Process safety management

To the editor, The Process Safety Management (PSM) standard promulgated in 1992 by the U.S. Occupational Safety and Health Administration (OSHA) is often described as a performancebased and risk-based standard, and sometimes as a management system [1]. In actuality, it is none of these. The PSM standard defines generally what is required of companies and can only be described as performance-based in that it allows companies to decide how they will meet the general requirements specified. A true performance-based standard would require the definition of measurable outcomes, i.e., performance targets, and the determination of compliance with them using performance measures. Also, thresholds for acceptable performance must be specified. Given that the PSM standard is intended to prevent catastrophic accidents that could impact facility employees, such performance measures should reflect this goal. Ultimately, the overall performance of a facility in meeting this goal is what matters. Of course, performance measures also can be defined for each element of a process safety program that contributes to meeting this goal. Suitable performance measures should be used to monitor compliance with established requirements. Facilities can then decide how they will meet the performance requirements. In its current form, the PSM standard is hazards-based and not risk-based. Indeed, the word “risk” is not used in the standard. The purpose of the standard is defined as providing requirements for preventing or minimizing the consequences of catastrophic releases of toxic, reactive, flammable, or explosive chemicals. The likelihood of such releases is not addressed specifically, although a clarification from OSHA indicates that the requirement for a process hazard analysis to address “a qualitative evaluation of a range of the possible safety and health effects of failure of controls on employees in the workplace” can be met by risk-ranking hazard scenarios using consequence severity and likelihood estimates [2]. Of course, what matters to facility personnel is not just the possible consequences of accidents but also their risk. Indeed, it is actually risk that is being managed by a process safety program rather than safety. All modern industry standards are cast within a management systems framework, including the Responsible Care R