This is a little bit out of the terrorism realm, but there is an interesting article about ‘homemade chemical bombs’ in the most recent CDC Morbidity and Mortality Weekly Report. These really are not improvised explosive devices, they don’t have that kind of power, but they do cause casualties in middle-America on a fairly routine basis.
Generally speaking these ‘devices’ are not truly explosives because fire is not involved. Some sort of simple chemical reaction (or phase change) causes the production of a gas. The amount of gas produced in a closed container many cause a catastrophic failure of the container, accompanied by a loud bang (or soft boom) and frequently a visible gas cloud. That gas cloud is usually responsible for the more serious injuries associated with these devices because of the toxicity of the gas.
There is little authorities can do to prevent teenagers (chronological or developmental) from constructing these devices. The components are readily available in the home or hardware store. The more effective of these devices (measured by the sound of the boom or size of the gas cloud) do require slightly more expensive chemicals, but these can usually be obtained from high school or college chemical store rooms.
Frequently these ‘bombs’ are made in plastic soda bottles so they have a relative low probability of causing blast or shrapnel type injuries. When made in glass containers or PVC pipe there is a low-level shrapnel (Purists please don’t’ complain that ‘Shrapnel’ comes from a specific type of Civil War era munition, common usage includes flying pieces of bomb casings of any type) hazard, but only very close to the detonating device.
Having played with these things in my youth (long before the Internet we had Headly’s Formulary or the Anarchist’s Cookbook) I can testify that most of the people injured by these devices are the ‘bombers’. These devices typically don’t include fuses; they rely on the speed of chemical reactions and the quality of the ‘bomb case’ to determine when they will actually ‘detonate’; too many variables for the limited attention span of teenagers to perfect.
They are potentially dangerous, the danger increasing as you get closer to the device. The biggest danger to first responders is not being able to tell in advance what the resulting chemical cloud will be. The CO2 cloud from a ‘dry-ice’ bomb is relatively non-hazardous; the chlorine gas from a bleach-bomb can be toxic to severely irritating depending on the amount produced and local ventilation conditions.
There is one type of these chemical bombs that is slightly more dangerous and that is because it produces a very flammable hydrogen gas-cloud. The initial detonation of these ‘aluminum’ bombs is the typical gas pressure reaction, but the resulting gas cloud (depending on local conditions) can result in a secondary explosion producing fire and flying debris.
All first responders and emergency medical personnel should read the CDC article.