University of California, San Diego (UCSD) researcher Dr. Kim Prisk, Ph.D., is involved in studying the possible effects that lunar dust has on astronauts visiting the Earth’s moon. Astronauts’ good health may depend on the amount of exposure to the lunar particles. To prepare for another journey back to our moon (slated before 2020), researchers within the National Space Biomedical Research Institute (NSBRI), including Prisk, are evaluating how moon dust is deposited in the lungs in reduced gravity. From this they hope to better understand possible long-term negative effects on the health of the astronauts. Findings could influence the design of lunar bases. Secondly, findings could contribute to better healthcare here on Earth. An example is in improved delivery of aerosol medications to the lungs. Prisk, who has been working on spaceflight research at UCSD in some form since 1983 and is also involved with the NSBRI, said there are major questions that need to be answered as we approach sending other humans to the moon. How do we know that our own moon’s dust has such an adverse effect on humans? “We infer that,” Prisk said. “None of the exposures, at most three days, from the Apollo missions showed adverse effects, but compared to long stays the exposures were minimal. However, terrestrial exposures to similar dust have been shown to be very hazardous.” Basically, researchers are asking these questions: How much dust particles go into the lung? Where do they go and how long do they stay? Just how nasty is this stuff? Prisk is an adjunct professor in the Department of Medicine at UCSD. During the Apollo missions to the moon in the late 1960s and ’70s, moon dust particles often clung to astronauts and equipment and were easily transported into the lunar lander following moonwalks. Astronauts even reported that build-up sometimes was so great they could smell the moon dust. There were no known illnesses due to moon dust exposure during that period, but Apollo flights lasted only a few days. Miraculously, the human body has clearance mechanisms to deal with this type of dust influx into the body. “Particles that deposit in the airways are moved by the muco-ciliary system so they are eventually swallowed and eliminated,” Prisk said. “Particles that deposit more peripherally in the alveoli are engulfed by alveolar macrophages and eventually removed, although they stay around a lot longer.” As for long-term effects, Prisk says that previous studies on Earth show that living in a dusty environment has negative health consequences in the long-term. “Things like asthma, chronic lung diseases, et cetera, and short-term effects show evidence for increased risk of cardiac events and ultimately increased hospital admissions for respiratory complaints,” he said. Lunar dust is a health concern because it has properties similar to that of fresh-fractured quartz and it is highly toxic. In the future, Prisk says that stays of up to six months are planned. Long-term lunar bases are in the works. During an upcoming proposed return, astronauts will be exposed to lunar dust for longer periods of time, including missions that could last months. Human lungs don’t respond as well to removing foreign matter like moon dust in low-gravity environments like the moon’s. “In the moon’s fractional gravity, particles remain suspended in the airways rather than settling out, increasing the chances of distribution deep in the lung, with the possible consequence that the particles will remain there for a long period of time,” Prisk said. Our lungs are highly sensitive organs mostly because of their large surface area. The lungs deliver oxygen molecules through a thin membrane directly to the blood. Health risks to astronauts increase as dust particles go deeper into the lungs. NASA (the National Aeronautical Space Administration) has a microgravity research aircraft that it uses to conduct research in this area. The airplane is capable of providing short flights of reduced gravity and zero gravity during steep climbs and descents. During portions of reduced gravity flights, particles are injected into a mouthpiece that the study participants breathe in. Researchers measure how the particles react and behave and how many actually end up inside the lung. Prisk said the research flights have been beneficial so far. “With the reduced-gravity flights, we’re improving the process of assessing environmental exposure to inhaled particles,” he said. Small to tiny particles are the most significant in terms of damage to the lung, with changes or fluctuations in gravity greatly influencing this effect. The next step, Prisk says, is to investigate the risks in more detail, then determine ways to limit exposure to the particles. The design of space suites for astronauts is a work in progress. “Probably more appropriate to ask is how will they change,” Prisk said. “There is extensive work ongoing on new suits. They will likely be much more like hard suits used in diving.”?From these conclusions and the push forward, researchers hope to be able to learn new ways to minimize risk to humans and to lunar equipment. As for benefits here on Earth, the research could give scientists a better understanding of how the lungs work. “If we learn how to target drugs to specific areas inside the lung, it will be possible to achieve optimal results with small quantities of drugs delivered to exactly the right place in the lung, and it will minimize side effects,” Prisk said. The bottom line at this point in the research is determining how to properly protect astronauts’ health when visiting the moon. “The amount of particles entering the lungs depends on how much effort is put into filtration and dust?mitigation, which is the whole point of the studies: to decide what is required,” Prisk added. “But, particle concentration is in the 10s of thousands per centimeter cubed of air are not unreasonable to expect in some circumstances. Considering even a relatively shallow breath might be 500 cm3 and you breathe, say, 15?times per minute, the numbers are large. In the millions.”? How can exposure to such potentially toxic dust be minimized in the long run? “It all comes down to how much effort needs to be put into dust removal,” Prisk said. “If hours have to be spent in decontamination, then that is a significant impact in a mission model that has lunar surface activities happening five days a week.” On the other hand, Prisk said, if a quick clean-down is possible and adequate, then that really helps and moves things along. “It depends on how toxic the dust is. This is under study currently by several NASA teams,” he said. “How long particles deposited in the lung in low-gravity stay there determines how much exposure astronauts can be exposed to. This is a new study of ours.” In the long run, lunar dust and its effects is just one consideration for future moon travel. Astronauts inevitably will be exposed to some lunar dust. The question is just how much. “It is just one of the factors to be considered and worked on. Putting someone on the moon for three days was very, very hard [Apollo],” Prisk said. “Putting a team there for six months makes that a great deal more difficult. But then, exploration is supposed to be difficult, right?” The research organization NSBRI is funded by NASA and acts as a consortium of institutions studying the health risks related to long-duration spaceflight. The institute’s science, technology and education projects take place at more than 70 institutions across the United States. The UCSD School of Medicine is a prominent primary care, teaching and research facility with a specialized program in AIDS research.