First-hand experience with tear gas in a controlled situation I volunteered to experience:
It fucking hurts, especially at high doses. It makes your eyes swell shut. Your skin burns. It’s like being punched in the diaphragm and your lungs won’t inflate. Your nose clogs up and your throat gets full of phlegm. You may cough uncontrollably.
If you can, wear long sleeves, pants, covered shoes, and even gloves and a mask. A gas mask is obviously ideal but most people don’t have those. A non-gas mask won’t do a ton to prevent you inhaling the gas but it’ll help keep the skin of your face from being as exposed.
Get away from the source as soon as you can. Don’t touch your face or eyes. If possible, wash off. Wash your hands first, then wash your face with soap and water. It takes time for the effects to fade; if you can find somewhere safe to sit and wait, it helps. Your eyes will cry it out on their own (that’s what we had to wait for when I did this training) but flushing with PLAIN WATER for 10 minutes will help accelerate the process.
When you can remove your clothing safely, make sure to keep the contaminated side OUT. Try not to let the outside of your upper layers touch your face. Wash your hands again when you’re done undressing. When you can, take a cold or cool shower. Wash your hair first by bending over so it doesn’t run down your body, since hopefully the rest of your skin isn’t exposed, and you don’t want this stuff getting elsewhere.
I don’t have advice for decontaminating your clothes; they washed our gear for us so I’m not sure if there’s special protocols for getting tear gas out of clothing.
