‘Chemical Bomb’ Thrown at Protestors

A short article on WGME.com has created a minor stir on the Internet including calls for a Homeland Security response. The reason for this is that the article describes an incident at the Occupy Maine encampment in Portland, ME; the incident involved a ‘chemical bomb’ thrown at into the tent area. The problem is that the term ‘chemical bomb’ conjures up images of sarin causing multiple, hideous deaths. The device used in Portland had nothing to do with chemical weapons.

The Devices

What the article actually describes is a fairly common device used to ‘attack’ mail boxes across the country; “a bomb made of kitchen chemicals in a Gatorade bottle”.  There are a number of variations of this ‘explosive’ device depending on the particular combination of chemicals used. They all consist of two or more chemicals sealed in a plastic container. The two chemicals react producing some sort of gas. As the gas production proceeds pressure inside of the bottle increases until the plastic container can no longer contain the pressure. The container ‘catastrophically’ fails producing a large pop and spraying the residual chemicals over a relatively small area.

Chemical Risk

Depending on the chemicals used, there may be a minor residual chemical threat involved. If cleaning chemicals (containing ammonia and bleach) are mixed the gas given off is chlorine gas. The amount of this toxic inhalation hazard (TIH) gas produced is seldom more than irritating unless it is detonated in a small enclosed area. A drain cleaner bomb produces hydrogen gas which is flammable, but the main risk is being sprayed by the caustic drain cleaner. Other chemicals produce different hazards.

I want to be careful not to overly minimize the potential chemical hazards associated with these devices, but they are not typically life threatening. Actually, the case can be made that the person assembling the device is at more of a danger of chemical exposure than people in the general area where the device goes off. Of course, no one should handle these devices if they are found without extensive protective clothing and specialized training.

Chemical Explosives

There is a significant portion of the population that over reacts whenever the word ‘chemical’ is used to describe something. Their visceral reaction is due, in large part, to a comprehensive misunderstanding of chemistry; they equate ‘chemistry’ with all sorts of horrors perpetrated upon humanity by multi-national chemical companies.

Take for example the term ‘chemical explosives’; all explosives are chemical explosives (okay an argument could be made for excluding nuclear bombs). They either require a chemical reaction to produce gasses that that in turn produce pressure or they undergo a phase change (from solid or liquid to gas) that results in the increase in pressure. In many cases the reactions are fast oxidation reactions that we generically call fire.

The True Import of this Chemical Bomb Attack

The explosives used in this case do not produce a great deal of energy and any damage is very localized, barely being enough to damage a mail box. In fact, most law enforcement personnel encounter these devices in mailboxes; a common suburban/rural student prank.

While this particular attack was made upon a ‘political’ target, it is very likely that this was a juvenile prank rather than a political attack on the protestors. If it was a political attack, or even a politically motivated prank, it substantially backfired (as such attacks usually do) in that it provided the protestors with some sympathetic press coverage.