Nope. Instead they hack, retch, and struggle to breathe. Or pour Coke on their face?
Tear gas was a hot news topic back in February or so, when protestors in Egypt where getting hosed down with the stuff. It’s coming back up now, since police around the country are using it to clear out Occupy Wall Street camps and such.
And so with this surge back to the forefront of the news is the popping up again of urban myths surrounding tear gas. The one I’m talking about in particular is that acid (eg vinegar, Coke, etc.) can protect a person from the effects of tear gas. But before we get into if that actually works, we need to first define what tear gas is.
There are a fair few of lachrymators out there. The most common are CS, CN (aka Mace), DM, CR, and CA. Aren’t those names helpful? Most are called after the initials of the inventors. CS, synthesized in 1928 by Corson and Stoughton, is what is usually called tear gas and is most commonly used in the US (according to this book chapter about riot control agents, pdf). The chemical name is o-chlorobenzylidene malononitrile and it looks like so:
The structure of CS. I think I've given up on ChemDraw.
Okay, so what do we have here? We’ve got a benzene ring, a carbon-carbon double bond, two cyano groups, and a choloro group. According to this article (pdf), tear gas works by reacting with the water in our mucous membranes–that is eyes, nose, throat. The choloro group is the culprit here. It combines with water to make hydrochloric acid (HCl), which as you might imagine, is quite the party pooper. [ETA: CRAP! This is actually not right, as was pointed out by an astute commenter. I will update soon with the actual mechanism. Sorry about that.]
So would adding a mild acid to your face keep the stronger acid from forming? Well, Coke has phosphoric acid in it, which is a strong acid. Vinegar is a weak acid. Water is an even weaker acid. Of all those, phosphoric is the most likely to donate an H+ over to the choloro. But, in water (such as your eyes), hydrochloric acid falls apart to make H+ and Cl– anyway. So is pouring acid into your eyes really going to help you? Not sure about that.
Coke is it?
I suppose that it could have the same protective as sunscreen. That is, give the sun something to break down on your skin other than, well, your skin. But I think that dousing your face with a can of Coke is not the best way to go here. It probably won’t do too much, except attract bees. (Amirite, chemists? Weigh in here.) I think a bandana soaked in some acidic substance and draped over the face may work better. Sure you won’t be able to see, but if you’re teargassed you won’t be able to see where the heck you’re going either, because of the tears. Alternatively, according to the paper I cited above, drying out the eyes after you’ve been teargassed is the best way to make it go away fast. Hear that OWSers? Make sure to keep your hair dryers with you at all times.
Also noted in the book chapter about riot control agents is that animals are not so susceptible to the aerosol effects of tear gas, because they are covered in fur. So, best defense against tear gas: turn into a bear. Then the bees probably won’t bother you anyway.
Oh, for those of you getting hyper about those cyano groups up in the CS structure, they aren’t particularly harmful. Quoth the riot control agents chapter:
“If one were to absorb completely all the CS during a 1-minute exposure at 10 mg/m3, and if both cyanides on the molecule were liberated — and evidence suggests that only one is liberated — the
total amount of cyanide received would be equivalent to that received from two puffs of a cigarette.”
I think the big picture here is that you shouldn’t smoke.
No seriously, you really want to avoid tear gas if possible. Yes, you can imagine that it sounds nasty and all, but I’m telling you it really really sucks. I should know, as I’ve been tear gassed three times.
I should say in my defense that in two cases I was an innocent bystander. The third was from malfunction of safety equipment. Um. Sure, that’s what I’ll call it.
The first time was at a Grateful Dead concert. (Hey. Don’t judge me.) Some geniuses decided to jump the back gate at Deer Creek, the police came and set off tear gas canisters, and I happened to be on the wrong side of the wind at the wrong time. Really, I was in the parking lot, I wasn’t even at the show. The most horrible thing about that is there was a woman next to me holding a baby that was maybe 6 months old. Hearing a baby choke on tear gas is something I don’t ever want to repeat. Ever. Being teargassed feels like you are breathing needles. Fortunately, I only got a very light dose that time.
The second time was only marginally my fault. I was working at a bank, as a teller. Do you know that in all cash drawers is a pack of $20s, sometimes real, sometimes fake, that you’re supposed to hand over if you get robbed? It’s called a bait pack. In some cases, all the serial numbers are recorded so the bills can be traced. But in other cases, such as this particular bank, the bait pack consists of a rectangular packet of dye and sensor, sandwiched between two $20 bills, called a dye pack. The dye sensor, I was told, is ONLY SUPPOSED TO GO OFF WHEN IT GOES PAST THE OUTSIDE DOORS. This is important.
An exploded dye pack. Yep, it really looks like this.
I had just started working there, and was talking to the manager about something at my window, training type stuff. She mentioned the dye pack, and me being me said, “Wow, that’s cool. Can I see it?” Sure, she said, so she deactivated the police alarm on the drawer (the bait pack is in a special slot attached to a silent alarm, at least it was at this bank), pulled out the dye pack, and handed it over. I gently lifted up one of the $20s to look underneath, and the thing started making popping noises at me. The manager yelled, “Aaaaah!! Get rid of it, get rid of it!” So I chucked it under my desk and we both bolted for the back room. She slammed the door and we watched, with the other tellers, as a giant magenta plume filled the two story marble lobby. And the funny thing? It wasn’t just dye, there was tear gas in there as well.
Fortunately, it was about five minutes to five so there weren’t any customers in the lobby. Unfortunately, my dad also worked at the bank (vice president of something, which is how I go the job, yay nepotism), and it was kind of a small bank. Word traveled fast. Approximately three minutes after the dye pack went off, the phone rang on the teller line. “So,” my dad said, “I hear you tear gassed the whole lobby.”
The worst part was that we all had to walk through the lobby to get out, which meant also through the tear gas. I put my sweater over my face and ran for where I vaguely remembered the door to be. Amazingly I didn’t crash into anything, but got a HUGE dose of the tear gas. I had to wash my clothes three times to get rid of all traces.
The last time was after Bobby Knight got fired from IU. Again, wrong place wrong time for me. I was downtown with a friend, there was a kerfuffle going on, and for some reason she wanted to see what was going on. We walked a block towards the noise, then I saw the cops and caught a whiff of what was now a familiar smell, so I grabbed her arm and dragged her the hell out of there. Our lips and eyes burned a bit, but that was all really. Narrow escape.
Big big take home message: don’t get teargassed, even if you do get amusing stories out of it. I intend to avoid it from now on.