What’s Inside an Automotive Air Bag: The Ingredients That Make It Work

Most airbags inflate using nitrogen gas produced in milliseconds by a small pyrotechnic charge—today typically azide‑free fuels such as guanidine nitrate—while older systems often used sodium azide with potassium nitrate and silica; some modules instead release stored inert gases like argon or nitrogen. Beyond the inflating gas, an airbag system includes an igniter, oxidizers/catalysts, filters and coolants, and a nylon fabric bag often dusted with talc or cornstarch. Here’s how those ingredients differ by inflator type, why the mix evolved, and what you might notice after deployment.

How an air bag inflates

Crash sensors signal an electronic control unit, which fires a tiny explosive “squib” (igniter). That ignites a solid propellant (or opens a valve on a pressurized cylinder), rapidly generating gas to fill the fabric bag. The entire sequence typically takes 20–40 milliseconds, with filters and coolants tempering the hot gases before they enter the bag.

Key ingredients by inflator type

Pyrotechnic inflators (modern, azide‑free)

Most current frontal, side, and curtain airbags use a solid propellant formulated to rapidly generate mostly nitrogen gas while limiting toxic byproducts. These systems rely on a blend of fuels and oxidizers, plus an initiator.

• Fuels (gas generants): guanidine nitrate, nitroguanidine, and nitrogen‑rich heterocycles such as 5‑aminotetrazole and other tetrazoles/triazoles.
• Oxidizers/catalysts: commonly basic copper nitrate; others can include potassium nitrate or strontium nitrate, formulated to control burn rate and temperature.
• Initiator (squib/primer): a small charge that may contain lead styphnate/lead azide or lead‑free alternatives such as diazodinitrophenol (DDNP), plus fuels/oxidizers to ensure reliable ignition.
• Binders, plasticizers, and stabilizers: proprietary additives that hold pellets together and enhance shelf life and combustion stability.
• Filters and coolants: layered steel mesh, ceramic or sintered metal elements that trap particulates and cool the gas before it enters the bag.

Together, these ingredients produce a large volume of relatively cool gas—primarily nitrogen, with some water vapor and carbon dioxide—while minimizing corrosive or toxic residues and visible “smoke.”

Legacy azide inflators (older designs)

Earlier airbags commonly relied on sodium azide-based propellants; the chemistry is effective but sodium azide is acutely toxic in manufacturing and disposal, so the industry shifted away from it.

• Sodium azide (NaN3): the primary gas generant that decomposes to nitrogen and reactive sodium.
• Potassium nitrate (KNO3): oxidizer that reacts with sodium to prevent free sodium metal.
• Silicon dioxide (SiO2): reacts with alkali oxides to form stable silicate glass, reducing caustic residues.
• Initiator and filters: similar roles as in modern inflators, with screens to capture particulates.

These mixtures inflate bags effectively but can leave alkaline particulates; they are now largely phased out in new production, though still present in many older vehicles.

Hybrid and stored‑gas inflators

Some modules, especially certain side and curtain airbags, use inert gas under pressure, sometimes augmented by a small pyrotechnic heater to control fill rate and temperature.

• Stored gases: high‑pressure argon, nitrogen, or blends (occasionally with helium) in a sealed cylinder.
• Pyrotechnic booster: a modest charge to warm the gas and shape the pressure curve on deployment.
• Burst discs, valves, and pressure vessels: aluminum or steel hardware that releases gas precisely when triggered.
• Seals and desiccants: control moisture and maintain long‑term stability.

Hybrid and stored‑gas systems provide clean, inert inflation with very low particulate output, which is useful where occupant proximity or rapid, controlled filling is critical.

Non‑chemical materials you’ll find

Beyond propellants and gases, an airbag module includes engineered materials that shape, deploy, and protect the bag and occupant.

• Airbag fabric: tightly woven nylon 6,6 (often silicone‑ or neoprene‑coated) to handle heat, abrasion, and permeability.
• Surface powders: cornstarch or talc applied to the bag so folded layers don’t stick and the bag deploys smoothly.
• Inflator housing and screens: metal canisters and mesh packs that meter, cool, and filter the gas.
• Wiring, connectors, and sensors: crash sensors, control electronics, and inflator connectors engineered to automotive safety standards.

These materials ensure that gas delivery is controlled, the fabric resists heat and tearing, and the system remains reliable over years of service.

What’s the “dust” after deployment?

The visible cloud after an airbag deploys isn’t smoke from a fire; it’s mostly fine particulates and water vapor carried in the gas stream. What you see depends on the inflator type and bag preparation.

• Bag powder: cornstarch or talc released from the fabric as the bag unfurls.
• Gas‑generation residues: in modern azide‑free systems, minimal solids; in older azide systems, traces of alkaline particulates (e.g., silicates/carbonates) that can irritate eyes or skin.
• Gases: mainly nitrogen, with some CO2 and water vapor; odor may come from combustion byproducts of the initiator.

Ventilate the cabin after deployment, avoid rubbing your eyes, and rinse exposed skin. Seek medical attention if you experience persistent irritation or breathing difficulty.

Safety, recalls, and environmental notes

Airbag chemistry evolved to reduce toxicity and improve stability. Modern inflators generally avoid sodium azide and, in many designs, avoid pure ammonium nitrate generants. The Takata recalls centered on ammonium nitrate propellants that degraded with heat and humidity, leading to rare but severe inflator ruptures; many vehicles worldwide are still under recall campaigns. Vehicle owners should check their VIN with their national safety authority or automaker to confirm recall status and obtain free repairs. Airbag modules are hazardous waste if undeployed and should be handled and recycled by certified technicians.

Summary

Airbags inflate using either a fast‑burning solid propellant (now typically azide‑free compounds like guanidine nitrate, with oxidizers and an igniter) or by releasing stored inert gases (argon/nitrogen) in hybrid systems; older units often used sodium azide with potassium nitrate and silica. Supporting ingredients include filters and coolants, a nylon fabric bag treated with talc or cornstarch, and electronic initiators. The result is a rapid burst of mostly nitrogen gas that fills a durable fabric cushion to protect occupants during a crash.

Do they still use sodium azide in airbags?

No, sodium azide is not widely used in modern automotive airbags anymore, having been replaced by less hazardous alternatives like guanidine nitrate or ammonium nitrate to avoid its toxicity. While a previous generation of airbags used sodium azide to produce nitrogen gas for inflation upon impact, this practice declined due to its hazardous nature and the issues with its reactive byproducts, such as sodium hydroxide, which can be irritating or harmful. 
Here’s a closer look at the chemical and its history in airbags:

• How it works: In a crash, sodium azide reacts with an igniter to rapidly decompose into harmless nitrogen gas (which inflates the bag) and reactive metallic sodium. 
• Safety concerns: The reactive sodium is then quickly converted into less toxic compounds by other chemicals, like potassium nitrate and silica, to prevent harm. However, some sodium hydroxide dust can still be released, causing mild irritation. 
• Shift to alternatives: The toxicity of sodium azide and the dangers of its byproducts led manufacturers to switch to other chemicals, like guanidine nitrate. 
• Exceptions: Sodium azide may still be used in other applications, such as aircraft evacuation slides or in labs as a preservative. 

What does sodium azide do to the body?

At low doses, azide causes dizziness, nausea, vomiting, and restlessness. At high doses, it causes seizures, hypotension, metabolic acidosis, coma, and respiratory failure. Symptoms occur within minutes of exposure.

What chemicals are in air bags?

sodium azide
Air bags are inflated by nitrogen gas which is produced by the highly toxic chemical, sodium azide. However, the sodium azide is completely consumed by this reaction. After deflation of the bag some irritant dusts (including sodium hydroxide) are released.

Are airbag fumes harmful?

Lung Damage: Just as the chemicals contained inside airbags can leave chemical burns on the skin, these same chemicals can harm the lungs if inhaled. Airbags that sustain cuts may allow gaseous chemicals to escape directly into an accident victim’s face, making inhalation of the fumes difficult or impossible to avoid.