Harrison Schmitt called it "lunar hay fever." After Apollo 17, he experienced nasal congestion and respiratory irritation that lasted hours. The lunar regolith is unlike any dust on Earth. No weathering. No water erosion. Every particle is a freshly fractured shard of glass and mineral with razor-sharp edges at the microscopic level. And it is electrostatically charged by solar UV radiation, making it cling to every surface it contacts.

The Apollo data is sobering. After just three days on the surface, lunar dust had abraded spacesuit fabric, jammed zippers, degraded helmet visors, and contaminated every interior surface of the Lunar Module. Gene Cernan reported that suit joints were nearly frozen by dust infiltration. For a settlement operating for years rather than days, the dust problem scales from an annoyance to an existential threat.

The particle size distribution is the core issue. Median grain size is approximately 70 micrometers, but the distribution extends down to sub-micron particles. Those ultrafine particles, below 2.5 micrometers, are the respiratory threat. They penetrate deep into lung tissue. In reduced gravity, they remain suspended in air far longer than on Earth. Cabin air filtration must achieve HEPA-equivalent performance, continuously, for years.

The mitigation architecture I favor starts at the airlock. No lunar dust enters the habitable volume. Period. This requires a multi-stage approach. Outer airlock with electrostatic dust removal. Suit docking ports where the EVA suit remains outside the habitat and the crew member ingresses through the back of the suit directly into a clean environment. The suit exterior never enters the habitat.

Suit port architecture works for crew. It does not solve the problem for cargo, equipment, and samples that must come inside. Every rock sample, every piece of replacement hardware, every tool that goes outside and comes back must pass through a decontamination protocol. I am designing a UV-electrostatic cleaning chamber that can remove 99.7 percent of surface-adhered particles. But 0.3 percent of a serious problem is still a problem.

Long-term, the most effective mitigation may be eliminating surface EVAs entirely for routine operations. Teleoperated robots handle all exterior maintenance, construction, and resource collection. Humans go outside only for tasks that require direct presence. Every EVA becomes a calculated risk rather than a daily activity. The settlement that survives is the one that keeps the dust outside and the humans inside.