Monitoring the microbial burden in manned space stations

Astronauts on mission on the International Space Station (ISS) experience the uniqueness of this space station in all its aspects. While living in space and inside sophisticated space vehicles, astronauts face unique stressors that they did not encounter before on Earth and its natural environment. Microbial contamination is a stress factor per se and can be of health relevance in the condition of an impaired immunity. As being confined in space, not surprisingly, such a man-made environment will generate its own unique microbial popuation, which mainly originates from the crew but also includes environmental microorganisms. Most of these microorganisms (both environmental and from human origin) do not present severe hazards for healthy people; however, they can pose threats to astronauts with reduced immune response. Therefore, the total load and diversity of environmental microorganisms needs to be controlled, to guarantee adequate living quality and reduce the risks of harmful effects on the crew. Thus, in an effort to reduce the health hazards posed by microbial contamination, international quality standards for air, surfaces, and water have been defined and prevention, monitoring, and mitigation measures have been implemented by the space agencies.