Industrial hygienist (exposure reconstruction)
Expert class library · Environmental and toxic tort · Either side
An industrial hygienist who reconstructs how much asbestos, silica, benzene, diesel exhaust or other substance a worker or household member breathed over years, so that a causation expert has a dose to work with. Because measurements from the actual workplace rarely exist, the hygienist builds the estimate from co-worker testimony, studies of similar jobs and modeling. Courts increasingly treat gaps in that foundation as matters for cross-examination, but they exclude estimates that rest on an inapt study, an unsupported respirator protection factor or a conversion the literature does not recognize.
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What this expert is retained to answer
- What measurements or studies support the exposure levels, and how closely do they match this worker's tasks, materials and era?
- Which respirator or control protection factor did the expert apply, and is it supported by an assigned protection factor or published data?
- Did the expert use maximum, mean or median concentrations, and why?
- Does the expert rely on the worker's own account and co-worker testimony, and is that enough for the jurisdiction's standard?
- How does the dose estimate connect to the epidemiology the causation expert relies on?
Methods
- Task-based exposure reconstruction from work history and co-worker testimony
- Use of published exposure studies and historical air monitoring
- Respirator and engineering-control protection factors
- Exposure modeling and job-exposure matrices
- Cumulative dose calculation against exposure limits and background
How the testimony is attacked
- Unsupported protection factor. A dose that depends on how much a respirator protected the worker needs a sourced protection factor. In Cole v. Exxon Mobil the Texas Court of Appeals affirmed excluding a hygienist's olivine dose calculation that used a protection factor from an old study of different hoods and the maximum measured concentration.
- Foundation built on the worker's account. Defendants argue an estimate built from interviews and depositions lacks sufficient facts. In Molitor v. BNSF Railway the Illinois Appellate Court reversed the exclusion of a hygienist's diesel exhaust and herbicide opinions, holding that methodology was generally accepted and foundation questions went to weight.
- Insufficient facts and data. The Louisiana Fourth Circuit in Craft v. Eagle reversed an order confining an industrial hygienist to general opinions, holding that the evidence behind his case-specific exposure estimates affected weight, not admissibility.
- Unrecognized conversions and tools. Opponents attack conversions between exposure measures and risk tools designed for other settings. In Lewis v. Norfolk Southern Railway the Florida Fifth District reversed an exclusion based on such criticisms, holding the expert's diesel exposure methodology satisfied Daubert.
- Above background is not a dose. Testimony that exposure was above background, without an estimate of how much, is attacked as insufficient for causation in jurisdictions that require a quantified dose.
What the public record shows
Courts have filed at least 53 opinions since 2015 that address this class of testimony under Daubert or Rule 702, as of October 4, 2026. 4 rulings that show how courts handle this class of testimony:
| Outcome | Case | Court | Year | Why |
|---|---|---|---|---|
| Exclusion reversed | Lewis v. Norfolk Southern Railway Co.No. 5D2024-1567 | Fla. Dist. Ct. App. | 2025 | The court reversed summary judgment for a railroad, holding the trial court erred in excluding the liability expert's opinion that a former engineer had long-term, above-background exposure to diesel exhaust and benzene, which the trial court had found unreliable for converting elemental carbon measurements to diesel particulate and using an EPA risk tool. |
| Excluded | Cole v. Exxon Mobil Corp.No. 14-22-00756-CV | Tex. App. | 2024 | The court affirmed excluding an industrial hygiene expert's dose calculations for an abrasive blaster's olivine, nickel and chromium exposure, because he applied a respirator protection factor without supporting authority, drawn from a 1975 study of different hoods, and used the maximum measured concentration, rendering the doses unreliable; summary judgment for the premises owner was affirmed over a dissent. |
| Exclusion reversed | Craft v. Eagle, Inc.No. 2024-C-0616 | La. Ct. App. | 2024 | Granting a supervisory writ in a take-home asbestos case, the court reversed an order limiting a certified industrial hygienist to general opinions and barring his estimates of the worker's and his wife's asbestos exposures, holding the evidence underlying his opinions affected only their weight. |
| Exclusion reversed | Molitor v. BNSF Railway Co.2022 IL App (1st) 211486 | Ill. App. Ct. | 2022 | The court reversed summary judgment and the order barring a railroad worker's industrial hygienist, who assessed historical diesel exhaust and herbicide exposure from the worker's account and company documents, holding his methodology was not new or novel and that the trial court had improperly looked behind his conclusions to weigh their foundation. |
Each case links to the free opinion text on CourtListener.
Under amended Rule 702
Since December 1, 2023, Rule 702 says expressly that the party offering an expert must show the court it is more likely than not that the testimony meets each requirement: that it rests on sufficient facts or data, uses reliable methods, and reflects a reliable application of those methods to the case. Questions about the basis of an opinion are no longer automatically matters of weight for the jury. For how the circuits have applied the amendment, see the Rule 702 tracker, which follows each court of appeals; for what that means for preparing or attacking this class of expert, see the guide on amended Rule 702.
Related classes
- Toxicologist (dose-response)
- Cumulative exposure causation expert (asbestos)
- General-causation epidemiologist
Guides
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Last reviewed October 4, 2026. How this page is built: rulings are found by searching court opinions on CourtListener, and each one is read in the opinion before it is summarised here; outcomes are labelled by what the court did with the expert's testimony. No individual expert is named. This page summarises public decisions for orientation and is not legal advice; read the opinion before relying on any ruling.