Mars dust hides a thyroid risk: perchlorate in soil could challenge future habitats

Mars soil contains about 0.4–0.6% perchlorate salts, per Phoenix measurements, which can disrupt thyroid iodide uptake; NASA’s 2026 dust limits argue inhalation risk is low if total fine-dust exposure is controlled, but any dust inside a habitat remains a risk via suits, airlocks, or repeated excursions. Engineering controls—airlocks, dust-resistant fabrics, filtration—and research into perchlorate-reducing processes are being explored, though authentic Martian airborne dust hasn’t yet been tested.