ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 share a high-level structure (HLS), identical core text and terms and definitions.

This framework is designed to facilitate the integration of new management topics into an organization's established management systems.
In addition, ISO 45001 is designed to follow ISO 14001 fairly closely, as it is recognized that many organizations combine their OH&S and environmental management functions internally.

This will simplify the integration of the three management systems.