When we see them with their hair loose in videos or interviews, it’s often intentional: either for the visual “wow, we’re really in zero gravity!” effect, or because it feels pleasant and relaxing once the work is done. Hair floating around the head has become somewhat of an iconic symbol of microgravity. The real potential risks do exist, but they are well managed: Hair that falls out naturally (normal shedding) can float around → but the ISS ventilation systems constantly recirculate the air and filter particles extremely effectively (dust, hair, crumbs…). That’s exactly what they’re designed for.