Hi Denis -

The only source of storage requirements, whether temperature or humidity, is the product specifications themselves, which ultimately come from the manufacturer. This is where 2-8C comes from for refrigerated products. The manufacturer of each product did a stability study and determined that 2-8C was the appropriate temperature for storage of that product, to preserve and protect its quality.

Any humidity requirements would come from the same source. Most products don’t have humidity specifications, so thus you have this question. There is of course, a common sense humidity specification of <100% RH, just to prevent unwanted condensation as water can damage products.

I hope this helps,

Paul