The last man to walk on the Moon, astronaut Harrison Schmitt, suffered from an allergic reaction to Moon dust. Speaking at the Starmus Festival in Zurich Switzerland, he described his experience as part of the Apollo 17 mission in 1972.

The dust stuck to Schmitt’s suits, boots and tools, and was transported back to the lunar module, reports Newsweek. When he took his helmet off, he became congested. Describing his experience of inhaling the dust, he said, “First time I smelled the dust I had an allergic reaction, the inside of my nose became swollen, you could hear it in my voice. But that gradually went away for me, and by the fourth time I inhaled lunar dust I didn’t notice that.”

When the crew splashed down, a flight surgeon taking the suits out of the Apollo 17 command value “had such a reaction that he had to stop what he was doing.”

Schmitt sees controlling the finely pulverized mineral as mainly an engineering problem. However, speaking in a 2005 interview he said, “Dust is the No. 1 environmental problem on the Moon. We need to understand what the [biological] effects are because there’s always the possibility that engineering might fail.”

Writing in GeoHealth, scientists studying Moon dust found that long-term exposure to the minerals can cause cell death and DNA damage to lung cells. Stated the article:

Clearly, avoidance of lunar dust inhalation will be important for future explorers, but with increased human activity on the Moon it is likely that adventitious exposure will occur, particularly for individuals spending long periods of time on that body. A detailed understanding of the health effects of lunar dust exposure is thus important, and further defining the cellular and biological impact of materials from various parts of the lunar surface is warranted.