Bruce:
I was one of a couple of instructors teaching a women's self-defense class last week.
One of the instructors brought a can of similated pepper spray manufactured for the purpose of training police officers how to aim the spray.
He let each woman attempt to spray a faux-mugger (with a protective mask) in the face as he approached. Not a single woman came close to hitting the guy even in the body much less in the head and nobody even came at all close to the face.
The point is that if you plan to use pepper spray, you better practice aiming it first. Remember that both you and your target will be moving.