The National Institute of Standards and Technology (NIST), with funding from the U.S. Fire Administration (USFA), has released its final report on a study conducted to determine at what temperatures and conditions self-contained breathing apparatus (SCBA) facepiece lenses melt or degrade. Thermally degraded and melted SCBA facepieces have been identified as a contributing factor in certain fire fighter fatalities and injuries. The SCBA facepiece lens is often considered the weakest component of a fire fighter’s ensemble in high heat conditions, but the level of thermal performance for the facepiece lenses was not well understood. The NIST study demonstrates a range of realistic thermal exposures and environmental conditions, which can result in thermal degradation and even catastrophic failure of facepieces.