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Dreamliner 787 sweaty passengers may be causing fires | Plane Talking
Note: If you calculate it, you get dew point -3°C (fuselage conditions 80kPa, 26°C, 15%). That means that at FL no liquid water condensation can occur but only icing on cold surfaces. It can melt lately, when a temperature of the part increases. But I am not sure whether 15% is valid for air inlet, average humidity in the cabin or for outgoing air.
BTW I believe that you can hardly feel difference between 5 and 15 percent of humidity.