The Incident
On January 18, 2026, Toronto Fire Services responded to a chemical incident at 78 Harrison Garden Boulevard in North York. A worker performing maintenance in the building's pool area had mixed two chemicals together, creating a toxic gas that quickly spread through the enclosed space.
Eight people were taken to hospital with symptoms including respiratory distress, chest tightness, and nausea. The building was partially evacuated while hazmat crews worked to ventilate the area and neutralize the chemical hazard.
What Went Wrong
The worker combined two pool treatment chemicals that should never be mixed. When certain pool chemicals — such as chlorine-based products and acid-based products — come into contact, they produce chlorine gas, a highly toxic substance that was used as a chemical weapon in World War I.
This type of incident is disturbingly common in Canada. Similar chemical mixing accidents have occurred at pools in St. Catharines (2012, 12 hospitalized), Ottawa (2011), and Kitchener (2018, 5 hospitalized).
How WHMIS Training Could Have Helped
Chemical mixing incidents are among the most preventable workplace accidents:
SDS Section 10 — Stability and Reactivity: Every Safety Data Sheet includes a section on incompatible materials. A worker trained in reading SDS documents would check this section before combining any chemicals.
Pictogram Recognition: The exclamation mark pictogram (irritant) and skull and crossbones pictogram (acute toxicity) on pool chemical labels immediately signal danger. WHMIS training teaches workers to read and respond to these warnings.
Supplier Labels: WHMIS-compliant labels include precautionary statements such as "Do not mix with other chemicals" and "Use only in well-ventilated areas." Training ensures workers actually read and follow these instructions.
Engineering Controls: WHMIS training covers the hierarchy of controls, including the need for proper ventilation when working with chemicals in enclosed spaces like pool rooms.
Mixing incompatible chemicals is one of the most common — and most preventable — causes of workplace chemical injuries. Every one of these incidents could be avoided with proper WHMIS training.
Source: CityNews Toronto, January 18, 2026