Scene Context: Les notices a fine white suspension in the air—"space snow" made of dead skin that doesn't fall to the floor but floats through the cabin, making the air thick and stale.
Essence of the Phenomenon: On Earth, any dust or biological microparticles quickly settle to the floor under the influence of gravity. In weightlessness, they remain suspended indefinitely, forming a hazardous aerosol that can enter the crew's airways or eyes.
Scientific Basis: The human body sheds millions of epidermal cells and dozens of hairs daily. In the closed volume of a spacecraft, this poses a serious threat to life support. To solve this, ventilation systems on space stations (such as the ISS) create continuous artificial airflows. They act as a sort of "gravity," driving dust, crumbs, and liquid droplets toward powerful HEPA filters. The downside of this process is the constant, exhausting low-frequency hum of fans and pumps that never stops.
Current Limitations: Even the most advanced filtration systems cannot purify the air of crew bio-waste and chemical outgassing from equipment with 100% efficiency. Any long-duration space station quickly acquires a persistent, specific odor combining notes of plastic, metal, ozone, and the human body. It is impossible to completely eliminate it without replacing the ship's entire atmosphere.