Pepper spray is a mixture a carrier and OC(oleoresin capsicum) aka pepper. The OC is in a percentage from say .2% to 10%. I have not seen a spray higher that 18% and those seem to be in bear/dog sprays. The higher percentage is not supposed to affect the effects of the spray, only how long the effects last.
If OC is in the eyes, and you want to hit the eyes, it will cause you to want to close your eyes and never open them again. Keeping your eyes closed after being sprayed is a good thing, a wonderful thing, because opening your eyes HURTS!
OC on the skin simply burns and is uncomfortable to say the least.
One's sinus will drain from the OC.
OC that is inhaled will make it hard to breathe. It does not suffocate but it degrades one's physical performance and it might make you sick on the stomach.
A person hit by OC in the face that covers the eyes and is inhaled, will have reduced performance because of swollen airways, eyes will be closed and painful to open, draining sinuses, coughing, burning skin, possibly a wee bit of upset stomach. The person hit by OC is a hurting, blind, coughing, gagging, sinus draining, and possibly puking mass of humanity.
Or not at all. There are some people who are not affected by the stuff. Or they will keep on attacking for a time before the OC effects really take hold.
Almost certainly, the person spraying will be hit by some of the spray but not as bad as the target.
The carrier in OC is important. Some pepper sprays use water
as the carrier and OC is an oil
don't stay mixed so the spray needs to be shaken before use. Not really a good attribute for a defensive spray. Alcohol is often used as a carrier since it mixes with alcohol. The problem is that alcohol is flammable which is not a problem in an open space but in a confined space it can be an issue....
Years ago the NYPD had a barricaded suspect who would not surrender so they threw in OC grenades. After many OC grenades the suspect still would not surrender. Not sure why since he was covered in OC....
They had to go into the room to get him so they tossed in a flash bang.
The flash bang went flash bang, and since the guy was covered in alcohol based OC, it was not a pretty result.
While fact checking some things, I noticed that there do not seem to be any "tear gas" only defense sprays, they all seem to be pure OC or a mixture. Tear gas is not pleasant but I don't think it is as effective as OC.
Sprays are just that, a spray, which is a problem. A spray that is a mist/fog is easier to hit an attacker but the mist/fog is also likely to get blown away and blown into the defender. You also have to close to the attacker which is not a good thing.
A spray that is a stream has a greater reach but is also affected by wind
. It is also harder to hit a moving face but it does give one range and lessons the odds of being sprayed by ones spray.
OC is considered a less than lethal use of force. It is better than nothing and has its uses but it has its limitations.
Some countries and some US state do not allow the possession of OC by civilians.