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ISO 45001—Differences to and Migration from OHSAS 18001

ISO 45001:2018, published in March 2018, is the first international standard for occupational health and safety (OH&S). It exceeds the previous benchmark standard in this area—OHSAS 18001—in essential points and will replace it by 2021. This article summarizes the differences between the two standards and provides you with all the facts you need to know about the migration from OHSAS 18001 to ISO 45001.

A Brief History of Occupational Health & Safety Standards

The OHSAS 18001 standard was the first standard for occupational health and safety matters intended to be used internationally. However, it was not published within the ISO framework but initiated by the Occupational Health and Safety Assessment Series (OHSAS) Project Group and domiciled at BSI Group, the UK’s national standard body.

Before its publication in 1999, the market saw a quickly growing number of both national OH&S standards and private OH&S certification schemes, leaving companies with confusion and uncertainty about which standard or scheme to choose. OHSAS 18001 was accepted as a solution to this problem in many cases. However, it was not aligned with the framework of ISO management system standards, which led to additional effort and inconsistencies when implemented at the same time. The 2007 revision of the standard finally facilitated the parallel implementation of OHSAS 18001 and ISO standards.

However, many differences remained and an internationally recognized, uniform standard for occupational health and safety was still a desideratum. The development of ISO 45001 was intended to solve exactly this problem and replace OHSAS 18001 once published. Figure 1 shows the implementation timetable for ISO 45001 (Source: OHSAS Project Group).

Figure: Implementation Timetable for ISO 45001-2018

Figure 1: Implementation Timetable for ISO 45001:2018

Who Is ISO 45001 Intended For?

„ISO 45001 is designed to be used by organisations of any size, sector, or location“, says Richard Jones, who was involved in the development of both OHSAS 18001 and ISO 45001. „It can be used by all organizations to check that their occupational health and safety arrangements are up to the standard; and those organizations with certifications to other ISO management system standards—like ISO 9001 or 14001—may want to add ISO 45001 to help them create a more integrated risk management approach within their organization.“

In view of the fact that OHSAS 18001 is being replaced by ISO 45001, Jones also points out that most organizations already certified to OHASAS 18001 will want to migrate across to the new standard. OHSAS 18001 is set to be discontinued in March 2021 after a three-year migration period, in which the organization has time to re-align its processes to the extended scope of ISO 45001.

The third target group, according to Jones, are those organizations who might be new to international standards or „who just want to benchmark themselves against this new framework, whether or not they are interested in certification“. Jones thinks that ISO 45001 provides a very positive opportunity for safety professionals to play a key role in their organization, helping the top management to understand occupational health and safety matters.

Differences Between OHSAS 18001 and ISO 45001

ISO 45001 draws a lot on OHSAS 18001, and so they are similar in so much as they both use the Plan-Do-Check-Act model (PDCA, also known as Deming or Shewhart cycle) and a risk-based approach. But ISO 45001 also shows a lot of important differences and improvements. Following the same High Level Structure (HLS) as other ISO management system standards, „ISO 45001 concentrates on the interaction between an organization and its business environment while OHSAS 18001 was focused on managing OH&S hazards and other internal issues.“ (ISO, March 12, 2018)

One of the major changes is that ISO 45001 establishes OH&S as a key topic throughout the organization. The occupational health and safety management system has to be integrated into the overall business process with worker participation being required in all parts of the system. Furthermore, ISO 45001 has a much greater focus on leadership and top management, requiring all top managers to take responsibility for OH&S matters. Even the person responsible for Finances now has to be aware of its role in OH&S. All this helps to ensure that health and safety is not seen as a standalone subject but as an integral aspect of any organization, instead.

Another interesting change is that organizations now need to ensure that the occupational health and safety management system is designed to take account of their context. This includes all internal and external factors, which affect the health and safety within the organization, or the OH&S management system itself. It even includes the health and safety practices of contractors and suppliers.

Furthermore, ISO 45001 does not only consider risks, but also puts great emphasis on continually assessing occupational health and safety opportunities and finding innovative ways on improving the OH&S management system.

ISO 45001:2018 OHSAS 18001:2007
process-based procedure-based
dynamic in all clauses not dynamic in all clauses
considers hazards, risks (incl. organizational risks), and opportunities deals exclusively with hazards and risks (excl. organizational risks)
includes the views of all interested parties does not include the view of all interested parties
uses ISO’s High Level Structure does not follow ISO’s High Level Structure

Table 1: Key Differences Between ISO 45001:2018 and OHSAS 18001:2007

What Are the Benefits of Using ISO 45001?

Probably one of the biggest benefits of ISO 45001 over OHSAS 18001 is its much higher chance to be widely accepted across the world. Charles Corrie from BSI Group points out that many countries still do not have adequate health and safety regulations and have also been reluctant to use the former OHSAS 18001 standard. „We are hoping now that with this new ISO standard we will start seeing them adopt the standard and that we will see health and safety improved around the world“, says Corrie. „That has been our objective, and I believe we will succeed.“

With its wide scope, ISO 45001 is a great opportunity to improve the management of occupational health and safety right across an organization’s operations and into its supply chains. It encourages organizations to design in OH&S at the earliest stage possible which, ultimately, does not only safe lifes, but also supports the organization’s business goals and allows it to operate more cost effective and efficient.

With the required participation of workers throughout the system and the responsibility for OH&S matters being assigned to the entire top management, ISO 45001 is predestined to foster better cooperation and respect between managers and workers.

How to Migrate to ISO 45001?

All organizations that are currently certified to OHSAS 18001 and wish to maintain an upright OH&S certification will need to migrate to ISO 45001 by March 2021. While the approach of the new standard is quite different, the basic tools are the same, which means that you can reuse most of what you already have in your new management system.

A great starting point for kicking off the migration to ISO 45001 is the OHSAS Project Group’s Implementation Guidance for migrating from OHSAS 18001:2007 to ISO 45001:2018 document (click to open), which is made available through the ISO Committee website. This document includes so-called correspondence tables, which illustrate the differences between the standards as well as the new requirements in ISO 45001.

In addition to that, most big certification bodies offer guidance on the migration to ISO 45001 and will be ready to help as needed. However, if you have already implemented another ISO management system standard, such as ISO 9001 or ISO 14001, you should already be familiar with all the basics and easily find your way around.


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