Job Safety Analysis (JSA)

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Overview

A JSA lists task steps, asks 'what could go wrong?' at each, and decides how to prevent it.

It feeds the Permit to Work and the daily toolbox talk.

Step-by-step procedure

Select the task and involve the people who will do it.
Break the task into clear sequential steps.
Identify the hazards at each step.
Rate the risk = likelihood × severity (risk matrix).
Assign controls until residual risk is acceptable.
Assign an owner to each control and confirm it.
Brief the crew at the toolbox talk; everyone signs.
Re-assess whenever conditions change.

The hierarchy of controls (most to least effective)

Elimination — remove the hazard entirely.
Substitution — replace with something safer.
Engineering controls — guards, ventilation, isolation.
Administrative controls — procedures, training, signage.
PPE — the last line of defence.

Roles & responsibilities

Role	Responsibility
Supervisor	Leads the JSA and briefs the crew.
Workers	Contribute hazards and confirm understanding.
Safety Officer	Reviews quality and challenges weak controls.

Common mistakes to avoid

Copy-pasting a generic JSA that doesn't fit the task.
Jumping to PPE instead of higher controls.
Not updating the JSA when conditions change.

Legal requirements (Thailand)

Occupational Safety, Health and Environment Act B.E. 2554 (2011) — the governing workplace-safety law in Thailand.
Employers have a duty to assess and control work risks before work begins.
Ministerial Regulation on the standard for a safety management system B.E. 2565 (2022).

Frequently asked questions

What is Job Safety Analysis (JSA)?

A Job Safety Analysis (JSA) — also called a Job Hazard Analysis — is a simple but powerful tool. The team writes down the steps of the task in order, asks 'what could go wrong?' at each step, and decides how to prevent it. Doing this before work turns vague worry into a clear, agreed plan.

Who is responsible?

Supervisor: Leads the JSA, ensures controls are in place and briefs the crew.; Workers: Contribute real-world hazards and confirm they understand the controls.; Safety Officer: Reviews the JSA quality and challenges weak controls.

What are the most common mistakes to avoid?

Copy-pasting a generic JSA without reflecting the actual site and task. Jumping straight to PPE instead of working down the hierarchy of controls. Not updating the JSA when the scope or conditions change mid-job.

References — Company risk-assessment procedure; ISO 45001; Thai OSH Act B.E. 2554.