Hazard assessment is the process of finding what could hurt people at work, judging how likely and how serious that harm could be, and deciding what controls are needed. It is the foundation of every health and safety program and a legal duty for employers in every Canadian province. Done well, it involves the workers who do the job and is repeated whenever the work changes.
Hazards and risk
A hazard is anything with the potential to cause harm: a chemical, an unguarded machine, a fall from height, a heavy load, noise, extreme temperatures, working alone, violence or harassment. Risk is the combination of how likely the harm is and how severe it would be. A good assessment considers all types of hazards:
- Physical: machinery, electricity, noise, vibration, heat and cold, falls, moving vehicles
- Chemical: gases, vapours, dusts, fumes and liquids
- Biological: bacteria, viruses, mould, sewage and bodily fluids
- Ergonomic: lifting, repetition, awkward postures
- Psychosocial: fatigue, stress, violence, harassment, working alone
Formal and field-level assessments
Most programs use two levels of assessment.
Formal hazard assessment
A documented assessment of each job or task, done before the work begins and reviewed periodically. It is carried out by a competent person with input from experienced workers, and it sets the standard controls, procedures, training and PPE for the job. In Alberta, for example, the OHS Code requires the employer to assess hazards before work begins, to involve workers, to document the assessment and to repeat it at set times, including when conditions change. Other provinces have similar requirements with different wording. Check the rules that apply to you.
Field-level hazard assessment
A short assessment completed by the crew at the work location before starting, and repeated when conditions change. It catches site-specific hazards that the formal assessment could not anticipate: weather, nearby work, changes in the area, damaged equipment or an unplanned task.
How to assess hazards
- List the jobs and tasks. Break each job into its main tasks, including maintenance, cleaning, start-up, shutdown and emergencies.
- Identify the hazards of each task. Walk the site, watch the work, talk to workers, and review incident records, manufacturer information and safety data sheets.
- Assess the risk. Many employers use a simple matrix that rates likelihood and severity to set priorities. The aim is to rank hazards, not to produce a precise number.
- Choose controls. Apply the hierarchy of controls, described below.
- Assess what remains. Consider whether the risk left after controls is acceptable, and add controls if it is not.
- Communicate and record. Share the results with workers, document the assessment and keep it where people can find it.
- Review. Update the assessment when work, equipment, materials or people change, after incidents and at regular intervals.
Steps three and five use the same idea: place each hazard by how likely and how serious the harm would be, then check where it lands once the controls are in place.
Choosing controls
Controls are chosen in order of effectiveness. Higher levels remove or reduce the hazard itself, while lower levels depend more on people doing the right thing every time.
| Level | What it means | Example |
|---|---|---|
| Elimination | Remove the hazard entirely | Do the work at ground level instead of at height |
| Substitution | Replace with something less hazardous | Use a water-based product instead of a solvent |
| Engineering controls | Isolate people from the hazard | Machine guards, guardrails, local exhaust ventilation |
| Administrative controls | Change how people work | Procedures, permits, training, job rotation, signage |
| Personal protective equipment | Protect the individual worker | Respirators, gloves, hearing protection, harnesses |
In practice, most hazards are managed with a combination of controls. The point is to start at the top and work down, and to document why a higher control was not practicable when relying on a lower one. See The hierarchy of controls for more detail.
Involve the people doing the work. Workers often know about hazards and shortcuts that supervisors do not see. Their participation is required in several provinces and almost always makes the assessment more accurate and the controls more workable.
A worked example
A maintenance crew is assigned to replace a pump in a basement mechanical room. A formal assessment for pump replacement already exists. Part of it might read like this:
| Task step | Hazard | Controls |
|---|---|---|
| Isolate the pump | Unexpected start-up; stored pressure and hot water in the lines | Lockout of the motor starter, valves closed and locked, lines drained and pressure confirmed at zero before opening |
| Remove the old pump | Heavy, awkward load in a cramped space | Chain hoist from a rated overhead point, two-person handling, clear path to the door |
| Cut and prepare piping | Sparks and hot surfaces; fire | Hot work permit, combustibles removed, fire extinguisher and fire watch |
| Start-up | Leaks under pressure, rotating shaft | Guards fitted before start-up, staged refill, people clear of joints during pressurization |
On the day, the crew's field-level assessment finds two things the formal assessment could not know: a contractor is painting in the same room, and the floor drain is blocked so drained water is pooling. The painting is rescheduled because of the hot work, and the drain is cleared before draining starts. Neither change is dramatic, but both would have mattered.
What a useful field-level assessment includes
- The task and location, written specifically rather than "general maintenance"
- Hazards found on the day, not only those from the formal assessment
- The control for each hazard and who is responsible for it
- Other work going on nearby
- Signatures of the crew, and a supervisor review
- A reassessment when the task or conditions change partway through
Common weaknesses
- Generic assessments that list hazards without linking them to specific tasks
- Defaulting to PPE without considering higher-level controls
- Field-level assessments filled in by habit, with the same entries every day
- Assessments that are never reviewed after changes or incidents
- Results that are not shared with the workers they are meant to protect
Hazard assessment is one element of a broader program, covered in Building a safety program from scratch.
How ehZee can help
We facilitate formal hazard assessments with your supervisors and workers, design field-level assessment forms that people will use, and review existing assessments for gaps. See our safety program development and review service.
Common questions
How often should hazard assessments be updated?
Whenever the work, equipment, materials, site or people change, after an incident or near miss, and at the regular intervals your province and program require.
Which risk matrix should we use?
A simple one that your supervisors understand and apply consistently is better than a detailed one that nobody agrees on. Three or four levels of likelihood and severity are usually enough to rank hazards. Write short descriptions for each level so two people rating the same hazard tend to reach the same answer, and remember that the matrix sets priorities; it does not decide whether a control is legally required.
Do field-level assessments need to be written?
Many provinces and programs expect them to be documented, especially for changing work sites. Even where not strictly required, a short written record helps the crew think it through and shows the assessment was done.