.F.R. § 802.407.

Plain-English summary

Ronald Mills sought black lung benefits after coal mine work for Kitchekan Fuel. The administrative law judge found that he had legal pneumoconiosis, was totally disabled, and that the disease substantially contributed to his disability. The employer and its carrier challenged those findings, citing Mills's long smoking history and contrary medical opinions. The Board held that the judge reasonably credited doctors who explained how coal mine dust contributed to his lung impairment and disability. It upheld the award under the ordinary entitlement rules. The Board did not need to decide whether overtime work gave Mills enough years for the separate 15-year presumption.

Decision snapshot

• Authority: Legal pneumoconiosis under 20 C.F.R. § 718.201; disability causation under 20 C.F.R. § 718.204(c)(1).
• Outcome: Award of black lung benefits affirmed.
• Key point: Credited medical evidence established coal dust's contribution to the disabling lung disease without relying on the 15-year presumption.

Full text (BRB public release)

U.S. Department of Labor Benefits Review Board 200 Constitution Ave. NW
Washington, DC 20210-0001

BRB No. 25-0229 BLA

RONALD P. MILLS
)
)
Claimant-Respondent
)
)
v. )
)
KITCHEKAN FUEL CORPORATION
)
)
and
)
NOT-PUBLISHED
)
WEST VIRGINIA COAL WORKERS’
)
PNEUMOCONIOSIS FUND
) DATE ISSUED: 08/25/2026
)
Employer/Carrier-
)
Petitioners
)
)
DIRECTOR, OFFICE OF WORKERS’
)
COMPENSATION PROGRAMS, UNITED
)
STATES DEPARTMENT OF LABOR
)
)
Party-in-Interest
)
DECISION and ORDER
Appeal of the Decision and Order Awarding Benefits of Lauren C. Boucher, Administrative Law Judge, United States Department of Labor.

Joseph E. Wolfe and Donna E. Sonner (Wolfe Williams & Austin), Norton, Virginia for Claimant.

Wes A. Shumway (Spilman Thomas & Battle, PLLC), Charleston, West Virginia, for Employer and its Carrier.

Before: ROLFE, Acting Chief Administrative Appeals Judge, GRESH and ULMER, Administrative Appeals Judges.
PER CURIAM:

Employer and its Carrier (Employer) appeal the Decision and Order Awarding Benefits (2022-BLA-05656) of Administrative Law Judge (ALJ) Lauren C. Boucher, rendered on a miner’s claim filed on February 7, 2020, pursuant to the Black Lung Benefits Act, as amended, 30 U.S.C. §§901-944 (Act).

The ALJ credited Claimant with thirteen years of coal mine employment and a fifty pack-year smoking history. She found Claimant established all elements of entitlement under 20 C.F.R. Part 718 and awarded benefits without addressing Claimant’s contention that consideration of his overtime hours increases his documented thirteen years of coal mine employment to at least fifteen years in order to invoke the rebuttable presumption at Section 411(c)(4) of the Act, 30 U.S.C. §921(c)(4).1 20 C.F.R. §§718.202(a)(4), 718.204(b)(2), 718.204(c)(1), 718.305.

On appeal, Employer challenges the ALJ’s findings that Claimant established pneumoconiosis, total disability, and disability causation under Part 718. Claimant responds in support of the award and additionally notes he argued he was entitled to invocation of the rebuttable presumption. The Director, Office of Workers’ Compensation Programs, has not filed a response brief in this appeal. Employer filed a reply brief reiterating its contentions.

The Benefits Review Board’s scope of review is defined by statute. We must affirm the ALJ’s Decision and Order if it is rational, supported by substantial evidence, and in accordance with applicable law.2 33 U.S.C. §921(b)(3), as incorporated by 30 U.S.C.
§932(a); O’Keeffe v. Smith, Hinchman & Grylls Assocs., Inc., 380 U.S. 359, 361-62 (1965).

1
Section 411(c)(4) of the Act provides a rebuttable presumption that a miner is totally disabled due to pneumoconiosis if he has at least fifteen years of underground or substantially similar surface coal mine employment and a totally disabling respiratory or pulmonary impairment. 30 U.S.C. §921(c)(4); see 20 C.F.R. §718.305.
2
The Board will apply the law of the United States Court of Appeals for the Fourth Circuit, as Claimant performed his last coal mine employment in West Virginia. See Shupe v. Director, OWCP, 12 BLR 1-200, 1-202 (1989) (en banc); Director’s Exhibit 4; Hearing Tr. at 14.

2
Entitlement under 20 C.F.R. Part 718

To establish entitlement under the Part 718 framework, Claimant must establish disease (pneumoconiosis); disease causation (it arose out of coal mine employment); total disability (a totally disabling respiratory or pulmonary impairment); and disability causation (pneumoconiosis substantially contributed to the disability). 30 U.S.C. §901; 20 C.F.R. §§718.3, 718.202, 718.203, 718.204. Failure to establish any one of these elements precludes an award of benefits. Anderson v. Valley Camp of Utah, Inc., 12 BLR 1-111, 1- 112 (1989); Trent v. Director, OWCP, 11 BLR 1-26, 1-27 (1987).

Legal Pneumoconiosis

“Legal pneumoconiosis” includes any chronic lung disease or impairment and its sequelae arising out of coal mine employment, including any chronic restrictive or obstructive pulmonary disease arising out of coal mine employment. 20 C.F.R.
§718.201(a)(2). A disease “arising out of coal mine employment” is one that is significantly related to, or substantially aggravated by, dust exposure in coal mine employment. 20 C.F.R. §718.201(b). Claimant may establish legal pneumoconiosis through a physician’s reasoned medical opinion based on objective medical evidence. 20 C.F.R. §718.202(a)(4).

The ALJ evaluated four medical opinions. Decision and Order at 28-32. Drs.
Forehand and Green considered Claimant’s thirteen-year coal-mine employment history, substantially longer smoking history, symptoms, and objective testing; both diagnosed chronic obstructive pulmonary disease (COPD) and gas exchange impairment and specifically identified coal mine dust exposure as a significant contributing cause of these conditions. Director’s Exhibit 15; Claimant’s Exhibits 5, 8, 10. Dr. Basheda diagnosed an asthmatic form of obstructive lung disease due to smoking, not coal dust exposure. Director’s Exhibit 18 at 16; Employer’s Exhibit 9 at 35. Although Dr. Zaldivar opined “there is no evidence of any pulmonary impairment at all,” he nevertheless recognized mild obstruction, hypoxemia, and reduced forced vital capacity on pulmonary function and blood gas testing, but he attributed it to smoking and obesity rather than coal mine dust exposure. Employer’s Exhibits 4 at 7 (emphasis added), 10 at 63-70.

The ALJ credited the opinions of Drs. Forehand and Green because they meaningfully considered both of Claimant’s principal pulmonary risk factors—his fifty pack-year smoking history and thirteen-year history of occupational coal mine dust exposure—and explained why coal dust exposure significantly contributed to his obstructive lung disease. Decision and Order at 31-32. Although the ALJ recognized that Claimant’s smoking history was longer than his coal mine employment history, she found Drs. Forehand and Green persuasively explained that coal mine dust exposure remained a

3 significant and additive contributor to his impairment.3 Id. She further found their opinions consistent with “the prevailing view of the medical community that the risks of smoking and coal mine dust exposure are additive.” Id. at 32.

By contrast, the ALJ found Dr. Basheda’s opinion equivocal and inadequately reasoned because he stated he could not determine the cause or severity of Claimant’s impairment without aggressive asthma treatment and follow-up testing, yet also definitively opined that Claimant’s obstructive disease was unrelated to coal mine dust exposure. Decision and Order at 31; Director’s Exhibit 18 at 14-16. She found Dr. Zaldivar’s diagnosis of no pulmonary impairment inconsistent with her finding that Claimant established a totally disabling respiratory or pulmonary impairment – which, as discussed below, we affirm. Decision and Order at 30. Further, she found that, to the extent Dr. Zaldivar recognized obstructive dysfunction, his reliance on the presence and location of Claimant’s radiographic lung abnormalities did not adequately explain his conclusion that Claimant’s obstruction is unrelated to coal mine dust exposure. Id. at 31. She also stated that, even if Drs. Zaldivar and Basheda “are correct that Claimant’s smoking history and obesity are causes of his respiratory symptoms, neither [one] sufficiently explained why Claimant’s occupational exposure to coal mine dust could not also have contributed to his pulmonary impairment.” Id. (emphasis in original) (citing Crockett Colleries, Inc. v. Barrett, 478 F.3d 350 (6th Cir. 2007) (it is proper to assign less weight to a physician who has not adequately explained why he believed coal dust exposure did not contribute to a miner’s respiratory or pulmonary impairment)).

Employer argues the ALJ improperly shifted the burden of proof by requiring Drs.
Basheda and Zaldivar to rule out coal mine dust exposure as a cause of Claimant’s obstructive impairment. Employer’s Brief at 34-35. We disagree. The ALJ did not find legal pneumoconiosis merely because Employer’s physicians failed to disprove that Claimant’s obstruction constitutes legal pneumoconiosis. Rather, she credited the affirmative opinions of Drs. Forehand and Green because she found they meaningfully considered Claimant’s smoking and occupational exposure histories and “credibly

3
The ALJ observed that Dr. Forehand emphasized Claimant’s obstructive lung disease is “a direct result of his inhalation of mixed coal mine dust on a regular basis for 13 years without the benefit of dust mask protection at the face of underground coal mines where dust levels are highest and most toxic.” Decision and Order at 29 (quoting Director’s Exhibit 15 at 5). She further observed Dr. Green explained that Claimant’s greater smoking history “does not diminish the significance of [Claimant]’s 13-year occupational history of exposure to respirable coal and rock dust as an additive, substantial contributing factor to the legal diagnosis of coal workers’ pneumoconiosis.” Id. (quoting Claimant’s Exhibit 5 at 6-7).

4 explained” that both smoking and coal mine dust exposure significantly contributed to his obstructive pulmonary disease. Decision and Order at 31-32. She further evaluated whether Drs. Basheda and Zaldivar adequately explained their contrary opinions attributing Claimant’s obstruction exclusively to nonoccupational causes. Id. at 30-31. An ALJ may consider whether a physician who attributes a pulmonary impairment solely to nonoccupational causes has adequately explained why coal mine dust exposure did not also contribute to the disease. See Harman Mining Co. v. Director, OWCP [Looney], 678 F.3d 305, 313-14 (4th Cir. 2012).

We also reject Employer’s contention that the ALJ impermissibly substituted her medical judgment for that of the physicians by characterizing Drs. Forehand’s and Green’s opinions as “more persuasive and realistic.” Employer’s Brief at 35. Read in context, the ALJ did not independently interpret the objective medical evidence or render her own medical diagnosis. Rather, she compared the physicians’ competing explanations for the cause of Claimant’s obstructive disease and permissibly found the dual-causation opinions of Drs. Forehand and Green more persuasive than the exclusive-causation opinions of Drs. Basheda and Zaldivar. See Extra Energy, Inc. v. Lawson, 140 F.4th 138, 148 (4th Cir. 2025) (ALJ may “permissibly [find] the legal pneumoconiosis opinions of the various physicians to be more or less persuasive than others for a variety of reasons”) (citation modified); Piney Mountain Coal Co. v. Mays, 176 F.3d 753, 756 (4th Cir. 1999); Underwood v. Elkay Mining, Inc., 105 F.3d 946, 949 (4th Cir. 1997); Decision and Order at 30-32. Her observation that Drs. Forehand’s and Green’s opinions are consistent with the accepted medical view that smoking and coal mine dust exposure may have additive effects permissibly bolstered—rather than substituted for—their miner-specific causation reasoning. See Lawson, 140 F.4th at 150.

Employer’s arguments on legal pneumoconiosis are a request to reweigh the evidence, which we are not empowered to do. Anderson, 12 BLR at 1-113. As the ALJ permissibly evaluated the documentation and reasoning underlying the conflicting medical opinions and explained why she found the opinions of Drs. Forehand and Green more persuasive than those of Drs. Basheda and Zaldivar, we affirm her finding that Claimant established legal pneumoconiosis by a preponderance of the medical opinion evidence.4 20 C.F.R. §§718.201(a)(2), (b), 718.202(a)(4); see Looney, 678 F.3d at 313-14.

4
The ALJ correctly found it unnecessary to separately determine the etiology of Claimant’s established legal pneumoconiosis under 20 C.F.R. §718.203. Extra Energy, Inc. v. Lawson, 140 F.4th 138, 145 (4th Cir. 2025) (“Because by definition, legal pneumoconiosis arises out of coal mine employment, a diagnosis of legal pneumoconiosis automatically satisfies the causal requirement between coal mine employment and the 5
Total Disability

A claimant may establish total disability based on qualifying pulmonary function studies or arterial blood gas studies,5 evidence of pneumoconiosis and cor pulmonale with right-sided congestive heart failure, or medical opinions. 20 C.F.R. §718.204(b)(2)(i)-(iv). The ALJ must weigh all relevant supporting evidence against all relevant contrary evidence. See Defore v. Ala. By-Products Corp., 12 BLR 1-27, 1-28-29 (1988); Rafferty v. Jones & Laughlin Steel Corp., 9 BLR 1-231, 1-232 (1987); Shedlock v. Bethlehem Mines Corp., 9 BLR 1-195, 1-198 (1986), aff’d on recon., 9 BLR 1-236 (1987) (en banc). The ALJ found Claimant’s usual coal mine work as a mobile equipment operator required heavy labor6 and that Claimant established total disability based on the blood gas studies, medical opinions, and the evidence as a whole.7 20 C.F.R. §718.204(b)(2)(ii), (iv); Decision and Order at 5, 9-19. Employer contends the ALJ erred in finding Claimant disabled.8 Employer’s Brief at 7-19. We disagree.

Arterial Blood Gas Study Evidence

The ALJ considered three blood gas studies pursuant to 20 C.F.R.
§718.204(b)(2)(ii). Decision and Order at 10-11. Claimant’s May 5, 2020 study produced nonqualifying values at rest and produced a PCO2 value of 49.4 and a PO2 value of 65 with exercise, which the ALJ found is qualifying. Id. at 10; Director’s Exhibit 15.

impairment.”) (citation modified); 20 C.F.R. §§718.201(a)(2), (b), 718.203; Decision and Order at 33.
5
A “qualifying” pulmonary function study or blood gas study yields results equal to or less than the applicable table values in Appendices B and C of 20 C.F.R. Part 718, respectively. A “non-qualifying” study yields results exceeding those values. See 20 C.F.R. §718.204(b)(2)(i), (ii).
6
The ALJ found Claimant’s work as a mobile equipment operator required him to lift and carry between three pounds and 100 pounds several times per day. Decision and Order at 5; Director’s Exhibit 6 at 1.
7
The ALJ found Claimant did not establish total disability based on the pulmonary function studies, and there is no evidence of cor pulmonale with right-sided congestive heart failure. 20 C.F.R. §718.204(b)(2)(i), (iii); Decision and Order at 7-9.
8
We affirm, as unchallenged, the ALJ’s finding that Claimant’s usual coal mine work required heavy labor. See Skrack v. Island Creek Coal Co., 6 BLR 1-710, 1-711 (1983); Decision and Order at 5.

6
Claimant’s January 28, 2022 and September 6, 2022 resting blood gas studies were nonqualifying and no exercise study was administered due to medical contraindication. Director’s Exhibit 18; Employer’s Exhibit 7. Because Claimant’s usual coal mine work required heavy labor, the ALJ credited the May 2020 exercise test over the nonqualifying resting studies to conclude the arterial blood gas studies, considered alone, support a finding of total disability. Decision and Order at 11.

Employer initially asserts the ALJ misinterpreted the results of Claimant’s May 5, 2020 blood gas study and thus erred in determining that it was qualifying. Employer’s Brief at 7-11. The table at 20 C.F.R. Part 718, Appendix C (1), states that for a PCO2 value from 40-49, a PO2 value “equal to or less than” 60 will be qualifying, and that for a PCO2 value “Above 50,” any PO2 value will be qualifying. Further, it is well established that blood gas study values may not be rounded up or down. See Gutierrez v. Califano, 612 F.2d 1247, 1249 (10th Cir. 1979) (Appendix C table values are regulatory boundaries defining qualifying ranges; rounding is impermissible); Tucker v. Director, OWCP, 10 BLR 1-35, 1-41 (1987) (recorded PCO2 and PO2 values must be “equal to or less than” the applicable table values in Appendix C). Employer therefore argues that the ALJ erred in rounding Claimant’s May 5, 2020 PCO2 value of 49.4 to “above 50” to find Claimant’s associated PO2 value of 65 qualifying. Employer’s Brief at 6-8.

We reject Employer’s argument. When the Department introduced the current blood gas tables in Appendix C, it intended for any blood gas studies that produce PCO2 values of 50 or above—not “Above 50”—to be automatically qualifying. See 45 Fed. Reg. 13,678, 13,711 (Feb. 29, 1980) (“The Department has thus decided to adopt a value of 50 mm Hg pCO2 in order to establish disability independent of the pO2.”). Further, contrary to Employer’s contention, the May 5, 2020 study cannot be analyzed using the line on the table for PCO2 values from 40 to 49 because Claimant’s measured PCO2 value of 49.4 is not “equal to or less than” 49. Thus, the study must be analyzed using the next line, for PCO2 values “Above 50” — which effectively means “50 and above.”9 20 C.F.R. Part 718, App. C (1); see Jackson v. Drummond Co., BRB No. 16-0250 BLA, 2017 WL 1103807, at *5 (2017) (unpub.).

Reading Appendix C otherwise would leave recorded PCO2 values greater than 49 but less than 50 without any applicable table value, even though the regulation requires the measured values to be compared against the Appendix C table. We decline to interpret the regulation in a manner that creates such a gap where the regulatory text and history

9
Contrary to Employer’s contention, this conclusion does not rest on deference to an agency interpretation of the regulation, but on the text and structure of Appendix C, read in light of its regulatory history.

7 demonstrate none was intended. See Griffin v. Oceanic Contractors, Inc., 458 U.S. 564, 575 (1982) (noting that “interpretations of a statute which would produce absurd results are to be avoided if alternative interpretations consistent with the legislative purpose are available”); U.S. Steel Mining Co. v. Director, OWCP [Starks], 719 F.3d 1275, 1281-82 (11th Cir. 2013). Because the applicable Appendix C row provides that any corresponding PO2 value is qualifying, Claimant’s exercise PO2 value of 65 is qualifying. 20 C.F.R. Part 718, App. C (1). This conclusion is not the result from rounding Claimant’s measured PCO2 or PO2 values, but from applying the Appendix C row corresponding to his recorded PCO2 value. Therefore, we affirm the ALJ’s finding that the May 5, 2020 blood gas study is qualifying.

Employer next argues the ALJ erred in relying on the May 5, 2020 exercise blood gas study because Drs. Basheda and Zaldivar opined the study should not have been performed due to difficulty walking and safety concerns. Employer’s Brief at 11-12. We reject this argument. Employer identifies no evidence suggesting that the May 5, 2020 exercise study is technically invalid.10 See 20 C.F.R. §718.105(b) (If the results of the blood gas study at rest are nonqualifying, “an exercise blood-gas test shall be offered to the miner unless medically contraindicated.”). The ALJ therefore permissibly considered the exercise study. Because Claimant’s May 5, 2020 exercise study is the only exercise study of record and Claimant’s usual coal mine employment required heavy labor, the ALJ rationally accorded it greater probative weight than the later resting studies.11 See Coen v. Director, OWCP, 7 BLR 1-30, 1-31-32 (1984); Sturnick v. Consolidation Coal Co., 2 BLR 1-972, 1-977 (1980). As Employer raises no further challenge to the ALJ’s weighing of the blood gas evidence, we affirm her finding that Claimant established total disability at 20 C.F.R. §718.204(b)(2)(ii).

Medical Opinions

The ALJ considered the medical opinions of Drs. Forehand and Green, diagnosing total respiratory disability, and those of Drs. Basheda and Zaldivar, opining that Claimant

10
A review of Employer’s closing brief to the ALJ does not disclose any argument that the May 5, 2020 blood gas study should be found invalid or unreliable. Employer’s Closing Brief at 8-9.
11
The ALJ recognized that exercise blood gas testing was medically contraindicated when Drs. Basheda and Gaziano examined Claimant in 2022 and therefore did not discredit those later resting studies. Decision and Order at 11.

8 is not totally disabled.12 Decision and Order at 11-15. Based on the nonqualifying pulmonary function study and qualifying exercise blood gas study that he obtained, Dr. Forehand explained that “[a]n FEV1 of 45% and a pO2 of 65 leave [Claimant] with insufficient ‘wind’ (the ability to increase ventilation in response to an increase in physical activity) and oxygen to return to, meet the physical demands of, or tolerate additional coal mine dust exposure at his last coal mining job.” Director’s Exhibit 15 at 5. Similarly, based on Claimant’s nonqualifying pulmonary function studies demonstrating “significant airflow obstruction and compromise in ventilatory function,” and Dr. Forehand’s May 2020 qualifying exercise blood gas study demonstrating “exercise-induced hypoxemia,” Dr. Green opined Claimant could not perform the heavy labor of his last coal mine work. Claimant’s Exhibits 8 at 4, 10 at 2.

By contrast, based on the nonqualifying pulmonary function test results that he administered, Dr. Basheda diagnosed COPD and a Class II impairment; he opined Claimant’s impairment would not prevent him from returning to his usual coal mine employment but that Claimant “would have difficulty with exertional work such as shoveling coal or carry[ing] heavy objects.” Director’s Exhibit 18 at 15-16. Similarly, after reviewing the objective testing, including Dr. Basheda’s pulmonary function study and Dr. Forehand’s exercise blood gas study, Dr. Zaldivar opined Claimant’s pulmonary function reflected only “mild” obstruction and that the exercise blood gas study did not demonstrate a disabling pulmonary impairment because the A-a gradient was normal. He therefore concluded Claimant is fully capable of performing his usual coal mine employment from a pulmonary standpoint. Employer’s Exhibits 4 at 7, 10 at 55-62.

The ALJ found the opinions of Drs. Forehand and Green well-documented and reasoned because they explained how Claimant’s objective testing—both his pulmonary function study and blood gas study—demonstrated a respiratory impairment that would preclude the heavy exertional requirements of his usual coal mine employment. Decision and Order at 16-17. She accorded less weight to Dr. Basheda’s opinion, finding it inconsistent with the doctor’s acknowledgment that Claimant would have difficulty performing the heavy exertional tasks required by his usual coal mine work. Id. at 17-18. She also accorded less weight to Dr. Zaldivar’s opinion, finding it inadequately explained and inconsistent with the objective evidence she credited, including the qualifying exercise blood gas study. Id. at 18. Consequently, the ALJ found the opinions of Drs. Green and

12
Drs. Forehand and Basheda conducted pulmonary evaluations of Claimant.
Director’s Exhibits 15, 18; Employer’s Exhibit 9. Drs. Basheda, Green, and Zaldivar conducted medical records reviews in offering their disability opinions. Claimant’s Exhibits 5, 8, 10; Employer’s Exhibits 4, 9, 10.

9
Forehand outweighed the contrary opinions of Drs. Basheda and Zaldivar and established total disability pursuant to Section 718.204(b)(2)(iv). Id.

Employer challenges the ALJ’s weighing of the medical opinion evidence, asserting she erred in crediting Dr. Forehand’s opinion and in discrediting the opinions of Drs. Basheda and Zaldivar. Employer’s Brief at 12-19. We reject these arguments.

We first reject Employer’s contention that the ALJ’s alleged errors regarding the May 5, 2020 exercise blood gas study tainted her evaluation of the medical opinion evidence. Because Employer has not established any error in the ALJ’s consideration of that study, its derivative argument necessarily fails. Employer’s Brief at 13. Moreover, as we summarized above, the ALJ credited Drs. Forehand’s and Green’s opinions that a different test—Claimant’s pulmonary function study—also reflects an impairment that prevents him from performing the heavy labor required by his usual coal mine work. Decision and Order at 16-17.

We additionally reject Employer’s assertion that Dr. Forehand’s opinion is unreasoned or undocumented merely because he did not review the entire medical record before rendering his opinion. An ALJ is not required to discredit a physician who did not review all of the medical evidence in the record when the opinion is otherwise well reasoned, documented, and based on the physician’s own examination, objective testing, and relevant occupational, smoking, and medical histories. See Smith v. Kelly’s Creek Res., 26 BLR 1-15, 1-28 (2023); Church v. E. Associated Coal Corp., 20 BLR 1-8, 1-13 (1996).

Nor are we persuaded by Employer’s contention that the ALJ’s analysis is internally inconsistent because she credited Dr. Forehand’s opinion on total disability while according less weight to his opinion on clinical pneumoconiosis.13 Employer’s Brief at 13-

15. An ALJ is not required to completely discredit a physician’s opinion merely because
    one aspect of the opinion is weakened by incomplete or inaccurate information. See Huscoal, Inc. v. Director, OWCP [Clemons], 48 F.4th 480, 491-92 (6th Cir. 2022); Jericol Mining, Inc. v. Napier, 301 F.3d 703, 713 (6th Cir. 2002).

    Regardless the ALJ gave different reasons for crediting Dr. Forehand as to total
    disability but not clinical pneumoconiosis. She permissibly credited Dr. Forehand’s opinion on total disability because it was supported by the objective testing he personally administered and by his explanation of Claimant’s inability to perform the heavy exertional requirements of his usual coal mine employment. See Island Creek Coal Co. v. Compton, 211 F.3d 203, 207-08 (4th Cir. 2000); Lane v. Union Carbide Corp., 105 F.3d 166, 172

    13
    “Clinical pneumoconiosis” consists of those diseases recognized by the medical
    community as pneumoconioses. 20 C.F.R. §718.201(a)(1).

                                        10
    

    (4th Cir. 1997); Eagle v. Armco, Inc., 943 F.2d 509, 512-13 (4th Cir. 1991); Walker v. Director, OWCP, 927 F.2d 181, 184 (4th Cir. 1991); Decision and Order at 16-17. She later accorded less weight to his opinion on a different element of entitlement—clinical pneumoconiosis—because the doctor based his diagnosis on a single chest x-ray and did not account for the subsequently developed radiographic evidence. Decision and Order at
    26. As we are able to understand what the ALJ did and why she did it, she has adequately
    explained her determination as the Administrative Procedure Act (APA) requires. 5 U.S.C.
    §557(c)(3)(A), as incorporated into the Act by 30 U.S.C. §932(a); Wojtowicz v. Duquesne Light Co., 12 BLR 1-162, 1-165 (1989).14 We therefore affirm her determination to credit Dr. Forehand’s total disability opinion as reasoned and documented. See Milburn Colliery Co. v. Hicks, 138 F.3d 524, 533 (4th Cir. 1998); Sterling Smokeless Coal Co. v. Akers, 131 F.3d 438, 441-42 (4th Cir. 1997).

    We additionally reject, as a mischaracterization of the ALJ’s reasoning, Employer’s
    assertion that the ALJ erred in discrediting Dr. Basheda’s opinion for misunderstanding the exertional demands of Claimant’s usual coal mine work. Employer’s Brief at 15-16. Contrary to Employer’s assertion, the ALJ expressly recognized that Dr. Basheda understood Claimant’s coal mine work required him “to lift and carried [sic] 150 pounds.” Decision and Order at 13. In stating “Dr. Basheda’s opinion is contrary to my finding that Claimant’s work required heavy exertion,” the ALJ was not referring to Dr. Basheda’s understanding of Claimant’s job duties. Id. at 17 (emphasis in original). Rather, it was Dr. Basheda’s opinion that Claimant could perform his usual coal mine employment but “would have difficulty with very exertional work such as shoveling coal or carrying heavy objects” that the ALJ found inconsistent with her finding that Claimant’s usual coal mine employment required heavy exertion. Id. (citing Director’s Exhibit 18 at 14-16). In assessing the credibility of Dr. Basheda’s opinion, the ALJ permissibly compared his assessment of Claimant’s physical limitations with the exertional requirements of Claimant’s usual coal mine employment. See Budash v. Bethlehem Mines Corp., 9 BLR 1-48, 1-51-52 (1986) (en banc).

    We also reject Employer’s assertions of error regarding the ALJ’s determination to
    discount Dr. Zaldivar’s opinion. The ALJ permissibly discounted Dr. Zaldivar’s opinion because he rejected the qualifying May 5, 2020 exercise blood gas study based upon his calculation of Claimant’s A-a gradient rather than the disability criteria set forth in Appendix C. Decision and Order at 11 n.10, 18. Employer does not challenge the ALJ’s determination that reliance on the A-a gradient, rather than the regulatory standards

    14
    The APA requires every adjudicatory decision “include a statement of . . . findings
    and conclusions, and the reasons or basis therefor, on all the material issues of fact, law, or discretion presented on the record.” 5 U.S.C. §557(c)(3)(A).

                                          11
    

    governing arterial blood gas studies, undermined the credibility of Dr. Zaldivar’s disability assessment. We therefore affirm the ALJ’s decision to accord his opinion less weight.15 See Compton, 211 F.3d at 211; Grizzle v. Pickands Mather & Co., 994 F.2d 1093, 1096 (4th Cir. 1993).

    As the ALJ provided valid reasons for her credibility determinations, we affirm her
    determination to credit the disability opinions of Drs. Forehand and Green over those of Drs. Basheda and Zaldivar to find Claimant established total disability by a preponderance of the medical opinions. 20 C.F.R. §718.204(b)(2)(iv). As Employer raises no further challenge to the ALJ’s consideration of the evidence at 20 C.F.R. §718.204(b)(2), we affirm the ALJ’s finding that Claimant established total disability based on the record as a whole. See Defore, 12 BLR at 1-28-29; Rafferty, 9 BLR at 1-232; Shedlock, 9 BLR at 1- 198.

                               Disability Causation
    

    To establish disability causation, Claimant must prove that pneumoconiosis is a
    “substantially contributing cause” of his totally disabling respiratory or pulmonary impairment. 20 C.F.R. §718.204(c)(1); Cedar Coal Co. v. Director, OWCP [Mullins], 168 F.4th 685, 689 (4th Cir. 2026). Pneumoconiosis is a substantially contributing cause if it has “a material adverse effect on the miner’s respiratory or pulmonary condition,” or if it “[m]aterially worsens a totally disabling respiratory or pulmonary impairment which is caused by a disease or exposure unrelated to coal mine employment.” 20 C.F.R.

    15
    Employer’s challenges to Dr. Zaldivar’s opinion—that the ALJ improperly found
    Dr. Zaldivar conflated total disability with legal pneumoconiosis and improperly relied upon his discussion of Dr. Werchowski’s pulmonary function study—mischaracterize the ALJ’s decision. Employer’s Brief at 16-19. The ALJ did not find Dr. Zaldivar conflated total disability with legal pneumoconiosis; rather, she found he conflated the existence of a disabling respiratory impairment with its cause. Decision and Order at 18. Likewise, the ALJ did not discount Dr. Zaldivar because he considered Dr. Werchowski’s pulmonary function study valid. Instead, she observed that Dr. Zaldivar simultaneously accepted the study as valid and acknowledged it demonstrated an inability to perform Claimant’s usual coal mine employment, while elsewhere discounting its significance because it was administered shortly after Claimant’s acute respiratory illness. Id. at 14 n.19, 18. Because the ALJ provided an independent, valid basis for according less weight to Dr. Zaldivar’s opinion—his reliance on the A-a gradient—we need not further address Employer’s remaining challenges to the ALJ’s alternative observations regarding his opinion. See Kozele v. Rochester & Pittsburgh Coal Co., 6 BLR 1-378, 1-382 n.4 (1983).

                                         12
    

    §718.204(c)(1)(i), (ii); see Robinson v. Pickands Mather & Co., 914 F.2d 35, 37-38 (4th Cir. 1990).

    The ALJ considered the causation opinions of Drs. Forehand, Green, Zaldivar, and
    Basheda. Decision and Order at 33-36. Dr. Green explicitly attributed Claimant’s disabling respiratory impairment, in part, to Claimant’s legal pneumoconiosis in the form of COPD, while Dr. Forehand diagnosed a disabling respiratory impairment due to “coal workers’ pneumoconiosis with impairment of gas exchange,” and “obstructive lung disease” due, in part, to coal dust exposure. Director’s Exhibit 15 at 5; Claimant’s Exhibit 5 at 10-11. Although Drs. Basheda and Zaldivar did not diagnose either pneumoconiosis or a totally disabling respiratory or pulmonary impairment, they nonetheless excluded pneumoconiosis as a cause of Claimant’s impairment. Decision and Order at 34-35; Director’s Exhibit 18 at 15-16; Employer’s Exhibits 4 at 6-7, 9 at 35-39, 10 at 67-70.

    The ALJ inferred Dr. Forehand diagnosed total disability due to legal
    pneumoconiosis but found his opinion merits reduced probative weight because it is “not particularly well explained.” Decision and Order at 33-34. She found Dr. Green’s opinion well documented and reasoned because he considered the relevant medical literature and evidence of record and persuasively explained how Claimant’s legal pneumoconiosis materially contributes to his disability. Id. at 35-36. By contrast, she found the opinions of Drs. Basheda and Zaldivar inextricably intertwined with their failure to diagnose legal pneumoconiosis (and failure to diagnose a totally disabling respiratory or pulmonary impairment), and therefore unpersuasive as to whether legal pneumoconiosis contributed to Claimant’s total respiratory disability. Id. at 34-35. Primarily crediting Dr. Green’s opinion, as supported by Dr. Forehand’s opinion, the ALJ found Claimant established total disability due to legal pneumoconiosis. Id. at 36.

    Employer raises no independent challenge to the ALJ’s disability causation finding
    apart from its challenges to her findings of legal pneumoconiosis and total disability. Further, we see no error in the ALJ’s determination to discount the opinions of Drs. Basheda and Zaldivar because they did not diagnose pneumoconiosis, contrary to her finding that Claimant established the disease. See Mullins, 168 F.4th at 693; Hobet Mining, LLC v. Epling, 783 F.3d 498, 504-05 (4th Cir. 2015); Scott v. Mason Coal Co., 289 F.3d 263, 269-70 (4th Cir. 2002); Toler v. E. Associated Coal Co., 43 F.3d 109, 116 (4th Cir. 1995). Similarly, as the only evidence that may be given substantial weight indicates legal pneumoconiosis is the cause of Claimant’s disability, we see no error in the ALJ’s determination to credit the disability causation opinions of Drs. Green and Forehand. See Scott, 289 F.3d at 270. We therefore affirm that Claimant established total disability due to legal pneumoconiosis.

                                        13
    

    As Claimant has established each element of entitlement, we affirm the ALJ’s award
    of benefits.16 Anderson, 12 BLR at 1-112; Trent, 11 BLR at 1-27.

    Accordingly, we affirm the ALJ’s Decision and Order Awarding Benefits.

    SO ORDERED.

                                     JONATHAN ROLFE, Acting Chief
                                     Administrative Appeals Judge
    
                                     DANIEL T. GRESH
                                     Administrative Appeals Judge
    
                                     GLENN E. ULMER
                                     Administrative Appeals Judge
    

    16
    As Claimant has established his total disability is due to legal pneumoconiosis,
    we need not address Employer’s challenges to the ALJ’s separate finding of clinical pneumoconiosis. Employer’s Brief at 19-35. Any error the ALJ may have made in finding Claimant also established clinical pneumoconiosis is harmless. See Larioni v. Director, OWCP, 6 BLR 1-1276, 1-1278 (1984). Similarly, because we affirm the ALJ’s award on the merits of entitlement under Part 718, we need not address Claimant’s contention that his overtime work should be credited toward establishing fifteen years of qualifying coal mine employment for purposes of invoking the Section 411(c)(4) presumption. Id.; Claimant’s Brief at 4.