The Hierarchy of Controls

The Hierarchy of Controls, introduced by the National Safety Council and adopted by OSHA, ranks safeguards by effectiveness: hazard elimination, substitution, engineering controls, administrative controls, and personal protective equipment (PPE). This chapter explores its historical context, including Trevor Kletz's advocacy for inherently safer design, and its application to hydrogen sulfide (H 2 S) hazards. Elimination and substitution pose challenges due to H 2 S's natural occurrence in petroleum processing, but engineering controls, administrative controls, and PPE significantly improve safety. The chapter discusses the implementation of engineering controls, such as ventilation systems and treatment systems, and administrative controls, including work permits and training programs. PPE, such as H 2 S detectors and breathing apparatuses, is highlighted as a last resort. The chapter references OSHA and NIOSH, emphasizing the hierarchy's role in systematically reducing hazards. It concludes by examining the effectiveness of various controls, with elimination being the most effective and PPE the least, and discusses the challenges and benefits of implementation.