April 20, 1993: Expert: Gas Used in Davidian Assault Could Not Have Caused Fire

An expert says that the tear gas used by the FBI in yesterday’s assault on the Branch Davidian compound near Waco (see April 19, 1993) is not flammable, and in the form it was reportedly used, could not have ignited the flames that consumed the compound and killed 78 Davidians. Jay Young, a chemical consultant in Maryland, says that a mixture of the chemical, known as CS, and air could be ignited only if the ratio of the gas and the air was within a very narrow range, and that flames could not spread beyond the small area where such a ratio might exist. “I cannot conceive of any foreseeable fire hazard posed by use of the gas,” Young says. CS gas is the Defense Department’s designation for the chemical o-chlorobenzylidenemalononitrile. It can be dispensed either in projectiles like hand grenades or shells, or from gas generators of the type used yesterday. The FBI rammed holes through the exterior walls of the wooden compound and then used gas generators to spray a fine mist composed of a crystalline, powdery substance—the “gas” itself—and a reactive agent which turns the crystalline powder into a heavy mist. Tear gas grenades, which the FBI denies using, might pose a danger of fire, since they use pyrotechnic chemicals to heat the powder and turn it into mist. CS is mildly toxic, and can kill those suffering from asthma, pneumonia, or other pulmonary diseases, but it is considered safe for crowd control by law enforcement agencies. American soldiers are exposed to CS in gas chambers as part of their chemical warfare training. CS is more potent than another common tear gas, w-chloroacetophenone, commonly known as CN or “chemical mace.” It is preferred over CN by many police departments because its effects wear off more quickly than those caused by CN. The FBI confirms that the Davidians had access to a large number of gas masks. [New York Times, 4/20/1993] Years later, the FBI will admit to firing two pyrotechnic gas grenades during the assault, though it will claim not to have fired them into the compound itself (see August 25, 1999 and After).