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The complexity of the atmosphere aboard the International Space Station (ISS) will require a multifaceted monitoring strategy for both nominal and emergency conditions to protect the health and safety of the crew. Samples to be collected for air-quality assessment will include both archival sampling for ground analysis and on-board automatic analyses. Archival samples will be analyzed after return by standard gas chromatography/mass spectrometry; a separate formaldehyde analysis will be conducted as well. On-orbit analyses are planned for specific combustion products and for specific volatile organic compounds of toxicological significance. The air-lock will be monitored after EVAs to ensure that no propellants are introduced into the cabin atmosphere. Additional remote samples can be collected in sample bags from other ISS elements and brought to the Volatile Organic Analyzer (VOA) for analysis.

Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on the standards that define acceptable air quality, measurements of pollutant levels during the flight, and reports from the crew on their in-flight perceptions of air quality. Air samples from ISS flights 2A.2a, 2A.2b, 3A, and 4A were analyzed for trace pollutants. On average the air during each flight was safe for human respiration. However, there were reports from the crew that they experienced a headache when in certain areas, and strong odors were reported from specific locations of the ISS complex. Inspection of air samples in these locations suggested that several of the solvent-type pollutants (e.g. ethyl acetate, xylenes, and n-butanol) were present in concentrations that would cause a strong odor to be perceived by some individuals.

There are many sources of air pollution that can threaten air quality during space missions. The International Space Station (ISS) is an extremely complex platform that depends on a multi-tiered strategy to control the risk of excessive air pollution. During the seven missions surveyed by this report, the ISS atmosphere was in a safe, steady-state condition; however, there were minor loads added as new modules were attached. There was a series of leaks of octafluoropropane, which is not directly toxic to humans, but did cause changes in air purification operations that disrupted the steady state condition. In addition, off-nominal regeneration of metal oxide canisters used during extravehicular activity caused a serious pollution incident.