Watch the effect in action (45 seconds)
The experiment portrayed in the video was conducted on two ovine tracheal samples exposed at 100% relative humidity (left panel) and the other at 90% relative humidity (right panel) for 15 minutes.
As the clip starts, tiny beating cilia are flickering in the background. Then, debris in the mucus of the right image becomes stationary. The dark spots moving quickly across the left image showed debris being cleared by effective mucociliary transport. After just an hour at the lower humidity, the mucosa has completely dried out.