Protection against biological degradation

Nothing much happens biologically below 50% RH

This applies to micro-organisms. Bugs with legs and wings can travel to find water.

There must be no source of water available to mobile organisms

In practice, less than 70% RH at 20 ℃ is usually safe. Objects without nutritious components or contaminants will be safe at much higher RH. But there is no practical way of ensuring freedom from nutritious contaminants.

See the RH section for a graph of environmental limits to mould growth.

Pest destruction by extreme temperature may be OK

There are currently methods for pest destruction, sometimes used routinely without evidence of pest infestation: sudden cooling to -30℃ and heating to over 55℃. These seem intuitively to be risky procedures; should they be condoned by this standard? Exceeding the standard limits in a good cause does not prevent damage, but there isn't much evidence for damage.