Incident Investigation Procedure Guide

What Constitutes a Reportable Incident?

Under the OHSA, employers must report to the Ministry of Labour (MOL) within four hours of becoming aware of any critical injury, fatality, or explosion that occurred in the workplace. Near misses and occupational illnesses must also be investigated, even if they do not trigger the immediate MOL reporting requirement. All incidents—including property damage and near misses—should be investigated to prevent recurrence.

Immediate Response (First 24 Hours)

• Secure the scene and prevent disturbance until investigation is complete
• Provide first aid and emergency services to anyone injured
• Notify the supervisor, employer, and JHSC co-chairs immediately
• Contact the MOL within four hours if the incident is critical or fatal
• Photograph the scene, equipment, and any contributing conditions
• Identify and preserve any evidence (equipment, materials, records)

The 6-Step Investigation Process

• Step 1 — Form the Investigation Team: Include the supervisor, a JHSC member, and a worker representative
• Step 2 — Gather Facts: Interview witnesses separately; collect physical evidence; review training records, procedures, and maintenance logs
• Step 3 — Identify Root Causes: Move beyond immediate causes to underlying system failures (inadequate training, missing procedures, defective equipment)
• Step 4 — Determine Corrective Actions: Develop specific, measurable actions that address identified root causes; apply the hierarchy of controls
• Step 5 — Document Findings: Complete the investigation report with facts, analysis, and recommendations; submit to the JHSC and employer
• Step 6 — Implement and Monitor: Assign owners and due dates for each corrective action; verify implementation; confirm effectiveness at 30 and 90 days

Completing the Investigation

Investigations must be completed within a reasonable timeframe—generally within 30 days of the incident. The JHSC co-chairs must review the investigation report and are entitled to submit their own written recommendations to the employer. The employer must respond in writing within 21 days.

Key Principle: Focus on Systems, Not Blame

Effective incident investigation focuses on identifying and fixing systemic failures—not on assigning personal blame. Workers who fear punishment are less likely to report incidents and near misses. A safety culture that treats every incident as a learning opportunity produces better long-term outcomes than one that focuses on discipline.