In 1972, Harrison Schmitt, an Apollo 17 astronaut accidentally sniffed some moon dust that he and his commander carried back into the Challenger living quarters after their moonwalk. Later, Schmitt suffered from what he described as "lunar dust hay fever". His eyes watered, throat throbbed, and sneezed hard, but these symptoms went away the next day and returned to Earth alive. But this event led scientists to replicate the moondust in their lab for further examination and discovered a scoop of moon dust is toxic enough to kill up to 90 percent of the lung and brain cells exposed to it.
The dust in the moon is sharp because there is no wind to erode it so if these are inhaled deeply, it can slice the astronaut's lung cells. Not only that, it can dramatically increase the risks of developing various cancers because moondust is exposed to proton and UV radiation. Also, since these toxic specks of dust are largely the products of micrometeorite impacts which form their shape sharp, it can injure the unprotected skin and scratch the eye's cornea. Plus, floating lunar soil is electrostatically charged, it can easily cling to an astronaut's clothing and follow him or her back to the living quarters. These particles can clog sensitive equipment, jam zippers, ruin clothing and cause detrimental effects inside the astronaut's body if he or she accidentally ingested it.
Hence, NASA is now developing several dust-mitigation methods for the protection of the astronaut's health. One of it is clogging the nose and mouth with dry clothing while they are strolling around the moon with a certainty that the spread of this toxic dust which might damage expensive equipment and affect others will be avoided by not returning to their quarters; instead, they will float freely until they reached the Earth, safe and sound.