Perhaps this discussion should change focus to what IS recommended to deal with unwanted dampness. In order to do that, we would need to know more about what the problem is – why the space is damp, what the negative consequences are for the collections, etc. Relative humidity issues are very specific to the details of the situation; high RH levels are not necessarily bad for every kind of collection, but actual drips or standing water is another matter.
A mechanical humidifier is sometimes useful but a better long-term solution might be to move the collection if it is really at risk or to stop the entry of water at its source. Improving the building envelope is a lot better than measures that have to be monitored constantly.