Sodium azide (NaN₃) is a rapidly acting, potentially deadly chemical that exists as an odorless white solid. When it is mixed with water or an acid, sodium azide changes rapidly to a toxic gas with a pungent (sharp) odor. It also changes into a toxic gas when it comes in contact with solid metals (for example, when it is poured into a drain pipe containing lead or copper). The odor of the gas may not be sharp enough, however, to give people sufficient warning of the danger.

Sodium azide is best known as the chemical found in automobile airbags. An electrical charge triggered by automobile impact causes sodium azide to explode and release nitrogen gas inside the airbag. The Center for Disease Control has received no reports of sodium azide exposure following automobile airbag deployment.

Sodium azide is also used as a chemical preservative in hospitals and laboratories, in agriculture (farming) for pest control, and in detonators and other explosives.

Toxic effects

The seriousness of poisoning caused by sodium azide depends on the amount, route, and length of time of exposure, as well as the age and preexisting medical condition of the person exposed. Breathing the gas that is formed from sodium azide causes the most harm, but ingesting (swallowing) sodium azide can be toxic as well. The gas formed from sodium azide is most dangerous in enclosed places where the gas will be trapped. The toxic gas quickly disperses in open spaces, making it less harmful outdoors. The gas formed from sodium azide is less dense (lighter) than air, so it will rise.

Azide anions prevent the cells of the body from using oxygen, inhibiting the function of cytochrome oxidase by binding irreversibly to the heme cofactor in a process similar to that of carbon monoxide. When this happens, the cells die. Sodium azide is more harmful to the heart and the brain than to other organs, because the heart and the brain use a lot of oxygen.

People exposed to a small amount of sodium azide by breathing it, absorbing it through their skin, or eating foods that contain it may have some or all of the following symptoms within 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 by any route may cause these other health effects as well:

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

Showing these signs and symptoms does not necessarily mean that a person has been exposed to sodium azide. Survivors of serious sodium azide poisoning may have heart and brain damage.

Treatment

Sodium azide poisoning is treated with supportive medical care in a hospital setting. No specific antidote exists for sodium azide poisoning. The most important thing is for victims to seek medical treatment as soon as possible.