OSHA recently issued its explanation of “on site in one location” in the “Application” section of the Process Safety Management of Highly Hazardous Chemicals standard. This interpretation simply means that the standard applies when a threshold quantity of a highly hazardous chemical (HHC) exists within an area under the control of an employer or group of affiliated employers. It also applies to any group of vessels that are interconnected, or in separate vessels that are close enough in proximity that the HHC could be involved in a potential catastrophic release. Details are available in the June 7 Federal Register.