If you look at the astronauts after a spacewalk, their clothing was covered with it. And the said the air had the odor of gunpowder, so the particles were fine enough to be airborne and got into the lungs. Their spacesuits got it in the mechanical connections and could affect the seals. It’s electrically charged as well due to the solar wind. The built up charge is more concerning near the poles where the next mission is supposed to go. 10’s of thousands of volts.