Background
WSIAT Decision No. 469/25 (2025 ONWSIAT 469) offers timely guidance on the interpretation of the Chronic Mental Stress (CMS) framework under s. 13 of the Workplace Safety and Insurance Act, 1997 (WSIA). Although the claim arose from COVID-19 pandemic conditions, the Tribunal’s reasoning is not pandemic-specific and carries broader implications for CMS adjudication where workplace health and safety risks materially exceed normal job pressures.
On April 16, 2021, during Ontario’s 3rd wave of the COVID-19 pandemic and during a provincial stay-at-home order, the worker was assigned to operate a crowded bus through designated COVID-19 “hot spot” neighbourhoods during rush hour. Physical distancing was impossible. During the route, a passenger experienced a severe coughing episode and vomited near the front of the bus. The worker stopped the vehicle and advised his supervisor that he could not safely continue.
Following this incident, the worker developed significant psychological symptoms and received an appropriately diagnosed mental stress injury. WSIB denied the CMS claim on the basis that the work circumstances reflected normal job stress and therefore did not meet the CMS Policy’s “substantial work-related stressor” threshold. The worker appealed to the WSIAT.
The Tribunal had to consider whether the worker experienced a “substantial work-related stressor” within the meaning of s. 13 of the WSIA and the WSIB’s CMS policy, and whether that stressor was the predominant cause of the worker’s diagnosed mental injury. Ultimately, the Tribunal panel allowed the worker’s appeal and granted entitlement to CMS benefits. Why?
Analysis
A central aspect of the Tribunal’s reasoning was its rejection of a static interpretation of “normal job stress.” While operating a crowded bus was ordinarily part of the worker’s duties, the Tribunal found that the pandemic fundamentally altered the nature and intensity of the work: driving through “hot spot areas” during a public health emergency, without the ability to physically distance, exposed the worker to an elevated and objectively verifiable risk of serious illness.
The Tribunal emphasized that what constitutes “normal” workplace stress must be assessed in context. External conditions may transform routine duties into stressors that are excessive in intensity or duration when compared to baseline job pressures. Importantly, the worker’s fear was not purely subjective; it was grounded in a real and heightened occupational health and safety risk.
The decision confirms that exposure to a serious workplace hazard, and fear arising from that exposure, may constitute a substantial stressor under the CMS policy. The Tribunal’s focus was not on the source of the risk (i.e., COVID-19), but rather on its severity, foreseeability, and direct connection to the worker’s job duties. In other words, if the health and safety risk is greater than normal, it may be determined to be a compensable stressor.
One could argue that this reasoning has application beyond pandemic cases. The analysis supports CMS entitlement in non-pandemic contexts where workers may be exposed to extraordinary danger — such as violent incidents, credible threats of harm, or sudden breakdowns in safety systems — provided the risk materially exceeds normal workplace expectations. So even if the work incident(s) may not meet the higher threshold for “traumatic” events under the TMS Policy, this decision could be used to argue that the claim should be allowed under the CMS Policy.
The Tribunal accepted the medical evidence and found that the work-related stressors were indeed the predominant cause of the worker’s psychological injury. Although the worker had pre-existing mental health vulnerabilities, these did not outweigh the causal impact of the workplace conditions. The decision therefore reaffirms that pre-existing conditions do not bar entitlement where work stressors are shown to be the primary cause of the injury.
Limits of the s. 13(5) “employer decision or actions” exclusion
The employer astutely argued that the claim was excluded because the stress arose from routine operational decisions, namely work assignments. However, the Tribunal rejected this characterization and held that the WSIA s. 13(5) “exclusion for employer decisions or actions” does not apply where the substance of the stressor is exposure to unsafe or dangerous working conditions.
The Tribunal cautioned against reframing hazardous exposure as a neutral management decision and noted that where an assignment materially elevates risk to worker safety, the exclusion will not shield an employer from CMS entitlement.
Key take-aways
Decision No. 469/25 reinforces a context-sensitive approach to adjudicating CMS claims and clarifies that extraordinary conditions may convert otherwise routine duties into “substantial work-related stressors”. While grounded in pandemic facts, the decision articulates principles of broader and lasting relevance, particularly for cases involving serious occupational health and safety risks.
For employers, the decision underscores the importance of proactive risk mitigation and careful documentation in extraordinary circumstances. For workers and their representatives, it confirms that while a TMS claim may not succeed, a CMS claim may be allowed where objectively dangerous conditions fundamentally alter the nature of the work — regardless of whether the source of risk is a pandemic or another serious workplace hazard.
Please note: The views expressed in this article are solely those of the author, and do not necessarily express those of the Office of the Employer Adviser.
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