SCBA are one of the most important items of personal protective equipment used by firefighters and rescue personnel, allowing them to enter hazardous environments to perform essential interior operations. They are also used at non-fire incidents involving hazardous materials and confined spaces where there is a threat of toxic fumes or an oxygen-deficient atmosphere. Catastrophic failures of SCBA are characterized by the sudden and unexpected failure of any component that would subsequently expose the user to a hazardous environment, or introduce a major complication hindering the ability to escape from the environment. Failures of this nature are relatively uncommon occurrences. Evidence suggests that “low-order” failures of SCBA are more common. Examples of these failures include freeflowing or improperly connected regulators, improperly tightened or connected hoses, inadequate face-to-facepiece seal resulting in air leakage, or blown O-rings during cylinder changes. These problems are often attributable to operator error or inadequate preventive maintenance, and are a concern because they reduce efficiency or hamper the coordination required for safe and successful operations. One of the most common failures is the failure to use the SCBA system. Many low-order failures can be prevented through proper operator training. The materials used in the construction of SCBA have physical limitations, though they are extremely durable. They are not indestructible and the potential exists to expose SCBA to factors in the environment that may contribute to or produce failure. The actions highly recommended to prevent SCBA failures are preventive maintenance, user training, problem recognition, regular upgrades, use of standards, pursuit of technology, and record-keeping. 2 appendices