You have been on site when the radio goes quiet and then someone starts yelling. The next sixty minutes determine whether your company gets through this by the book or spends the next two years in MOL enforcement. This is the reporting landscape from someone who has stood in that circle of hard hats waiting for the inspector.
Ontario Regulation 834 under the Occupational Health and Safety Act defines "critical injury" as an injury of a serious nature that meets any one of seven conditions. The list is short and absolute — there is no room for interpretation. A critical injury is one that: (1) places life in jeopardy, (2) produces unconsciousness, (3) results in substantial loss of blood, (4) involves the fracture of a leg or arm but not a finger or toe, (5) involves the amputation of a leg, arm, hand, or foot, (6) consists of burns to a major portion of the body, or (7) causes the loss of sight in an eye. Notice what is not on the list. A broken finger is not a critical injury. A laceration that bleeds but does not produce "substantial" blood loss is not critical. A concussion where the worker never loses consciousness may not be critical — though if life is in jeopardy it still qualifies under criterion one. When you are standing on site trying to make the call, the safe move is always to report. You cannot get in trouble for over-reporting. You can absolutely get in trouble for under-reporting. If any one of the seven applies, the injury is critical and OHSA section 51 kicks in immediately.
Section 51(1) of the OHSA is direct. When a person is killed or critically injured at a workplace, the constructor (if any) and the employer must notify an inspector immediately by telephone or other direct means. That phone number is 1-877-202-0008 — the Ministry of Labour, Immigration, Training and Skills Development Health and Safety Contact Centre. It operates 24 hours a day, 7 days a week, including statutory holidays. "Immediately" means as soon as the scene is safe and emergency services have been contacted. Not at the end of the shift. Not the next morning. Not after you talk to your lawyer. Immediately. The same section requires you to also notify the joint health and safety committee (JHSC) or health and safety representative, and the trade union if one exists, immediately. These are separate from the MOL call — do not assume one notification covers the others. The practical sequence on site is: call 911 if needed, stabilize the scene, call MOL at the number above, then notify your JHSC member and union steward. A written report must follow within 48 hours to a MOL Director. That report must contain prescribed information including names, time, location, description of what happened, and the nature of the injuries. Assign someone to start writing it within the first hour while details are fresh.
This is the rule that trips people up the most. Under OHSA section 51(2), when a person is killed or critically injured at a workplace, no person shall interfere with, disturb, destroy, alter, or carry away any wreckage, article, or thing at the scene of or connected with the occurrence until an MOL inspector gives permission. The only three exceptions are narrow and specific: (a) saving life or relieving human suffering, (b) maintaining an essential public utility service or a public transportation system, and (c) preventing unnecessary damage to equipment or other property. That means you do not clean up the blood. You do not move the ladder. You do not coil the rope. You do not pick up tools. You do not power-wash the area. You rope it off and you wait. The inspector needs to see the scene exactly as it was. Photographs help, but they do not replace the physical scene. If you moved something to save a life — that is fine, that is exception (a). Document exactly what you moved and why. When the inspector arrives, walk them through it. The biggest enforcement action I have seen on a construction site was not for the fall itself — it was for disturbing the scene before the inspector arrived. The company argued they were "preventing damage." The inspector did not agree. Preserve the scene.
After the immediate phone call to MOL, OHSA section 51(1) requires the employer to send a written report within 48 hours to a Director of the Ministry of Labour. The regulations prescribe the information this report must contain: the name and address of the employer, the nature of the occurrence, the time and place of the occurrence, the name and address of each person involved, a description of the machinery or equipment involved, the nature of the injuries, the name and address of each witness, the name and address of the physician or surgeon who attended the injured person, and the steps taken to prevent a recurrence. This is not a casual email. It is a formal document that may be used in a prosecution or inquest. Get your facts straight, have someone review it, and keep a copy. The 48-hour clock starts from the time of the occurrence, not from when you finished the phone call. If the incident happens Friday afternoon, the written report is due by Sunday afternoon. Weekends do not extend the deadline. For non-critical injuries under section 52, the written notice deadline is 4 days, and it goes to the JHSC/H&S rep, the trade union, and a MOL Director if an inspector requires it.
Separate from the OHSA reporting obligations, the Workplace Safety and Insurance Act requires the employer to file a WSIB Form 7 (Employer's Report of Injury/Disease) within 3 business days of learning of any workplace injury or illness that causes a worker to require health care or to miss time from work. Business days means Monday through Friday excluding statutory holidays — so a Friday afternoon injury gives you until the following Wednesday. You can file Form 7 online through the WSIB employer portal at wsib.ca. The Form 7 is about the claim, not the investigation. It asks for the worker's information, the date and time of injury, the body part affected, how it happened, and the worker's earnings. Failure to file on time can result in penalties from the WSIB — and if a worker files a Form 6 (worker's report) before the employer files the Form 7, that raises questions the WSIB will follow up on. File early. Even if you are still investigating, file what you know and amend later. The WSIB Form 7 and the OHSA written report serve different purposes and go to different agencies. You need both.
The OHSA does not require you to report a near-miss — an event where no one was injured but easily could have been. A scaffold plank that slips but lands where nobody was standing. A load that swings but misses the worker by a foot. A trench wall that shows signs of failure but nobody is in it yet. None of these trigger section 51 or section 52. But the smartest site supervisors track every single one. Near-misses are leading indicators — they tell you where the next real injury is going to come from before it happens. The CSA Z1000-14 standard on occupational health and safety management recommends formal hazard identification and reporting processes that include near-misses. A five-minute debrief at the toolbox talk, a quick entry in the site log, a photo of the condition — that is all it takes. Sites that track near-misses and act on them have lower critical injury rates. Period. The other practical reason to document near-misses: if a real injury does happen later in the same area or from the same hazard, your near-miss records show the MOL inspector that you were aware of the risk and taking steps. That is the difference between a company that gets orders and a company that gets charges. Track the near-misses.