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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 returned from ISS on flights 8A, UF2, 9A, and 11A were analyzed for trace pollutants. On average, the air during this period of operations was safe for human respiration. However, about 3 hours into the regeneration of 2 Metox canisters in the U.S. airlock on 20 February 2002 the crew reported an intolerable odor that caused them to stop the regeneration, take refuge in the Russian segment, and scrub air in the U.S. segment for 30 hours. Analytical data from grab samples taken during the incident showed that the pollutants released were characteristic of nominal air pollutants, but were present in much higher concentrations.

The need has recently arisen for the monitoring of formaldehyde levels during manned space flights. A volatile organics analyser (VOA) will be currently used to monitor the air directly for other targeted analytes. This consists of a thermal desorption gas chromatography ion mobility spectrometer. Formaldehyde can not be measured directly using this method as it needs to be derivatised first to provide a more stable compound. A method previously developed for the analysis of formaldehyde in air using on trap derivatisation followed by thermal desorption GC-MS was evaluated at each stage to determine whether the two methods were compatible.

Compared with previous U.S. space flight missions, the risk of atmospheric contamination on board Space Station Freedom (SSF) is substantially increased because of the large number of on-board experiments, long-term storage of chemical wastes, and the release of offgas products into the closed environment over the station's 30-year lifetime. Degraded air quality aboard SSF could affect crew health and safety as well as mission success. This paper describes the development of technologies for an on-board Volatile Organic Analyzer (VOA), an essential component of the Environmental Heath System (EHS) air-quality monitoring strategy that warns the crew and ground personnel if volatile compounds exceed safe exposure limits. Achieving the performance requirements established for the VOA within power and weight constraints led to a novel approach in which gas chromatography (GC) was combined with ion-mobility spectrometry (IMS).

The capabilities of the U.S. Space Station Freedom (SSF) will allow a variety of scientific investigations in the biological and materials sciences. The complexity and duration of some planned investigations far surpass those flown to date on Spacelabs and carry an increased risk of accidental release of toxic compounds. This risk is further increased by the presence of large amounts of utility chemicals for SSF systems. Past experiences on Shuttle flights have confirmed the potential for airborne contamination emanating from both payload and Shuttle systems as a result of thermodegradation during flight. This paper describes the SSF Environmental Health System's air-quality monitoring strategy and instrumentation. A two-tier system has been developed, consisting of first-alert instruments that warn the crew of airborne contamination and a volatile organic analyzer that can identify volatile organic contaminants in near-real time.