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?