Lunar dust is less toxic than city pollution.
Humanity’s return to the Moon brings challenges beyond propulsion systems and spacesuit durability. One of the silent villains of lunar missions is the dust that covers the entire surface of the satellite. Extremely fine and abrasive, it has long been considered a potential health risk for astronauts. But just how dangerous is it, really?
A study published in the journal Life Sciences in Space Research offers a clearer — and unexpected — answer. According to the research, lunar dust has a significantly lower toxic impact on the lungs than terrestrial dust, especially when compared to pollution particles found in large cities.
During the Apollo missions, astronauts reported irritation in their eyes, throat, and nose after exposure to lunar dust that infiltrated the cabin. Harrison Schmitt, from Apollo 17, described the problem as a kind of “lunar rhinitis.” Although temporary, the discomfort raised concerns about the risks in prolonged missions.
To investigate, scientists used two types of lunar dust simulants — LMS-1, representing lunar mare regions, and LHS-1, from the highlands — comparing their effects with those of Earth’s air pollution particles, specifically PM2.5, which are common in urban areas.
The analyses showed that although lunar dust causes physical irritation and, at high concentrations, reduces the viability of some lung cells, it does not trigger inflammatory processes as intense as those caused by terrestrial dust. “Earth dust induces greater release of inflammatory cytokines, such as IL-6 and IL-8, which was not observed in the tests with lunar samples,” the authors highlight.
One of the critical factors for toxicity is particle size. On Earth, particles smaller than 2.5 micrometers are especially dangerous because they can penetrate deep into the lungs, reaching the alveoli. The same principle applies to lunar dust.
When processed to this respirable size, the lunar dust samples showed a greater ability to reduce cell viability. However, the effects were still milder than those observed with terrestrial pollution particles. Additionally, the tests did not indicate an increase in oxidative stress in cells exposed to lunar dust — a factor often associated with the development of respiratory diseases.
Despite being less toxic than Earth dust, lunar dust is not harmless. Its irregular shape, with sharp edges and highly abrasive texture, can cause physical damage to cells when inhaled. Moreover, in low-gravity environments like the Moon, dust tends to remain suspended in the air for longer periods, increasing the chances of inhalation.
Another point raised by the researchers is that larger particles, which on Earth would quickly settle to the ground, can remain suspended in the lunar environment for longer periods. This increases astronauts’ exposure, especially inside modules and habitats.
📚 Reference: Smith, M. B., Chou, J., Xenaki, D., Bai, X., Chen, H., & Oliver, B. G. G. (2025). Lunar dust induces minimal pulmonary toxicity compared to Earth dust. Life Sciences in Space Research, 45, 72–80. https://doi.org/10.1016/j.lssr.2025.02.005
