Maintaining awareness of oxygen levels is paramount to safety. Oxygen (O2) depletion is the most acutely fatal gas threat personnel face and can be caused by a number of factors, including displacement by a heavier gas such as carbon monoxide, or by combustion, including otherwise harmless processes, such as rust. Oxygen enrichment also poses a potential threat because it increases the possibility of combustion and oxidation. RAE Systems’ patented solid polymer and electrolyte O2 sensors are a step forward for the industry because they are safer, don’t use lead, and have an extended life. As a result, these sensors enable a lower total cost of ownership.