How pepper spray works:
“The active ingredient in pepper spray is oleoresin capsicum (OC), a natural oil found in many types of hot peppers, including cayenne peppers and other chili peppers. OC contains a compound called capsaicin, which is what's responsible for the spicy sensation when you eat a hot pepper. It's odorless, colorless, and even flavorless, but just one milligram (about 0.00003 ounces) of pure capsaicin is enough to cause blisters to form on your skin.
Because capsaicin is the same component that makes peppers seem hot, its potency is measured in Scoville heat units (SHU) -- a heat scale used to rate the heat level of peppers. The overall heat level is based on the amount of capsaicin present. Typical pepper spray is rated between about 500,000 and 5,000,000 SHU. By comparison, a jalapeño pepper is only around 8,000 SHU, and a habanero is close to 350,000 SHU.” http://bit.ly/8NKiuP
When sprayed in the face, pepper spray causes an immediate irritation of the mucus membranes (eyes, nose and throat). This makes if difficult if not impossible to open one's eyes and there is usually a significant amount of discharge from the mouth and nose (snot and drool). Someone sprayed with pepper spray can still fight back and therein lies the issue most police have with it.
Civilian vs. Law Enforcement use of pepper spray:
In a Law Enforcement role, pepper spray works great for dispersing large groups of people and dispatching wild animals. When it come to the normal daily routine of detaining and arresting low-lives, pepper spray fails miserably. About the only thing it does is keep the suspect from running too far. Then the officer has to put his or her hands on a suspect covered in pepper spray usually getting exposed to its effects themselves. Imagine putting a freshly pepper sprayed criminal in the back seat of your car on a hot day...YUCK!
Pepper spray sounds terrible, why would I want it?
Civilians are not law enforcement; they are not arresting and handcuffing people. In a civilian self defense situation, the best option is to get out of the area ASAP. Pepper spray provides you with just that opportunity. As stated before, a person who is sprayed can still fight back, but they can’t see very well and can’t run very far. These are all excellent conditions to extricate yourself from a bad situation and not have to use deadly force. Pepper spray can also be carried most places that guns can’t. The optimal use of pepper spray is to temporarily disable your attacker and flee; you do not need to try and hold him for the police. In addition, pepper spray is very effective against animals, and spraying a mean dog in the park requires much less paperwork than shooting it. ;-)
Pepper spray will never replace a firearm, but it can be an excellent supplement to your self defense arsenal and give you an option other than deadly force.
Look for Part 2: How to carry and employ pepper spray effectively.