Writers are constantly looking for cool poisons. I would suspect that about half the questions I receive from writers deal with poisons, usually looking for one that is cool, odd, or difficult to trace. Sodium azide is one of those.
Writers often look to the real world for story ideas. A recent case at a Harvard lab is one that might be useful. Unfortunate for those who became ill, but useful in the world of fiction. It seems that six Harvard medical researchers drank some coffee that was contaminated with sodium azide. All became ill with symptoms that range from dizziness to loss of consciousness. Fortunately none of them died. The question that always arises in such workplace exposures is whether this was accidental or intentional. Apparently an investigation is ongoing.
In the fictional world, my friend Kathleen Antrim used sodium azide in a clever way to off a US senator in her excellent book Capital Offense.
Sodium azide is an odorless white solid that easily dissolves in water or other liquids. When dissolved, it releases a pungent-odored toxic gas and inhalation of this gas can lead to poisoning. It can also be ingested and has the unusual property of rapidly absorbing across the skin. Simply touching the compound or having the liquid it is dissolved in splashed on you could lead to poisoning. This means lab workers who use this compound must be very careful but for fiction writers it offers a world of potential plot events.
Sodium Azide is often discussed in the same sentence with cyanide. Even though they are distinctly separate chemicals, they have many properties in common. They can enter the body by ingestion, inhalation, or through the skin. Both interfere with the ability of the cells within the body to use oxygen and it is this interruption that leads to rapid death. The symptoms of exposure to either of these compounds are similar and might include: chest pain, shortness of breath, dizziness, headache, rapid heartbeat, nausea and vomiting, a low blood pressure with shock, loss of consciousness, sometimes seizures, and death.
Writers are often looking for toxins that mimic a heart attack and, like cyanide, sodium azide fits the bill. The victim would develop chest pain, shortness of breath, become weak and dizzy, collapse, and die. Exactly as would happen in a major heart attack that resulted in sudden death. Since neither cyanide nor sodium azide show up on a routine drug screen, the medical examiner must have a suspicion that such a chemical was involved before he would go to the time and expense of testing for it. With cyanide the medical examiner might notice the bright red color of the blood, the skin, and the internal organs of the victim, a coloration that is due to a chemical reaction between the cyanide and the hemoglobin found within the red blood cells. Sodium azide has no such reaction and so the bright red color is not present. Your sleuth will need some other reason to persuade the ME to do the testing, but that’s what storytelling is all about.