I eat my words. The Guardian reports “strong evidence that at least two other crowd control gases have been used on demonstrators in addition to CS gas.” (CS gas or 2-chlorobenzalmalononitrile is the commonest form of tear gas, developed in the 50s and 60s.)
Suspicion has fallen on two other agents: CN gas, which was the crowd control gas used by the US before CS was brought into use; and CR gas.
Some protesters report having seen canisters marked with the letters “CR” – although the Guardian has not been able to confirm this independently.
Both gases can be more dangerous than CS and can cause unconsciousness and seizures in certain circumstances.
Concern began to emerge over the use of more powerful incapacitating agents after reports of gassed protesters falling unconscious and having attacks of jerking spasms.
Those who have experienced the more powerful gas have described it as smelling different and causing an unusual burning sensation on the skin. Others have complained of rashes.
On Tuesday afternoon al-Jazeera reported that some of the recent deaths in Cairo were believed to have been caused by gas asphyxiation.
Read the entire story. Since nobody knows for certain what the gas might be, nobody knows about possible effects, or about antidotes. People are trying atropine, which can be highly dangerous taken without medical supervision. Even the rumor itself is incapacitating.
@SarahCarr offers a contradictory view: “Neurologist in hosp said unusual reactions cld be caused by 1. Exp to huge amounts 2. Date of production 3. Expired gas.”
Regardless, the military are clearly trying ruthlessly to gas the protests into submission. @LiamStack says: “Downtown Cairo has been gassed for 5 consecutive days. The smell of tear gas is everywhere. Every time you kick up dust, you smell tear gas.” @Beleidy calls it “The Battle of Gas.”