The use of liquid hypergolic propellants presents a significant challenge for sea-basing under current Navy regulations since they are both toxic and an explosion hazard. Small propellant leaks that result in low airborne concentrations require a response that protects personnel by maintaining concentrations below the levels recommended by the National Institute of Occupational Safety and Health, especially in manned spaces. For larger leaks, it may not be possible to maintain these low concentrations. Under these circumstances, the purpose of the mitigation system is to prevent the build-up of explosive concentrations.