I've also read and studied about the relative humidity of the air and problems with the lungs if the RH is too low, but giving the right level of detail might become an issue on this one. If relative humidity of the air is too low, it can destroy the alveoli (pockets in lungs where oxygen diffuses into the bloodstream).

Low relative humidity in the air can also dehydrate snakes. The relative humidity in the lungs is always 100%, and when an organism exhales, it breathes out very humid air. The humidity isn't replaced when dry air is inhaled. That requires additional drinking, but when snakes are brumating, they drink less often. Therefore, fairly humid air (up to about 60% or less) is beneficial, but continually moist substrate is harmful. Hope this helps,
Rick