Overview and Background
OHSAS 18001 is a specification for occupational health and safety management systems (OSHMS).
“OHSAS” stands for Occupational Health and Safety Assessment Series. It defines the requirements for a management system that prevents work-related injuries and ill health within an organization.
In the 1990s, many countries and regions issued their own voluntary OH&S management guidelines and standards (e.g., BS 8800, AS/NZS 4801). Because there was no unified, internationally recognized certification framework, several certification bodies collaborated to develop OHSAS 18001.
This created a third-party certifiable OH&S specification that could be operated alongside ISO 9001 (quality) and ISO 14001 (environment), enabling integrated management. OHSAS 18001 was adopted across manufacturing, construction, services, and other sectors, helping strengthen systematic prevention of occupational incidents.
International standardization progressed within ISO thereafter, and ISO 45001 was published in 2018. ISO 45001 is the successor to OHSAS 18001, which was formally withdrawn at the end of March 2021, three years after the ISO standard’s publication.
Most organizations that held OHSAS 18001 certification have since migrated to ISO 45001. The management practices and safety culture established under OHSAS 18001 have been carried forward into ISO 45001, and the specification is still referenced as a foundation of OH&S management.
Main Requirements and Criteria
The requirements of OHSAS 18001 for an OH&S management system (OSHMS) follow the PDCA cycle common to other management system standards: set policy, plan, implement and operate, check, and management review. Key elements include:
OH&S Policy
Top management establishes a written OH&S policy that demonstrates a commitment to protecting worker safety and health, fulfilling compliance obligations, and continually improving performance. The policy is communicated to all workers.
Hazard Identification and Risk Assessment
Identify hazards associated with tasks, processes, and equipment, and assess the risk (likelihood × severity) of each. Examples include fall risks during work at height or health risks from handling hazardous substances. Prioritize significant risks.
Risk Reduction Measures and Objective Setting
Define and implement risk controls for significant risks, applying the hierarchy of controls where feasible (elimination, substitution/reduction, engineering/administrative controls, and PPE as a last resort).
Set OH&S objectives (e.g., “zero lost-time injuries,” “reduce near-misses by X%”) and establish concrete action plans to achieve them.
Managing Compliance Obligations
Identify applicable OH&S legal and regulatory requirements and establish processes to ensure compliance (e.g., deploying qualified personnel, adhering to documented procedures, conducting statutory inspections).
Structure and Responsibilities
Build the OH&S management structure and clarify roles and authorities at each level. Appoint persons responsible for safety, form safety committees where appropriate, designate work supervisors, and promote worker participation. Plan and deliver required training (e.g., safety training, emergency drills).
Operational Control
Manage day-to-day risks through documented safe-work procedures, signage, provision and control of PPE, preventive maintenance, and workplace monitoring.
Assess risks in advance when changes occur (e.g., new equipment, process changes) and implement controls before implementation. Prepare and exercise emergency response plans (for fire, earthquake, chemical spills, etc.).
Incident Investigation and Corrective Action
When an occupational incident or near-miss occurs, investigate root causes thoroughly and implement measures to prevent recurrence. Keep records of incidents and nonconformities and deploy corrective actions to similar operations that may face comparable risks.
Performance Measurement and Audits
Monitor and evaluate performance against objectives and KPIs (e.g., incident rates, near-miss counts) on a regular basis.
Conduct internal audits to verify that the system is operated in conformity with requirements. Correct deficiencies and document results.
Continual Improvement
Top management periodically reviews the OH&S management system, making adjustments and allocating resources as needed. This cyclical approach progressively raises OH&S performance and supports continual improvement toward a “safer workplace.”
In essence, OHSAS 18001 requires building a systematic framework to control workplace hazards and protect workers’ safety and health. The specification integrated these practices into a single management system aligned with other business management processes. ISO 45001 later added concepts such as “worker participation” and “understanding the organization’s context,” while preserving the core structure inherited from OHSAS 18001.
Significance and Benefits of Certification
Certification to OHSAS 18001 (now migration to ISO 45001) signals that an organization puts worker safety and health first. Externally, third-party certification substantiates OH&S efforts and strengthens stakeholder trust.
Where buyer due diligence includes working conditions, certification serves as evidence that OH&S controls are in place, helping expand business opportunities. From an ESG perspective, OH&S is part of the “social” dimension, and certification supports the organization’s corporate social responsibility credentials.
Internally, the benefits are substantial—most notably, reduced OH&S risk. Systematic risk assessment and controls lower the frequency of incidents and near-misses, reducing human harm and loss. This avoids not only direct costs (e.g., compensation, repairs) but also indirect losses (e.g., downtime, reputational damage).
A safe, healthy workplace increases employees’ sense of security and engagement, helping them focus and improve quality. Worker-driven improvements (e.g., near-miss reporting, hazard recognition activities) tend to become more active, improving organizational culture, communication, and teamwork.
Regular internal and external audits institutionalize compliance checks and continual improvement, preventing oversights. Addressing broader topics such as mental health and overwork within the OH&S framework helps mitigate a wider range of labor risks.
Impact on Products, Services, and Consumers
While OH&S may appear to be an internal issue, it directly affects the stability and quality of products and services. Workplaces with frequent incidents face higher risks of production disruption, defects, and delivery delays; robust safety management reduces errors and supports on-time, high-quality output.
In food processing, strong hygiene and health controls reduce contamination risks. In construction, sound OH&S and quality practices contribute to safer, higher-quality assets. In short, safe work leads to safer products and services, creating indirect benefits for consumers.
In transport and other service sectors, preventing overwork and strengthening safety training reduce accidents, damage, and delays, improving user safety and reliability. Modern consumers also consider corporate conduct; third-party certification (now ISO 45001) provides confidence that products and services are delivered in conditions that protect worker safety and health, influencing purchasing preferences and trust.
In summary, strengthening OH&S contributes to stable supply and higher quality, thereby improving consumer satisfaction. The positive cycle—workers can work safely, and consumers can buy and use offerings with confidence—is made more achievable through frameworks like OHSAS 18001 (and currently ISO 45001).
Relevant International Bodies and Authorities
OHSAS 18001 was not an ISO standard; it was developed through collaboration led by certification bodies. Internationally, the International Labour Organization (ILO) is relevant: its 2001 guideline, “ILO-OSH 2001,” informed the development of OHSAS 18001. National authorities also issued their own OH&S guidelines, and OHSAS 18001 served as a private-sector aggregation of such practices.
As a certification scheme, it was operated similarly to ISO standards: independent certification bodies accredited by national or regional accreditation bodies conducted audits and registrations, and the same network now supports migration audits to ISO 45001.
With respect to regulators, OH&S is primarily governed by national law. OHSAS 18001 (and ISO 45001) embeds legal compliance within a system that also structures voluntary initiatives. ISO 45001 has been adopted as a national or regional standard in many jurisdictions, accelerating international uptake.
ISO published ISO 45001 and promoted migration from OHSAS 18001. Although OHSAS 18001 has completed its historical role, its principles live on in ISO 45001 and in organizational safety culture. OH&S also relates to SDG 8 (“Decent Work and Economic Growth”), making it a field for collaboration among the ILO, ISO, authorities, and industry. OHSAS 18001 served as a precursor; today its legacy is integrated into ISO 45001, providing a stronger, globally harmonized driver for OH&S.