OSHA clarifies PSM enforcement, adopts EPA test

Washington – OSHA has adopted a chemical concentration test similar to that of the Environmental Protection Agency to determine whether a chemical is at or above the threshold quantity listed under the Process Safety Management Standard.

For more than 20 years, OSHA has stated that threshold quantities for chemicals under the PSM standard without listed concentrations apply to “commercial grade” chemicals. This can be ambiguous, OSHA said in a June 8 memorandum.

To clarify the issue, OSHA stated in the memo that its new enforcement policy would adopt EPA’s 1 percent test, which requires employers to calculate if the total weight of a chemical without a specified concentration under PSM’s Appendix A is at 1 percent or greater. If so – and the weight meets the threshold limit and the chemical has a partial pressure of 10 millimeters of mercury or greater – then the process is covered under the PSM standard.

In a separate memo also issued June 8, OSHA clarified how to interpret certain language regarding the enforcement of the PSM standard’s recognized and generally accepted good engineering practices. Language similar to “shall” and “must” means the practice is a mandatory minimum requirement to control a hazard, and “shall not” or “prohibited” means unacceptable practices. Deviations from “shall” or “shall not” could lead to a violation.