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First, the basics.
Sodium azide (NaN3) is an odorless white solid that reacts violently with water, acid, or solid metal (lead or copper, for instance). It is also explosively reactive, and finds commercial use in a number of ways, most commonly as the chemical found inside automobile airbags. It is also used as a preservative in hospitals and labs, an agricultural biocide, and as a detonator in explosives.

How does it find its commercial use?
As already stated, sodium azide is used primarily as a detonator for explosives (for the purposes of this writeup, airbags, which are designed to inflate with gas within about sixty milliseconds of an impact, are also considered explosives). This usage is due to the chemical’s molecular structure, which is expressed as something like this:

[N==N==N]-  Na+

The azide ion (the three nitrogen molecules) is remarkably unstable, and therefore reacts readily with water, acid, or metal to form the much more stable nitrogen gas (only two bonded nitrogen molecules instead of three), providing the force for explosive reactions utilizing sodium azide.

In addition to all of this, sodium azide is also incredibly toxic, reacting to form a gas that is lighter than air and prevents the body from using oxygen properly. The gas given off when it reacts has a sharp odor, which may not be enough to give sufficient warning of its presence. Inhalation of the gas causes organ damage in general, but tends to cause more damage to the heart and brain, because these two organs use a lot of oxygen to function.

So what other health risks does it pose?
Exposure can occur through three methods: absorbing it through your skin, eating foods that contain it, or breathing it in (either in dust or gas form). Exposure to even a small amount of this chemical may cause some or all of the following symptoms, with an onset time of a few minutes:

  • Rapid breathing
  • Restlessness
  • Dizziness
  • Weakness
  • Headache
  • Nausea and vomiting
  • Rapid heart rate
  • Red eyes (gas or dust exposure)
  • Clear drainage from the nose (gas or dust exposure)
  • Cough (gas or dust exposure)
  • Skin burns and blisters (explosion or direct skin contact)

Exposure to a large amount of sodium azide may cause, in addition to the symptoms listen above:

  • Convulsions
  • Low blood pressure
  • Slow heart rate
  • Loss of consciousness
  • Lung injury
  • Respiratory failure leading to death

Death from exposure to a large amount of sodium azide will usually occur within thirty minutes, a toxicity on par with sodium cyanide. The risks presented by even small amounts of sodium azide are great, and yet its use is maintained in automobiles, hospitals, and agriculture. This fact may or may not stem from lack of consumer awareness about the dangers it can pose. Either way, its usefulness in these applications can not be denied.

Sources:
http://www.bt.cdc.gov/agent/sodiumazide/basics/facts.asp
http://www.alanwood.net/pesticides/sodium_azide.html
http://www.chm.bris.ac.uk/webprojects2002/shillings/sodium_azide.htm

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