Pepper spray is not tear gas. Tear gas is not pepper spray.

Pepper spray is a defense spray. Tear gas can be used as a defense spray.

Two important differences between pepper spray and tear gas are:

1. Tear gas is an irritant, and therefore its effectiveness relies mainly on pain compliance.

Pepper spray is an inflammatory agent. The response to contact with pepper spray is involuntary which makes pepper spray a very effective weapon against drug or alcohol impaired assailants or animals that may not respond to pain.

As Doug Lamb writes in “Tactical Use of Defense Sprays” - When a person is sprayed with OC pepper spray, two things happen instantly. First, the person’s eyes clamp shut, hard. Not only that, but if that person does manage to force his eyes open, the person still cannot see because the OC dilates the capillaries and causes temporary blindness. Second, an immediate fit of uncontrollable coughing doubles the person over because the OC causes instant inflammation of the breathing tissues, restricting all but life support breathing. An assailant who is sprayed with OC stops what he is doing and stops what he is thinking – period. This is true even for those who are drunk, on drugs, or psychotic.

Are All Pepper Sprays the Same?

No.  Pepper sprays are rated in two ways: Percentage of Oleoresin Capsicum in the agent itself, and the “hotness” of the spray, which is measured in Scoville Heat Units (SHU’s).

The percentage of OC has nothing to do with the SHU rating, and vice versa.

One of the biggest misconceptions about pepper spray is that the higher the OC percentage, the hotter and more effective the spray. In most cases, this could not be further from the truth. The best, fastest incapacitating pepper sprays in the world are from 2% to 10% OC. The lighter the fluid, the faster is penetrates the membranes.

So, the percentage of OC is important, but even more important is the SHU rating, as the percentage has nothing to do with the actual SHU rating or "hotness" of the spray.

A pepper spray with 2,000,000 SHU’s is twice as hot as a pepper spray with 1,000,000 SHU’s.

By the way, 2,000,000 SHU’s is a substantial rating for an effective pepper spray.

The Physical Effects of Pepper Spray

Pepper Spray has four physiological effects that may be experienced:

1. Eyes – tearing, involuntary closing or complete closing due to dilation of the eye capillaries. Eyes will appear red/bloodshot for 30 to 60 minutes. People wearing eyeglasses or contact lenses will be equally affected.

2. Respiratory System – immediate inflammation, including swelling of the throat lining which can restrict the airway size. Respiratory functions return to normal within 10 to 45 minutes. The airway will be open enough to allow for sufficient oxygen flow for survival. Due to the reduced airway flow, the person will probably not receive enough oxygen to continue fighting or other sustained physical exertion. Temporary paralysis of the larynx. Uncontrollable coughing, retching, and gasping for air with a gagging sensation in the throat.

3. Effect on the skin: inflammation of the exposed skin with a burning sensation.

4. Effects on muscle coordination: pepper spray exposure may cause a person to lose balance due to the effect of pepper spray on vision.

How Can I Be Assured My Pepper Spray Will Work When I Need It?

You should get in the habit of testing your defense spray every 90 days. To do this first go outside and determine which direction the wind is blowing. Remember to always stand upwind from the direction you are spraying. Depress the firing mechanism for ½ second. This test should be performed upon purchase and every 90 days after that. Be aware that every time you test your spray you reduce the contents of the canister. If you are using a key chain model and you test regularly you will need to replace the unit every 9 to 12 months if you follow the recommended testing procedure above.

How is Pepper Spray Made?

Pepper spray is derived from hot peppers. The oils are extracted from the hot peppers using a high-pressure process. This process leaves you with the active ingredient in pepper spray known as Oleoresin Capsicum, or “OC.” OC is a reddish-orange, oily liquid, insoluble in water. The pure pepper extract is then diluted with an inert ingredient that reduces the “hotness” of the extract to get it down to a useable level for pepper spray.

The History of Pepper Spray

Oleoresin capsicum spray was developed at the University of Georgia by Professor James H. Jenkins and Dr. Frank Hayes, D.V.M., in 1960. That formula under the brand name Halt Animal Repellent was first sold in 1963. Like tear gas, oleoresin capsicum (OC) is non-lethal and induces temporary incapacitation with no known long-term effects. In 1989 the Firearms Training Unit (FTU) of the FBI Academy in Quantico, Virginia, completed three years of intensive research on OC, following which the FBI authorized the use of OC for its special agents and SWAT teams. In addition, OC has proven effective against domestic and wild animals without endangering the animals or the environment. OC, in proper dispensing systems, has been successfully used to stop grizzly bear attacks in Alaska and pit bull dog attacks in California and Texas. The US Postal Service also issues OC to its letter carriers and animal control facilities also issue animal repellent to its officers to protect them from dog bites.

The History of Scoville Heat Units (SHU’s)

Scoville Heat Units (SHU's) is the measurement of the “hotness” of pepper.

All types of chili peppers, including green peppers, jalapenos, and habaneros, all contain an unusually powerful compound found in no other plant, an alkaloid called capsaicin.

Capsaicin is the horticultural term for the genus that chili peppers are classified. A single drop of tasteless and odorless capsaicin in 100,000 drops of water is very noticeable. In fact, capsaicin can be detected by humans at one part per million.

In 1912, pharmacologist Wilbur Scoville developed a standard for measuring the power of capsaicin: the Scoville Organaleptic Test.

Scoville measured exact weights of chili peppers and dissolved the capsaicin in alcohol. This solution was then diluted with sugar water until it was no longer detectable to the human palate. A panel of five taste testers would taste the solution and three of them had to agree before a value was assigned. If, for example, it took 1,000 parts of water to one part of capsaicin, it was said to have 1,000 Scoville Heat Units.

This method was useful for calculating the temperature of peppers used in many pharmaceutical products such has heat rubs. Today, high-performance liquid chromatography is used to measure the capsaicin content in peppers. It measures capsaicin levels in parts per million which is then converted to Scoville Heat Units (SHU’s). The pepper scale ranges from zero Scoville Heat Units for a bell pepper to 5,000 or so SHU’s for a jalapeno, to a whopping 200,000 to 300,000 SHU’s for a habanero. Pure capsaicin is 15,000,000 SHU’s.