Gap AEH Watch Item/NSBRI Research: What are the effects of lunar gravity on permissible exposure limits for inhalation of lunar dust? (Closed)
Last Published:  07/31/18 09:30:04 AM (Central)
Responsible Element: Space Human Factors and Habitability (SHFH)
Status: Closed
Closure Rationale
These risk assessment considerations were incorporated in setting the lunar dust PELs. This has been addressed in the limits set in NASA Standard 3001 Vol. 2 Revision A. Supporting studies include:
  • Prisk, G.K., Sa, R.C., Darquenne, C. 2013. Cardiogenic mixing increases aerosol deposition in the human lung in the absence of gravity. Acta Astronautica 92(1):15-20.

Description
The deposition of aerosols from the environment in the lung presents a health risk. For particles larger than 0.5 micron, such deposition is strongly influenced by gravitational sedimentation. In microgravity, deposition by gravitational sedimentation is absent, and as a consequence, airway particle concentrations are higher than in 1G, enhancing aerosol transport to the alveolar region of the lung. The presence of previously unaccounted for complex mixing patterns in the periphery of the lung, combined with high alveolar aerosol concentrations, results in high deposition in this sensitive region of the lung in microgravity.  The deposition of particulate matter (PM) in the human lung is known to bring with it both long-term and short-term adverse health consequences. The deposition of particles in the lung is strongly influenced by gravitational sedimentation.  Normal gravity provides a screening effect whereby inhaled PM larger than 0.5 micron is mainly deposited in the larger airways where it is cleared by mucociliary clearance transport within approximately one day. However in low-gravity, such as that on the surface of the Moon (~1/6G) and Mars (~3/8G), this protective 'gravitational screening' is less efficient, and as a result particles are deposited in the sensitive alveolar regions of the lung where residence times are very much longer. Clearance rates from the lung of particles deposited in low-gravity are likely to be substantially reduced compared to that in 1G, resulting in increased residence times of these particles in the periphery of the lung, enhancing their potential to cause lung damage.
Target for Closure
No Target for Closure available.
Mappings
Risk Risk of Adverse Health & Performance Effects of Celestial Dust Exposure
You are here! Gap AEH Watch Item/NSBRI Research: What are the effects of lunar gravity on permissible exposure limits for inhalation of lunar dust? (Closed)
Completed

Documentation:
No Documentation Available