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I've seen it claimed that bacteria or viruses can't live on surfaces when the humidity is less than 10%. But I can't find any credible source for this. The earliest source I can find is Popular Science magazine:

Humidity also makes a difference; no bacteria or virus can live on dry surfaces with a humidity of less than 10 percent.

Is this true? And if it is, where is the evidence for it?

  • ncbi.nlm.nih.gov/pmc/articles/PMC229427 page 4 shows reduced survival but not no survival. – Tim Oct 17 '15 at 23:17
  • @Tim: That looks like an answer. Would you like to turn it into one? – Oddthinking Oct 18 '15 at 0:28
  • It depends on what you mean by "live". Bacteria and viruses can turn themselves to spores to protect themselves - basically building themselves a fall-out shelter and go to sleep. While in spore form they're not active. But we have revived bacterial spores that have come back from space riding on the outside of our space equipment. – slebetman Oct 18 '15 at 1:02
  • @Oddthinking yes was on mobile then. – Tim Oct 18 '15 at 8:56
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Here is a graph from a scientific review paper by Jawad A et al. (1996) called Influence of relative humidity and suspending menstrua on survival of Acinetobacter spp. on dry surfaces. A PDF of it can be found at this NCBI page.

Here I've taken the first 6 bacteria from the experiment, and made it into a slightly clearer graph.

Quite clearly, every single bacteria here survived for 2 days or more - and R 584 survived for as many as 8 days.

Humidity also makes a difference; no bacteria or virus can live on dry surfaces with a humidity of less than 10 percent

This experiment seems to have conclusively shown that some bacteria can survive those conditions.

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