Halflings are a people without a home. They wander through the kingdoms of taller races, never staying to long in one location, always searching for a place to make their own.
As they travel they notice a horrible rotten smell. As they travel it gets stronger and stronger forcing them to cover their noses and mouth less they choke on the horrible smell. Stream full of dead fish. Spawning trout die in mass quantities after they spawn littering areas with dead fish dying and deteriorating in the sun.