'Overly sterile': Scientists say a dirtier ISS might be healthier for astronauts

Produced by Tarun Mishra

Feb 28, 2025, 11:41 AM

Sterile Environment

Astronauts aboard the International Space Station (ISS) often experience immune dysfunction, skin rashes, and other inflammatory conditions. A study published in Cell suggests these issues may be linked to the highly sanitised nature of the spacecraft.

Limited Microbial Diversity

Researchers found that the ISS has significantly lower microbial diversity than human-built environments on Earth. Most microbes present originate from humans, indicating a lack of exposure to naturally occurring environmental microbes.

Extensive Sampling

Astronauts collected 803 surface swabs from different areas of the ISS—100 times more than in previous studies. Scientists analysed these samples to map microbial and chemical distributions within the station.

Impact of Cleaning Products

The study found a strong correlation between the presence of disinfectants and reduced microbial diversity. The extensive use of cleaning products could contribute to an environment lacking beneficial microbes.

Microbial Distribution

Different sections of the ISS host distinct microbial communities based on their function. Dining areas contain food-associated microbes, while sanitation areas have microbes linked to human waste.

Lack of Environmental Microbes

Compared to Earth environments, the ISS lacks free-living microbes commonly found in soil and water. Researchers suggest intentionally introducing these microbes to improve astronaut health while maintaining hygiene.

Future Space Missions

The findings suggest that incorporating diverse microbial communities could support astronaut health in long-duration space missions. Similar approaches may also benefit people in sterile environments on Earth, such as hospitals.