Over the past week, we’ve seen tear gas and CS smoke canisters used on people of Ferguson, Missouri. On social media – and in the general media – there seems to be confusion as to the difference between tear gas and CS smoke canisters. Is there a difference?
The Center for Disease Control’s (CDC) ‘Facts About Riot Control Agents Interim document’ explains what tear gas is:
- Riot control agents (sometimes referred to as “tear gas”) are chemical compounds that temporarily make people unable to function by causing irritation to the eyes, mouth, throat, lungs, and skin.
- Several different compounds are considered to be riot control agents. The most common compounds are known as chloroacetophenone (CN) and chlorobenzylidenemalononitrile (CS). Other examples include chloropicrin (PS), which is also used as a fumigant (that is, a substance that uses fumes to disinfect an area); bromobenzylcyanide (CA); dibenzoxazepine (CR); and combinations of various agents.
— Bill Powell (@WPowell19) August 17, 2014
In the CDC fact sheet referenced above, CS is the chemical chlorobenzylidenemalononitrile. This chemical, whose structure is shown at the top, targets the eyes, skin, and respiratory system. From the CDC – National Institute of Occupational Safety and Health (NIOSH) ‘Pocket Guide to Chemical Hazards’ , the symptoms of CS are:
Pain, burn eyes, lacrimation (discharge of tears), conjunctivitis; erythema (skin redness) eyelids, blepharospasm; irritation throat, cough, chest tightness; headache; erythema (skin redness), vesiculation skin
Tear gas is a board classification and a CS smoke canister would fall into this group. To state it explicitly, CS is a type of tear gas. Firing a CS smoke canister at or near individuals in Ferguson means tear gas is being used.
featured image is the structure of CS from chemspider
This post was inspired by @DNLee’s tweet.