In a couple of past threads (that kind of got ugly) many advocated carrying OC as an option to augment their weapon. Some advocates of OC seemed pretty confident that it would stop a confrontation. Here is a video from youtube of OC training for a police academy. This is the worst effects I could find out of an entire series videos on OC. Note how long the OC takes to have enough effect to take the fight out of her. Also note that she completes her tasks in spite of the OC. In a SD situation, you want to remove the threat as quickly as possible - seconds can make the difference between life and death. Would you trust your safety to something that takes so long to effect an assailant?
http://www.youtube.com/watch?v=l2ahK42rYRs
http://www.youtube.com/watch?v=l2ahK42rYRs