OHSAS 18001, Occupational Health and Safety Assessment Series (officially BS OHSAS 18001), was a British Standard for occupational health and safety management systems. Compliance with it enabled organizations to demonstrate that they had a system in place for occupational health and safety. BSI cancelled BS OHSAS 18001 to adopt ISO 45001 as BS ISO 45001. ISO 45001 was published in March 2018 by the International Organization for Standardization. Organizations that are certified to BS OHSAS 18001 were able to migrate to ISO 45001 by March 2021 to retain a recognized certification.

Organizations worldwide recognize the need to control and improve health and safety performance and do so with occupational health and safety management systems (OHSMS). However, before 1999 there was an increase of national standards and proprietary certification schemes to choose from. This caused confusion and fragmentation in the market and undermined the credibility of individual schemes.

BSI Group decided to adopt OHSAS 18001 (OHSMS) and OHSAS 18002 (guidance specification) as British standards.

BS OHSAS 18001 was updated in July 2007 to better reflect ILO-OSH guidelines and additionally, the “health” component of “health and safety” was given greater emphasis.

Since the publication of the International Standard for Occupational Health and Safety Management Systems ISO 45001:2018, BSI cancelled its BS OHSAS 1800x standards and adopted the ISO standard as BS ISO 45001.

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