Black Diamond Coal Mining Company (“Black Diamond”) appeals the decision of the Benefits Review Board (“BRB”) awarding disability benefits under the Black Lung Benefits Act, 30 U.S.C. §§ 901 to 945 (1994) (“the Act”), and its accompanying regulations. See 20 C.F.R. pt. 718 (1996). The sole issue on appeal is whether Herman Mar-cum’s total pulmonary disability was due to pneumoconiosis. Because the BRB did not apply the proper causation standard, we vacate and remand.
I. Background
Herman Marcum, an Alabama coal miner last employed by Black Diamond, filed a claim for black lung disability benefits on November 25, 1980. The Office of Workers Compensation Programs (“OWCP”) within the Department of Labor made an initial determination that Marcum was entitled to benefits. Black Diamond, the coal mine operator responsible for the payment of Mar-cum’s benefits under the Act, requested a hearing before an Administrative Law Judge (“ALJ”). Herman Marcum died on May 27, 1985, one month before the hearing. He was survived by his wife Edna, who has since prosecuted his claim for benefits, as well as a claim for survivor’s benefits.
At the hearing, evidence was proffered by Marcum, Black Diamond, and the Director of OWCP (“the Director”), who appeared as a party in interest on behalf of Marcum. The evidence included reports and letters from four physicians who examined Herman Mar-cum before his death: Dr. Russakoff, Dr. Shelton, Dr. Branscomb, and Dr. Hood. Dr. Russakoff examined Marcum in January *1081 1991, and concluded that Marcum’s pulmonary disability might be due to his coal mine exposure. Dr. Russakoffs 1981 report was based on the assumption that Marcum did not have a significant smoking history. In a letter written in 1985, Dr. Russakoff admitted that he had overlooked Marcum’s history of bronchial asthma in his 1981 report. Dr. Russakoff concluded in the 1985 letter that, assuming Marcum smoked a pack of cigarettes a day for 28 years, the miner’s lung disease probably had little to do with his coal mine employment. Black Diamond attempted to introduce Dr. Russakoffs 1985 letter at the hearing, but the ALJ excluded it on the grounds that Blaek Diamond failed to give Marcum timely notice of intent to introduce the letter.
Dr. Shelton, who examined Marcum in May 1981, concluded that Marcum’s respiratory difficulty was due to asthma, but that his chest x-rays were consistent with inhalation lung disease. Dr. Branscomb examined Marcum in June 1982, and his medical history of Marcum indicates that Marcum daily smoked a pack of cigarettes from ages 20 to 56. Dr. Branscomb concluded that 30% of Marcum’s pulmonary disability was due to occupational exposure.
Dr. Hood was Marcum’s treating physician from 1980 until his death in 1985. In a letter written shortly after Marcum’s death, Dr. Hood stated that Marcum’s pneumoconiosis, as well as other complications, had rendered the miner totally disabled. Dr. Hood’s letter was excluded by the ALJ on procedural grounds.
The ALJ awarded benefits based in part on the finding that Marcum was totally disabled due to pneumoconiosis. Black Diamond appealed to the Benefits Review Board (“BRB”). The BRB reversed and remanded for reconsideration of several issues, including total disability and causation.
On remand, the ALJ followed
Wilburn v. Director, OWCP,
11 Black Lung Reporter (B.L.R.) 1-135,1-137 (Ben.Rev.Bd.1988), and applied the causation standard that a total pulmonary disability is due to pneumoeonio-sis when the pneumoconiosis, in and of itself, causes the disability. The ALJ denied benefits based on the conclusion that, although Marcum established a total pulmonary disability, he did not establish causation under the
Wilburn
standard. After the ALJ’s decision, this court held in
Lollar v. Alabama By-Products Corp.,
Following the second remand, 1 the ALJ concluded that Marcum failed to show that his pneumoconiosis substantially contributed to his total pulmonary disability. In making this determination, the ALJ relied on Dr. Russakoffs 1985 report and Dr. Hood’s report, which had been marked for identification purposes, but were not formally in the record. Marcum appealed the ALJ’s decision to the BRB. The BRB read Lollar to hold that only a showing that pneumoconiosis played an infinitesimal or de minimis part in the miner’s total pulmonary disability would preclude a finding of causation. The BRB found that the medical evidence in the record satisfied the Lollar standard, and awarded benefits. Blaek Diamond filed this appeal.
II. Jurisdiction
During the pendency of this appeal, the Director filed an Application for an Order to Show Cause why Blaek Diamond’s Petition for Review Should not be Dismissed for Lack of Jurisdiction, which we construe as a motion to dismiss for lack of jurisdiction. The Director states that Black Diamond, formerly an Alabama corporation, has been dissolved, and Blaek Diamond’s benefits trust has been depleted. The Director contends that this appeal is moot because the court is powerless to grant Marcum meaningful relief. If the Director is correct, then we lack jurisdiction to decide this case.
See Pacific Ins. Co. v. General Dev. Corp.,
III. Standard of Review
Whether a miner’s total pulmonary disability is “due to” pneumoconiosis within the meaning of 20 C.F.R. § 718.204 is a mixed question of law and fact. The ALJ’s factual findings are entitled to great deference, and they are to be upheld if they are supported by substantial evidence.
Lollar,
Courts generally owe deference to an agency policymaker’s interpretation of the agency’s own regulation, but neither the AL J nor the BRB functions as a policymaker in this case. See id. at 1262. The ALJ’s and the BRB’s interpretations of the regulations implementing the Act are legal conclusions that we review de novo.
IY. Discussion
To establish eligibility for black lung benefits, a claimant generally must show (1) that the miner has pneumoconiosis, (2) that the pneumoconiosis arose from the miner’s coal mine employment, (3) that the miner has a total pulmonary disability, and (4) that the total pulmonary disability is due to pneumoconiosis.
Lollar,
The third and fourth requirements for eligibility arise from 20 C.F.R. § 718.204, which states: “Benefits are provided under the Act for or on behalf of miners who are totally disabled due to pneumoconiosis_” Section 718.204 establishes standards for a claimant to show the existence of a total pulmonary disability,
3
but the regulation is less clear about when a total disability is “due to” pneumoconiosis.
See id.
As a result of the regulation’s ambiguity, problems arose in cases, like
Lollar,
where the miner’s medical history suggested several potential causes for the pulmonary disability. For example, in addition to pneumoconiosis, Lol-lar suffered from interstitial lung disease and chrome bronchitis.
Lollar,
This court addressed the “due to” causation standard of § 718.204 for the first time in
Lollar.
The
Lollar
court was persuaded by decisions in three other circuits that the
Wilburn
rule that pneumoconiosis must “in and of itself’ cause the pulmonary disability was “unduly stringent.”
Id.
at 1265;
see Mangus v. Director, OWCP,
In defining the “due to” causation test of § 718.204, the
Mangus, Bonessa,
and
Adams
*1083
courts phrased the applicable test differently.
See Mangus,
[T]he Sixth Circuit in Adams, while not using the terms “substantial” or “significant” in its standard, was careful to observe that “nothing in this record suggests that Adams’ pneumoconiosis played only an infinitesimal or de minim[i]s part in his totally disabling respiratory impairment, so we need not consider here whether such a finding ... would support a denial of benefits under the Act.” We believe Bonessa’s phrasing of the test answers this concern.
Id. (quoting Adams, 886 F.2d at 826 n. 11) (alteration in original).
Both the ALJ and the BRB purported to apply
Lollar'
s substantial contributing cause test to Marcum’s claim. Although the parties agree that the
Lollar
causation standard applies, we note that the holding in
Lollar
does not, on its face, apply to Marcum’s claim. The
Lollar
court held that the substantial contributing factor standard applies to black lung benefits claims filed after January 1, 1982,
Lollar,
Marcum did not have fifteen years of underground coal mine employment, and thus did not qualify for the § 718.305 presumption. We hold that black lung claimants who file before January 1, 1982 and are not entitled to the § 718.305 presumption must satisfy the Lollar causation standard in order to qualify for benefits under § 718.204.
Black Diamond argues that the BRB misapplied the Lollar standard, and we agree. Although the BRB quoted Lollar as requiring pneumoconiosis to be a “substantially contributing cause,” the BRB also read Lol-lar to hold that:
only a physician’s medical opinion concluding that the miner’s pneumoconiosis “ ‘played only an infinitesimal or de minim[i]s part in his totally disabling respiratory impairment,’ ” would be insufficient to establish causation pursuant to Section 718.204(b).
Marcum v. Black Diamond Coal Co.,
BRB No. 92-0781 (Jan. 31, 1994) (quoting
Lollar,
Black Diamond argues that the ALJ properly applied the Lollar standard, and that the ALJ’s finding that Marcum did not establish causation is supported by substantial evidence in the record. We agree that the ALJ properly applied the Lollar standard, but disagree that the ALJ’s factual findings are entitled to deference in this case. In determining that Marcum’s pneumoconiosis was not a substantial contributing cause of his total pulmonary disability, the ALJ relied on Dr. Hood’s report, and Dr. Russakoffs 1985 report, which are not part of the record in this case. 4
Because we cannot defer to the ALJ’s findings, we vacate the BRB’s award of bene *1084 fits and remand to the BRB for a determination, consistent with this opinion, of whether Marcum’s total pulmonary disability was due to pneumoconiosis. In answering this question, the substantial contributing cause standard of Lollar applies, and only evidence that is properly in the record should be considered.
VACATED and REMANDED.
Notes
. On both remands, Marcum's case was heard by a different ALJ than the one who conducted the hearing.
. The motion to dismiss is denied.
. Section 718.204 refers to a "total disability" rather than a total pulmonary disability, but it is clear from the criteria for establishing a total disability that only pulmonary disabilities are relevant.
See
20 C.F.R. § 718.204(c) (miner can establish a total disability, in the absence of contrary evidence, by reference to a pulmonary function test or an arterial blood gas test).
See also Lollar,
. Although it is unimportant to the resolution of this appeal, we note that the BRB also considered Dr. Hood’s report in concluding that Mar-cum was entitled to benefits.
