Makel Engineering, Inc. and Sandia National Laboratories propose to demonstrate an advanced multi-modal sensor system suitable for in-situ analysis of exhaled VOCs for pilots, divers and field patients. Our proposed system will combine a micro-gas chromatograph (GC) and miniature ion mobility spectrometer (IMS) for detection of trace amounts of exhaled breath VOCs with miniature solid state sensors for inorganic compounds found in breath such as oxygen, carbon dioxide, moisture, nitrogen, argon and helium. High concentrations of supplemental oxygen are used routinely by pilots and divers prior to and during missions to prevent and treat decompression sickness, avoid detection during covert operations, and to support oxygenation following pulmonary injury. However, due to PO2T, exposure limits are imposed to prevent damage to pulmonary tissues. Current policy focuses on preventing PO2T in an operational environment by adhering to exposure limits that were developed based on empirical evidence of PO2T. In reality, individuals will have variable tolerance, and imposed generalized limits often leads to more stringent operational restrictions that required for a given individual, impacting mission readiness. Our system will enable breath analysis on the field in real-time, providing a tool to monitor physiological condition and enable adjusting operational conditions to preventPO2T.