The Nova Scotia Workers’ Compensation Appeals Tribunal ruled in late 2025 that a longtime employee at a hardboard siding manufacturing facility sustained a compensable workplace injury due to exposure to hydrogen sulfide, overturning earlier decisions that denied his claim.
According to appeal documents, the worker was employed at the facility from 1985 and began working in the company’s wastewater treatment plant (WWTP) in 2010. In February 2019, he filed a claim reporting symptoms that included burning eyes, facial rashes, headaches, nausea and nasal polyps. He attributed the symptoms to exposure to hydrogen sulfide (H₂S), ammonia, phosphoric acid, mould, rust and polymer materials in the workplace.
The worker testified that the smell of ammonia would “hit you in the face” when he opened the hatch in the floor. However, in 2015 and 2018, the company performed testing for ammonia that found levels “well below the regulatory Threshold Limit Values”, appeal documents state.
The worker also stated that no H₂S meters were in place prior to 2018.
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In January 2020, a board case manager denied compensation, concluding the worker’s symptoms were not caused by workplace exposures. That decision was upheld by a hearing officer in January 2021. After new evidence was submitted, the tribunal referred the matter back to the board in March 2023, but the claim was again denied. The worker appealed, bringing the case back before the tribunal.
Following an oral hearing, the tribunal concluded there was sufficient evidence to find the worker sustained a personal injury by accident arising out of and in the course of his employment, caused by workplace exposure to hydrogen sulfide. The board has been directed to determine what benefits result from the decision.
In its analysis, the tribunal emphasized that under the Workers’ Compensation Act, workers are entitled to the benefit of the doubt where evidence is evenly balanced. The tribunal noted that scientific certainty is not required to establish causation and that decision-makers may rely on reasonable inferences drawn from the evidence.
The worker’s adviser argued that elevated hydrogen sulfide levels documented during workplace testing in 2018 were likely present prior to testing, when respirators were not consistently used. The adviser also pointed to increased equipment failures during the winter of 2017–18 and building modifications that reduced ventilation, coinciding with a reported escalation in the worker’s symptoms.
The employer argued that brief elevated readings during testing were not indicative of harmful exposure and noted that the worker wore a respirator during testing. Employer counsel also submitted that testing conditions may have overstated exposure levels and that the worker’s symptoms could be explained by non-work-related factors, including smoking, anxiety, migraines and prior injuries.
The tribunal rejected a narrow focus on whether the worker suffered from an occupational disease, finding instead that the broader question was whether workplace exposure caused a compensable injury. Citing appellate case law, the tribunal stated that “meritorious compensation should not be trumped by a narrow application of the process,” particularly where claim recognition remains unresolved years after the initial filing.
The decision marks a significant reversal after multiple denials and highlights the tribunal’s approach to assessing cumulative workplace exposure and contextual evidence in determining causation.
