I refuse to wear an apron. I witnessed a guy get caught up in a threading machine years back because of one. He leaned over, something caught his apron, and it started wrapping up and pulling him in. THe string around the neck went from a bow to a knot. He lived as someone down the aisle from him saw that something was wrong, and he pulled out his knife and got him out. But not before it gave him brain damage from lack of oxygen.
So for anyone that wears one, make sure it is tied tight at the waist, and DO NOT lean over a running machine, ever, apron or not.