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Setting Spacecraft Maximum Allowable Concentrations for 1 hour or 24 hour Contingency Exposures to Airborne Chemicals
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Abstract
Since the early years of the manned space program, NASA has developed and used exposure limits called Spacecraft Maximum Allowable Concentrations (SMACs) to help protect astronauts from airborne toxicants. Most of these SMACS are based on an exposure duration of 7 days, since this is the duration of a “typical” mission. A set of “contingency SMACs” is also being developed for scenarios involving brief (1-hour or 24- hour) exposures to relatively high levels of airborne toxicants from event-related “contingency” releases of contaminants. The emergency nature of contingency exposures dictates the use of different criteria for setting exposure limits. The NASA JSC Toxicology Group recently began a program to document the rationales used to set new SMACs and plans to review the older, 7-day SMACs. In cooperation with the National Research Council's Committee on Toxicology, a standard procedure has been developed for researching, setting, and documenting SMAC values.
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Citation
Garcia, H., Limero, T., and James, J., "Setting Spacecraft Maximum Allowable Concentrations for 1 hour or 24 hour Contingency Exposures to Airborne Chemicals," SAE Technical Paper 921410, 1992, https://doi.org/10.4271/921410.Also In
References
- Kaplan, H. L. Contaminants. The Physiological Basis for Spacecraft Environmental Limits NASA Reference Publication 1045 November 1979
- Coleman, M. E. James, J. T. Spacecraft Maximum Allowable Concentrations for Airborne Contaminants NASA Document JSC 20584 May 1990
- Coleman, M. E. Temporarily assigned Spacecraft Maximum Allowable Concentration (SMAC) limits of atmospheric contaminants for missions up to ten days NASA Memorandum Kerwin J. P. Space and Life Sciences National Space Transportation Systems Program January 15 1985
- Lam, C.-W. Temporary SMACS of 96 chemicals Northrup-Houston Office Memorandum to Coleman, M. E. April 18 1986
- National Research Council Board on Environmental Studies and Toxicology Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants National Academy Press Washington, D. C 1992