{"id":331180,"date":"2025-12-17T01:35:20","date_gmt":"2025-12-16T15:35:20","guid":{"rendered":"https:\/\/www.nasa.gov\/?p=208755"},"modified":"2025-12-17T01:35:20","modified_gmt":"2025-12-16T15:35:20","slug":"exposure-guidelines-smacs-and-swegs","status":"publish","type":"post","link":"https:\/\/www.vibewire.com.au\/?p=331180","title":{"rendered":"Exposure Guidelines (SMACs and SWEGs)"},"content":{"rendered":"
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4 min read<\/p>\n

Preparations for Next Moonwalk Simulations Underway (and Underwater)<\/h1>\n<\/div>\n<\/div>\n<\/div>\n
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\"Commander<\/a><\/div>\n<\/figure>
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NASA astronaut Steve Swanson, Expedition 40 commander, holds the Carbon Dioxide Removal Assembly (CDRA) in the Kibo laboratory of the International Space Station. (30 June 2014) <\/div>\n
NASA<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

The JSC toxicologists establish guidelines for safe and acceptable levels of individual chemical contaminants in spacecraft air (SMACs) and drinking water (SWEGs) in collaboration with the National Research Council’s Committee on Toxicology (NRC COT) and through peer-reviewed publication.  The framework for establishing these levels is documented for <\/a>SMACs<\/a> and SWEGs<\/a>, and recent refinements to the Methods<\/a> reflect current risk assessment practices.<\/p>\n

In addition to official SMACs used for the evaluation of spacecraft air, JSC toxicologists set interim 7-day SMAC values that are listed in NASA Marshall Space Flight Center’s Materials and Processes Technical Information System (“MAPTIS”), which is used to evaluate materials and hardware off-gassing data.  <\/p>\n

Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants<\/h2>\n

A table listing the official NASA SMAC values is published in JSC 20584 (PDF, 1MB)<\/a> (Last revised – June 2024). References for the published values are provided below:<\/p>\n