Why are industries exempt under OSHA's PSM subject to RMP?

The Program 3 prevention program requirements under 40 CFR Part 68 are almost identical to the requirements of OSHA's process safety management (PSM) standard. OSHA exempts certain industries from the PSM standard. Why does EPA not exempt those same industries from the CAA §112(r) risk management program requirements?

EPA and OSHA have separate legal authority to regulate chemical process safety to prevent accidental releases. EPA has no statutory authority to exempt a source that has more than a threshold quantity of a regulated substance in a process from the requirements of the Risk Management Program rule (61 FR 31688; June 20, 1996). In addition, since OSHA's focus is on accidents that affect the workplace, while EPA's primary aim is to ensure that sources implement process safety management in a way that protects not only workers, but also offsite persons and environmental receptors, certain OSHA exemptions would simply not be appropriate for EPA's purposes. For example, OSHA exempted "remote" processes at which no employees are present; however, EPA protects the public and environmental receptors which may be located near these processes.