These devices are considered "non-lethal" personal self-defense weapons. You must know that possession of defense spray items may be restricted or illegal in some states and cannot be carried onto airplanes (allowed in checked in luggage) and into certain buildings.

Types of Defense Sprays

Self-defense sprays are generally either pepper spray or tear gas. Older defensive sprays, commonly called tear gas, contained chemical compounds such as CS (Orthochlorobenzalmalononitrile) and CN (Chloroacetophenone). Today, the most popular, safest, and most effective defensive spray is formulated with OC (Oleoresin Capsicum), commonly known as Pepper Spray.

CN, or chloroacetophenone was used by the military and police departments in the 60s and 70s as a riot control tear gas, but is not used much anymore. This product is not really a gas, but rather crystals suspend in liquid and placed under pressure to create a vapor.

Tear gas products have proven to be less effective against violent attackers, especially those under the influence of narcotics and alcohol. Additionally, these tear gas products have a fairly slow reaction time of three to thirty seconds.

CS is short for orthochlorobenzalmalononitrile. It is a micro-pulverized irritant. It irritates the mucous membrane of the nose, throat, eyes, and the skin in high concentrations. It works better than CN, but is not readily available to the public.

Both of these chemicals sprays can be toxic and cause serious vomiting, and choking. CN and CS are not all that effective against dogs because they lack lactimal glands.

OC is short for oleoresin capsicum, which is a natural derivative of hot peppers, the active ingredient in Pepper Spray. The essence is extracted, combined with a carrier and propellant, and put into a spray canister.

When it is sprayed into the eyes and face on an attacker, it is extremely painful, but it does not just rely on pain for its effectiveness. OC causes physical effects even in people who are "feeling no pain."

It makes the eyelids slam shut or spasm, causing temporary blindness. When even a small amount is inhaled, it constricts the bronchial tubes, causing extreme choking and coughing, though it does not cut off breathing. It is usually effective on most people and animals, including the mentally ill and those under the influence of drugs and alcohol.

Pepper Spray Strengths

Pepper spray comes in various concentrations, and various degrees of heat (measured in Scoville Heat Units, or SHUs). The heat rating of pepper spray is more important than the pepper concentration percentage.

If you're going to get OC, you should purchase a product which has an SHU rating of 1 to 2 million or more. A 2% to 10% concentration is the best range. Sometimes concentrations higher than 10% do not atomize well, and are therefore less effective.

The primary result of higher concentration sprays lengthen the recovery time beyond the usual 45 minutes or so, and there is no advantage to that in personal defensive situations.

Is OC spray legal?

That depends on your locality. Depending on location, pepper spray laws differ from anyone can buy it, to, as in Massachusetts, one would need a license to purchase and possess it.

Some countries pepper spray is illegal no matter what. It is illegal under FAA regulations to have in carry-on luggage on any airplane, but it is OK to have it in checked baggage.

Using pepper spray irresponsibly can incur criminal or civil liability. Spraying an innocent victim in the face can be a crime. Much like a punch in the face, it would be charged as assault or battery in most jurisdictions.

The justification for using chemical sprays must either be self-defense from personal harm or an arrest situation by law enforcement, and the force must be reasonable under the circumstances. Defense sprays are for personal self-defense only to fight off an attacker. It is not to be used offensively to protect property or on someone you merely dislike.

When used by surprise, pepper spray is an excellent diversion, allowing you time to get away.

Pepper spray has been used by police and federal law enforcement organizations for decades, and it has an excellent safety and effectiveness record. Many instructors of self defense classes recommend it and carry it themselves.

It is probably the best "general purpose" self-defense tool that you can own, though nothing is 100% effective. The spray may not work on some violent, goal-oriented, people, and may not work fast enough to be effective against someone who is armed.