Besides one experimental study performed in the 70s, all experimental studies of aerosol deposition in the lung in altered gravity have been led to date by the NASA laboratory of which Chantal Darquenne is a member. All studies but one have been performed in humans during parabolic flights both in reduced gravity (microgravity (µG) and lunar gravity) and in hypergravity (~1.6G). These studies showed a significant effect of gravity on the amount and sites of aerosol deposition in the human lung with gravity having the largest effect in the lung periphery for particles in the size range 0.5–3 µm. The relative distribution of deposited particles between gravity levels is also largely affected by particle size. For coarse particles (~5 µm), we showed a significant shift in distribution of deposited particles away from the lung periphery towards large airways when particles were inhaled in μG. In contrast, for fine particles (0.5-1 µm), aerosol bolus inhalations and studies in small animals suggest that particles deposit more peripherally in µG than in 1G, beyond the reach of the mucociliary clearance system.
More recently, we showed in studies approximating conditions of the proposed lunar habitat that reduced gravity rather than reduced gas density is the major factor affecting deposition in the lungs of astronauts exposed to airborne particulates.
Experimental approaches include:
- Aerosol bolus inhalation
- Gamma scintigraphy
- Darquenne, C., M. Paiva, J.B. West, and G.K. Prisk. Effect of microgravity and hypergravity on deposition of 0.5-to 3-mm-diameter aerosol in the human lung. J. Appl. Physiol. 83:2029-2036, 1997 (PMID:9390977).
- Darquenne, C. and G. K. Prisk. Deposition of inhaled particles in the human lung is more peripheral in lunar than in normal gravity. Eur. J. Appl. physiol., 103:687-695, 2008 (DOI 10.1007/s00421-008-0766-y, PMID:18488244).
- Darquenne, C., M.G. Borja, J.M. Oakes, E.C. Breen, I.M. Olfert, M. Scadeng and G.K. Prisk. Increase in relative deposition of fine particles in the rat lung periphery in the absence of gravity. J. Appl. Physiol., 117:880-886, 2014 (DOI: 10.1152/japplphysiol.00298.2014, PMID: 25170069).
- Darquenne C., K.L. Zeman, R.C. Sá, T.K. Cooper, J.M. Fine, W.D. Bennett and G.K. Prisk. Removal of sedimentation decreases relative deposition of coarse particles in the lung periphery. J. Appl. Physiol., 115:546-555, 2013 (PMID:23743403).
- Darquenne, C. Aerosol deposition in the lung in reduced gravity. J. Aerosol Med. Pulm. Drug Delivery, 27:170-177, 2014 (DOI: 10.1089/jamp.2013.1079).
A full list of publications can be found on Chantal Darquenne's UCSD profile page