OPINION OF THE COURT
LARSEN, Justice.The issue before the Court in this products liability case is whether the trial court committed reversible error in instructing the jury that it could apportion damages between defendant-appellees and plaintiff-appellant.
Appellant, Joseph Edward Martin, filed a complaint in trespass on August 16, 1978, against appellees seeking compensatory and punitive damages for asbestosis and related diseases which he claimed were caused as a result of *380working with products containing asbestos manufactured by appellees.1
Appellant presented expert witnesses at trial who testified that his disability was due to both asbestosis, caused by asbestos exposure, and emphysema, caused by appellant’s long-term cigarette smoking and aggravated by asbestos exposure and the resulting asbestosis. Appellees presented expert testimony that appellant’s disability was solely the result of emphysema, caused by cigarette smoking. The trial court instructed the jury on apportionment as follows:
... If, however, you find that his condition is due both to his cigarette smoking and his exposure to asbestos, then you first determine what the total amount of damages are, and then the next thing you do is to determine what percentage of his condition is due to cigarette smoking, and then you will reduce the total amount by the percentage that you find is due to cigarette smoking.
(N.T., Vol. V at 87.) The jury thereafter returned a verdict of $67,000 in favor of appellant,2 although appellant presented testimony that his loss of earnings was greatly in excess of that amount. (N.T. 134-144.)3
The trial court denied appellant’s motions for a new trial. Superior Court, on appeal by appellant and cross-appeal by appellee Combustion Engineering, Inc., reversed on the basis of trial error not relevant here and remanded for a new trial limited to the issue of damages. Martin v. Johns-Manville Corp., 322 Pa.Super. 348, 469 A.2d 655 (1983). This Court granted appellees’ petition for allowance, reversed Superior Court’s order and remanded this case to Superior Court for consideration of the instant apportionment issue, which that Court found unnecessary *381to address earlier. Martin v. Johns-Manville Corp., 508 Pa. 154, 494 A.2d 1088 (1985). On remand, Superior Court rejected appellant’s argument and found that the causes of harm were “distinct and capable of rough approximation,” and affirmed the trial court’s denial of appellant’s motion for a new trial. Martin v. Johns-Manville Corp., 349 Pa.Super. 46, 59, 502 A.2d 1264, 1271 (1985).
We granted appellant’s petition for allowance on July 1, 1986. We now hold that there was no evidence presented at trial upon which the trial court could properly submit the issue of apportionment to the jury. Thus, we reverse Superior Court’s affirmance of the trial court’s denial of a new trial.
We begin our analysis as we did when this case was before this Court previously, by noting our scope of review. “[T]he grant or denial of a new trial will not be reversed on appeal absent either an error of law which controlled the outcome of the case, Anzelone v. Jesperson, 436 Pa. 28, 30, 258 A.2d 510, 510 (1969); Allison v. Snelling & Snelling, Inc., 425 Pa. 519, 521, 229 A.2d 861, 862 (1967), or a palpable abuse of discretion where the ruling turns on the weight of the evidence, Lobozzo v. Adam Eidenmiller, Inc., 437 Pa. 360, 367-68, 263 A.2d 432, 436 (1970).” Martin v. Johns-Manville, supra, 508 Pa. at 163, 494 A.2d at 1083.
The rules in this Commonwealth governing apportionment of damages are consistent with those expressed in the Restatement (Second) of Torts:
§ 433 A. Apportionment of Harm to Causes
(1) Damages for harm are to be apportioned among two or more causes where
(a) there are distinct harms, or
(b) there is a reasonable basis for determining the contribution of each cause to a single harm.
(2) Damages for any other harm cannot be apportioned among two or more causes.
See, e.g., Offensend v. Atlantic Refining Co., 322 Pa. 399, 185 A.2d 745 (1936); McAllister v. Pennsylvania Railroad *382Company, 324 Pa. 65, 187 A. 415 (1936); Embrey v. Borough of West Mifflin, 257 Pa.Super. 168, 390 A.2d 765 (1978). “The rules stated apply also where one of the causes in question is the conduct of the plaintiff himself, whether it be negligent or innocent.” Restatement (Second) of Torts § 433A, comment (a). The trial court must determine, as a matter of law, whether the harm is capable of apportionment, Voyles v. Corwin, 295 Pa.Super. 126, 130, 441 A.2d 381, 383 (1982); Restatement (Second) of Torts § 434(1)(b), and the burden of proving apportionment rests on the party seeking it. Restatement (Second) of Torts § 433B(2).
In this case, § 433A(1)(b) is applicable since the single harm to appellant was his disability due to the decreased function of his lungs. Thus, it was incumbent upon the trial court to determine that there was a reasonable basis for apportioning the harm between the two causes before submitting that issue to the jury. In this regard, the trial court concluded “[t]here was adequate evidence which would support a jury’s determination that the acts of [appellant] and the acts of the [appellees] caused separate and identifiable damages.” (Trial Court Opinion at p. 39.)' We disagree.
Testimony at trial established that appellant worked at various jobs between the years 1939 and 1978, when he became disabled, applying and removing asbestos insulation products to and from pipes and boilers. Also, appellant began smoking cigarettes in 1941, and eventually increased his smoking to two packs a day by 1960. Appellant maintained that level of smoking through 1978. (N.T., Vol. I at 349-50.)
Testimony from appellant’s family doctor was presented by way of deposition concerning appellant’s history of respiratory problems beginning in 1968. (N.T., Vol. III at 171-203.)
Five expert witnesses analyzed x-rays and described in some detail the evidence of both emphysema and asbestosis present in appellant’s lungs. Results of physical examina*383tions given appellant were also discussed at some length. Of the five expert witnesses presented at trial, three were asked if they had opinions concerning the cause of appellant’s disability. Dr. Sachs and Dr. Laman, called on behalf of appellant, each expressed the opinion that asbestos exposure and cigarette smoking were both significant causes of his disability. (N.T., Vol IA at 787, Vol. II at 19.) Dr. Shively, called on behalf of appellees, testified that, in his opinion, appellant’s asbestosis was not very advanced and played no role in appellant’s disability, which he attributed solely to emphysema caused by cigarette smoking. (N.T., Vol. IV at 107.) The jury resolved this dispute in expert testimony in favor of appellant, as evidenced by the verdict, since the trial court properly instructed the jury not to award damages if cigarette smoking was the sole cause of appellant’s disability. (N.T., Vol. V at 86-87.)
Additionally, Dr. Sachs was asked to separate out the relative contributions of each of the diseases to appellant’s disability. Dr. Sachs responded:
I can’t separate these two diseases for you in terms of percentage. My opinion is that both play a significant role in this man’s disability, but I have no way of equating them or breaking them down. I can’t tell you that asbestos contributed 48% and emphysema 52%, I don’t know how to do that. There is no way I know of to separate these two diseases which are so closely intertwined.
I believe that both of them exist to a significant degree and they are both significant factors in this man’s disability. That is the best I can do with that.
(N.T., Vol. IA at 787.)
Dr. Laman testified:
It is not possible for me to separate out the relative contribution of cigarette smoking and asbestos from the cause of his obstructive pulmonary disease and the cause of his total and permanent disability. Both factors are *384important in producing the effect and the pulmonary disability that he has.
(N.T., Vol. IIA at 19.)
Dr. Laman further testified:
It is not possible to separate out what fraction of his lung disease is due to cigarette smoking, what factor, what fraction is due to asbestosis.
(N.T., Vol. IIA at 27.)'
Finally, Dr. Laman stated:
... Both cigarette smoking and asbestos exposure and asbestosis result in obstructive defects on ventilatory testing. Since both testing lead to obstructive defect, it becomes difficult to impossible to accurately ascribe a fraction of the defect due to one thing or the other.
(N.T., Vol. IIA at 27-28.)
The jury, although presented with a great deal of testimony concerning appellant’s history and physical condition, was provided no guidance in determining the relative contributions of asbestos exposure and cigarette smoking to appellant’s disability. In fact, two experts testified that such a determination was not possible. A situation analagous to the instant case arose in Offensend v. Atlantic Refining Co., supra. There, a jury award of damages for aggravation of an existing tubercular condition was modified (reduced), because the expert testimony did not address the duration of the aggravation. “If the doctors were not in a position to make an estimate of the extent of the aggravation in point of time, the jury should not have been allowed to hazard a guess beyond the period shown with reasonable certainty.” Id., 322 Pa. at 404, 185 A.2d 745. Here, as in Offensend, the jury cannot be expected to draw conclusions which medical experts, relying on the same evidence, could not draw. The causes of disability in this case do not lend themselves to separation by lay-persons on any reasonable basis.4 Thus, common sense and common *385experience possessed by a jury do not serve as substitutes for expert guidance, and it follows that any apportionment by the jury in this case was a result of speculation and conjecture and hence, improper.5 “Rough approximation” is no substitute for justice.6
The trial court erred by presenting the issue of apportionment to the jury.7
The trial court’s error resulted in an inadequate verdict in this case, since the jury obviously apportioned to arrive at the verdict of $67,000, which is far below even a conservative estimate of the damages established at trial. See note 3, supra. Where, as here, no challenge is raised regarding liability, and the only trial error involves the issue of damages, the appropriate remedy is a new trial limited to the issue of damages. Troncatti v. Smereczniak, 428 Pa. 7, 10, 235 A.2d 345, 346 (1967). See also, Stokan v. Turnbull, 480 Pa. 71, 389 A.2d 90 (1978); Gagliano v. Ditzler, 437 Pa. 230, 263 A.2d 319 (1970).
Superior Court’s order is reversed. The order of the trial court denying appellant’s motions for a new trial is vacated and the case is remanded to the Court of Common Pleas of Allegheny County for a new trial limited to the issue of damages.
*386McDERMOTT, J., filed a concurring opinion. NIX, C.J., filed a dissenting opinion joined by ZAPPALA, J. HUTCHINSON, J., filed a dissenting opinion.. Joseph Edward Martin died on August 1, 1982 while post-trial motions were pending.
. Appellant’s claim for punitive damages was not presented to the jury.
. Appellant asserts he established loss of earnings of at least $177,000. Superior Court estimated the amount at $118,000. In any event, the verdict was far below the loss of earnings established by appellant at trial.
. Compare, McAllister v. Pennsylvania Railroad Co., supra. (Medical testimony and other proofs made it possible for jury to arrive at a reasonable basis of apportionment), with Capone v. Donovan, 332 *385Pa.Super. 185, 480 A.2d 1249 (1984). (Apportionment on reasonable basis not possible where three physicians each failed to properly diagnose fracture of plaintiffs arm.)
. Rice v. Hill, 315 Pa. 166, 173, 172 A. 289, 291-92 (1934). (A jury may not award damages based upon speculation or conjecture.)
. As stated by Dean Prosser and Dean Keeton:
Certain results, by their very nature, are obviously incapable of any reasonable or practical division ... no ingenuity can suggest anything more than a purely arbitrary apportionment of such harm. Where two or more causes combine to produce such a single result, incapable of any reasonable division, each may be a substantial factor in bringing about the loss, and if so, each is charged with all of it.
Prosser and Keeton on Torts § 52 at p. 347 (5th Ed. 1984).
. Thus, it is unnecessary to address appellant’s remaining claims which challenge the sufficiency of the trial court’s instructions on apportionment.