Review the item:
To gain attention, Christie has pierced each of her ears eight times on
breezy days,
people hear the tinkling sounds of Christie's unique wind chimes
as the jewelry blows in the wind.
The comma between days and people is completely correct. On breezy days is an introductory prepositional phrase. People hear the tinkling sounds of Christie's unique wind chimes is a main clause.
You need a comma to separate an introductory phrase from the main clause that follows.