Kim LoweHuman Systems Standards Integrator
Jan 17, 2025
NASA's Office of the Chief Health and Medical Officer (OCHMO) put together a little working group to evaluate hydrogen sulfide (H2S) Spacecraft Maximum Allowable Concentration (SMAC) worths. The group satisfied essentially 3 times throughout February and March 2023, and panel members sent private viewpoint declarations in April 2023. Toxicology topic specialists were picked to lead to a well balanced panel with regard to knowledge in SMAC decisions and particular H2S factors to consider, from both medical and epidemiological viewpoints. Panel members were Dr. Terry Gordon, Dr. Tee Guidotti, and Dr. Joyce Tsuji; OCHMO staff member who assisted in the conversations were Dr. Doug Ebert, Dave Francisco, Sarah Childress, Kristin Coffey, and Kim Lowe.
The objectives of the working group were to:
- Back or suggest modifications to H2S SMAC levels that had actually been proposed by the JSC Toxicology Laboratory
- Evaluation a draft H2S SMAC manuscript prepared by the JSC Toxicology Laboratory
- Supply any extra insight and factor to consider relating to H2S toxicity that ought to be thought about for spaceflight programs
The NASA Spaceflight Human-System Standard (NASA-STD-3001) develops that lorry systems will restrict climatic contamination listed below recognized limitations [V2 6050] Environment Contamination Limit. The JSC Toxicology Laboratory preserves the JSC 20584 Spacecraft Maximum Allowable Concentrations for Airborne Contaminants file, which consists of a table of SMAC worths for a range of chemicals consisting of carbon monoxide gas, ammonia, heavy metals, and a large range of unstable natural substances. SMACs are recorded for 1-hr, 24-hr, 7-day, 30-day, 180-day, and 1000-day time periods for each chemical, and reveal the optimum concentration to which spaceflight team can be exposed for that period.
The organ system that is impacted in addition to the impact (signs) are likewise recorded for each SMAC. To find out more on SMACs, see this short article Exposure Guidelines (SMACs and SWEGs)– NASA and the OCHMO Spaceflight Toxicology technical quick technical short.
A SMAC worth for hydrogen sulfide has actually not formerly been developed considering that it has actually not been of issue in spacecraft. With Artemis objectives returning to the moon there is a possibility that H2S might be launched within spacecraft throughout lunar sample return, provided that this substance might be a part of lunar polar ice. H2S has an extreme odor of rotten eggs and for that reason has a disruptive mental component. Physiologically it has actually been revealed to be an irritant at low concentrations and in high concentrations can possibly cause neurological impacts and unconsciousness.
Hydrogen sulfide SMAC worths will specify safe limitations for spaceflight teams on future objectives and might drive brand-new requirements for tracking and mitigation of this chemical throughout spaceflight.
Bottom line of the evaluation were:
- The proposed 1-hour, 24-hour, 7-day, 30-day, and 180-day SMAC worths were considered suitable and were backed by each of the panel members.
- The proposed 1000-day SMAC worth is so low that the panel's viewpoint is that this SMAC might not be obtainable due to human-generated sources,
