Wednesday, 19 August 2015

boom! boom!

When I heard news, a few days ago, of the explosions in the Chinese port city of Tianjin, I was immediately reminded of a similar incident that took place in West, Texas, a little more than two years ago, in April 2013. Both involved residential areas being located far too close to facilities where dangerous chemicals were being stored, and in both cases a disproportionate number of those killed were firefighters. In neither case did these men have any idea what they were up against.

In the US incident, more than 245,000 kilograms of ammonium nitrate exploded while the fire crews were responding to a small fire that had broken out at the storage facility, yet nobody had thought to warn them in advance that this highly explosive material was there. Nobody—other than the company that owned the facility—knew it was there.

The identity of the chemicals that exploded in Tianjin is much less certain, although it almost certainly included an accelerant (oxidizing agent) like ammonium nitrate. The purported presence of sodium cyanide may just have been the kind of scare story that inevitably spreads around whenever there is a shortage of hard information, although a British chemical expert who appeared on BBC Radio 4’s Today program did suggest that sodium metal was present. I think we can discount this hypothesis, because sodium does not occur as a metal in nature, and as far as I can tell the only use for this element is to have tiny slivers dropped into large tanks of water by chemistry teachers to demonstrate to their pupils the violent reaction that occurs. This would not justify storing enough of the metal to cause the explosions.

Perhaps the most realistic assessment of the chemicals involved that I’ve seen is a combination of calcium carbide, potassium nitrate (saltpetre) and ammonium nitrate. Calcium carbide, when mixed with water, produces the highly flammable gas acetylene, while the other two are both powerful accelerants (saltpetre was used in the original Chinese recipe for gunpowder) as well as being used as fertilizers. A ready supply of oxygen to feed an incipient fire is obviously a recipe for disaster.

However, the most striking similarity between the two incidents is not the presence of accelerants but the secrecy involved. Nobody but the employees of the West Fertilizer Company knew that a huge quantity of ammonium nitrate was being stored on the firm’s premises, while nobody will admit to knowing precisely what was being stored in the warehouse in Tianjin. The juxtaposition is striking: defenders of the American company would probably cite commercial confidentiality, while the Chinese Communist Party will probably invoke state secrecy laws if anyone has the temerity to probe too deeply. In other words, despite the ideological competition between the ‘land of the free’ and the ‘middle kingdom’, politicians in both countries couldn’t care less about ordinary citizens.

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