One of the cleanest places beyond Earth may be making its residents ill. Astronauts aboard the International Space Station (ISS) have had rashes, allergies and the odd infection, and scientists now believe the station’s environment is too clean. Researchers recently concluded that the ISS is so sterile it may be damaging astronauts’ health and have even suggested it might be time to make the station deliberately “dirtier”.
This might seem surprising. We’re constantly told to avoid germs, not embrace them. But the findings from space highlight a growing concern among scientists: that extreme cleanliness can sometimes do more harm than good.
The ISS lacks many of the environmental microbes, the sort found in soil, water and plants, that humans have evolved alongside for millennia. Instead, the microbial life floating around the station comes mainly from the astronauts themselves, such as bacteria shed from the skin.
