## Facts

- Richard J. Rost worked for three to four months in 1950 at an auto repair shop that primarily serviced Ford vehicles.
- Mechanics regularly performed brake and clutch work on Ford vehicles; the work generated visible dust.
- Rost’s duties included sweeping and cleaning brake and clutch dust, and he wore dust-contaminated clothing home.
- Rost later worked for decades at a power plant with additional significant asbestos exposure from other sources.
- Rost developed mesothelioma years later, consistent with asbestos disease latency.
- Plaintiffs presented expert testimony (Dr. Arthur Frank) stating mesothelioma risk is dose-responsive, that exposures contribute cumulatively to total dose, and that Rost’s Ford-related exposures—considering their conditions and frequency—contributed substantially to his disease.

## Issues

1. Whether the evidence satisfied Pennsylvania’s frequency, regularity, and proximity criteria to permit a jury finding that asbestos from Ford-related friction products was a substantial factor in causing Rost’s mesothelioma.
2. Whether the plaintiffs’ expert causation testimony improperly functioned as an “each and every breath/any exposure” theory barred under Pennsylvania law.
3. Whether the trial court abused its discretion by consolidating Rost’s case with other mesothelioma cases and by denying post-trial relief (JNOV/new trial).

## Decision

- The Supreme Court of Pennsylvania affirmed the judgment for plaintiffs.
- The Court held the evidence and expert testimony were legally sufficient under the frequency-regularity-proximity framework to support substantial-factor causation.
- The Court concluded the expert’s cumulative-dose discussion did not constitute an impermissible “each and every breath” theory because it was part of a case-specific causation analysis tied to Rost’s exposure history.
- The Court found no abuse of discretion in consolidating the trials and no reversible evidentiary or trial-error basis for JNOV or a new trial.

## Legal Principles

- In asbestos product-liability cases, substantial-factor causation generally requires evidence of exposure to a defendant’s product with sufficient frequency, regularity, and proximity to allow a reasoned jury inference of causation.
- The frequency-regularity-proximity criteria are qualitative guides and are applied flexibly, not as rigid or purely quantitative prerequisites.
- Expert testimony is inadmissible if it treats any occupational exposure (or “each and every breath/fiber”) as automatically a substantial factor without a case-specific assessment tied to the plaintiff’s actual exposures.
- An expert may testify that exposures contribute cumulatively to total asbestos dose, so long as the opinion does not substitute “any exposure” for a defendant-specific substantial-factor analysis.
- In multi-source exposure cases, a plaintiff need not prove the defendant’s product was the predominant exposure or exclude all other possible causes; the question is whether the defendant’s product was a substantial factor.

## Conclusion

The court sustained a mesothelioma verdict against Ford where the plaintiff offered evidence of daily, close-range exposure to asbestos-containing brake and clutch dust for several months and expert testimony linking that exposure to disease through a case-specific substantial-factor analysis, while rejecting the view that recognizing cumulative dose equals an impermissible “each and every breath” theory.


Rost v. Ford Motor Co., 151 A.3d 1032 (Pa. 2016)