OHSAS 18001 was released by the British Standards Institute in 2007 as a standard that describes the requirements for an Occupational health & Safety Management System (OHSMS). These requirements were used in many companies around the world, however, they did not have the world-wide recognition that comes with a standard released by the International Organization for Standardization (ISO) which is voted upon and agreed by over 100 member nations from around the world. After a justification study by ISO the decision was made to release an OHSMS requirements standard from ISO, utilizing the common formatting used for all ISO management system standards that includes 10 clauses and follows the plan-do-check-act cycle very well.
In October 2013 the ISO 45001 standard was proposed, and ISO/PC 283 (the committee that created the standard) was formed, and worked until December 2015. From 2015 to 2017 a first draft failed to gain approval, but a second draft was approved. The finalized standard was published in March 2018. At this point companies have 3 years after the release, until March 2021, to transition over to ISO 45001 if they have an OHSMS in place to the OHSAS 18001:2007 standard.