ISO 45001: The Complete Guide to Occupational Health & Safety Management

ISO 45001:2018 is the international standard for an Occupational Health and Safety Management System (OH&S MS) — the framework an organisation uses to prevent work-related injury and ill health while continually improving safety performance. It replaced OHSAS 18001 as the global reference standard and follows the shared Annex SL structure used by ISO 9001, ISO 14001 and other modern management system standards, with clauses 1–3 setting the scene and clauses 4–10 carrying the mandatory requirements an organisation is actually audited against. This guide walks through that structure clause by clause, explains in general terms who typically needs it, and outlines how certification unfolds.

What is ISO 45001:2018?

ISO 45001:2018, formally titled Occupational health and safety management systems — Requirements with guidance for use, specifies the requirements for a management system that prevents work-related injury and ill health to workers and provides safe and healthy workplaces. In plain terms, it is a structured way of identifying hazards, assessing and controlling the risks they pose, and building the leadership, planning and review processes needed to keep reducing those risks over time — rather than treating safety as a series of one-off fixes.

The standard is published by ISO (the International Organization for Standardization) and applies regardless of an organisation's size, sector or type. It does not prescribe specific safety procedures or equipment — it defines the management system an organisation must build so that hazard identification, risk control and worker protection are deliberate, systematic and continually improved, rather than reactive.

ISO 45001 replaced OHSAS 18001 as the internationally recognised standard for occupational health and safety management. Where OHSAS 18001 was a British-originated specification, ISO 45001 is a full ISO standard built on the Annex SL framework, which gives it the same structural DNA as the organisation's other management systems and makes integration considerably easier.

The Annex SL structure: why ISO 45001 looks like ISO 9001 or ISO 14001

ISO 45001 follows the "High Level Structure" set out in Annex SL, a common framework ISO uses across many of its modern management system standards — including ISO 9001:2015 (quality), ISO 14001:2015 (environmental), ISO 27001:2022 (information security), ISO 22301:2019 (business continuity) and ISO 50001:2018 (energy management), among others. The practical benefit is significant: an organisation that already has one of these systems in place will recognise the shape of ISO 45001 immediately, and integrating an OH&S MS alongside an existing quality or environmental management system becomes far more straightforward than building each one from scratch in isolation.

Under this shared structure, the first three clauses are introductory and set no direct requirements of their own:

• Clause 1 — Scope: defines what the standard covers and confirms it is intended to apply to organisations of any size, type or nature.
• Clause 2 — Normative references: lists the other documents the standard relies on.
• Clause 3 — Terms and definitions: establishes the vocabulary used consistently throughout, such as "hazard," "worker" and "OH&S risk."

The substance of the standard — the requirements an organisation is actually audited against — sits in clauses 4 through 10. These seven clauses are the mandatory core of the OH&S MS, and each one is significant enough that we cover it in its own dedicated article. Below is an overview of each; follow the links to the deep-dives for the full requirement-by-requirement breakdown.

Clause 4 — Context of the Organization

Clause 4 requires the organisation to understand itself and its environment before building anything: the internal and external issues that affect its ability to achieve its OH&S MS objectives, the needs and expectations of workers and other interested parties, and — critically — the scope of the OH&S MS itself, meaning which sites, activities and workers it actually covers. Getting the scope right here shapes everything that follows. We cover the full detail in our dedicated article on Clause 4.

Clause 5 — Leadership and Worker Participation

Clause 5 places accountability squarely with top management, but it goes further than the equivalent leadership clause in most other Annex SL standards. Alongside demonstrated leadership commitment, a documented OH&S policy and clearly assigned roles and responsibilities, ISO 45001 dedicates explicit, detailed requirements to the consultation and participation of workers — including non-managerial workers — in hazard identification, risk assessment, incident investigation and the development of OH&S objectives. This emphasis on worker participation is one of the standard's most distinctive features relative to the generic Annex SL leadership requirements found elsewhere, reflecting the reality that the people doing the work are often best placed to identify the risks in it. It is explored in full in our Clause 5 deep-dive.

Clause 6 — Planning

Clause 6 requires the organisation to identify hazards, assess OH&S risks and opportunities, and determine the legal and other requirements that apply to it, then set measurable OH&S objectives and plan how to achieve them. This is where hazard identification and risk assessment methodology sit — the analytical backbone that connects the context defined in Clause 4 to concrete, trackable safety goals. Our Clause 6 article covers hazard identification, risk assessment and objective-setting in detail.

Clause 7 — Support

Clause 7 covers the resources needed to run the OH&S MS effectively: people, competence and safety awareness, communication (both internal and with external parties such as contractors or regulators), and documented information — the procedures, records and other documentation the standard requires to be created, controlled and kept current. Our Clause 7 article goes into competence, communication and document control in detail.

Clause 8 — Operational Planning and Control

Clause 8 is the largest and most operational clause, and it is where day-to-day OH&S management actually happens. It covers planning and controlling the processes needed to meet OH&S requirements, managing change, procurement and contractors, and — critically — emergency preparedness and response. This is where hazard controls are put into practice on the ground, and it is the subject of our dedicated Clause 8 deep-dive.

Clause 9 — Performance Evaluation

Clause 9 requires the organisation to monitor, measure, analyse and evaluate how well the OH&S MS is performing, including through internal audits and periodic management review by top management. It is also where evaluating compliance with legal and other requirements comes into focus. The full requirements are covered in our Clause 9 article.

Clause 10 — Improvement

Clause 10 closes the loop. It requires the organisation to investigate incidents, identify nonconformities, take corrective action, and continually improve the suitability, adequacy and effectiveness of the OH&S MS — including by feeding lessons learned from incidents and near-misses back into the system. We explore this in our Clause 10 deep-dive.