As the underwater diving industry continues to use greater concentrations of oxygen in its scuba systems, contaminant ignition becomes of greater concern. In this study, several scuba component assemblies from the Neutral Buoyancy Lab at NASA Johnson Space Center were tested after 1 year of use. They were pneumatically impacted with 50 percent nitrox gas at 20.7 MPa (3000 psi) to evaluate their ignition resistance then disassembled to assess their cleanliness. A follow-up study was then conducted on the ignition thresholds of hydrocarbon-based oil films in oxygen and nitrox environments to characterize the cleaning requirements for these systems. Stainless steel tubes were contaminated to known levels and tested by pneumatic impact. Ignition was determinedwith a photocell connected to the end of the contaminated tube. The results of the scuba component tests, cleanliness evaluation, and contaminant ignition study are discussed and compared for 50 percent nitrox and 100 percent oxygen environments.