What Happens When an Airbag Goes Off

When an airbag deploys, crash sensors detect a severe impact, a pyrotechnic inflator fills the airbag with gas in about 20–40 milliseconds, the bag bursts through its cover to cushion you, then quickly vents and deflates. It’s loud, smoky-looking, and can cause minor abrasions, but it dramatically reduces the risk of serious injury when used with a seatbelt.

How the Car Decides to Fire the Airbag

Modern supplemental restraint systems (SRS) watch for rapid deceleration, impact direction, and occupant status. Accelerometers and pressure sensors feed the airbag control unit, which uses algorithms to determine whether and which airbags should deploy. For frontal airbags, the decision typically corresponds to a crash roughly equivalent to hitting a rigid barrier at about 12–16 mph (20–25 km/h) for a belted adult, but the exact thresholds vary and account for crash angle, vehicle speed change, and seatbelt use. Side and curtain airbags trigger on different cues, such as rapid door intrusion or side pressure spikes, and curtains may also deploy in rollovers.

The Split-Second Timeline

The following sequence outlines what happens from impact to deflation during a typical deployment, helping you understand the speed and purpose of each step.

1. 0–10 ms: Sensors detect rapid deceleration or side pressure change; the airbag control unit verifies it’s a deployable crash.
2. 10–20 ms: The inflator ignites a small charge; gas (often nitrogen from pyrotechnic propellants or stored/compressed gas) floods the airbag.
3. 20–40 ms: The bag bursts through its cover, unfolds, and inflates fully to meet the moving occupant.
4. 40–120 ms: The occupant loads the bag; vents and fabric porosity allow controlled deflation to absorb energy.
5. Up to several seconds: Curtain airbags may stay inflated longer (often up to ~6 seconds) to protect during rollovers and multiple impacts; frontal bags deflate quickly.

This rapid sequence lets the airbag be fully ready just as you contact it, then get out of the way so you can breathe and exit.

What You’ll Hear, See, and Feel

People often mistake the sights and sounds for fire or smoke. Here’s what typically happens to the senses in a deployment.

• Sound: A very loud bang, comparable to a gunshot (around 140 dB at the source), which can cause temporary ringing.
• Sight: A flash from the igniter and a cloud that looks like smoke—usually powder (talc or cornstarch used to help the bag deploy) mixed with gas byproducts.
• Smell: A sharp, acrid odor from the inflator chemicals; unpleasant but brief.
• Sensation: A strong shove from the bag; possible minor abrasions or “burns” from friction and hot gases.

While startling, these effects are normal and not a sign of fire; the dust can irritate eyes and lungs, especially for people with asthma.

How Airbags Work With Seatbelts

Airbags are supplemental—they are designed to be used with seatbelts. Pretensioners snap belts tight just before the bag deploys, reducing forward motion so the airbag can catch you effectively. Without a belt, you can hit the bag too early and too hard, increasing injury risk. Occupant sensors and multi-stage inflators tailor deployment force based on seating position, weight classification, and crash severity.

Different Airbag Types and Their Roles

Vehicles use a suite of airbags, each tuned for specific crash scenarios and body areas.

• Frontal airbags: Protect head and chest in head-on and some angled impacts; deploy quickly and deflate fast.
• Side thorax airbags: Emerge from the seat or door to shield the ribs and abdomen from intrusion.
• Curtain airbags: Drop from the headliner to protect heads in side impacts and rollovers; often remain inflated longer.
• Knee airbags: Help control lower-body motion and reduce leg injuries in frontal crashes.
• Rear-seat airbags (in some models): Provide head/chest protection for back-seat occupants.
• Center airbags (in newer vehicles): Help prevent occupant-to-occupant head contact in side crashes.

Together, these systems create a protective “cocoon,” with timing and inflation tailored to the specific impact.

What’s Inside: Gases and Powders

Older inflators often used sodium azide propellant, which produced nitrogen but could leave alkaline residues; modern designs favor guanidine nitrate or hybrid/compressed-gas inflators that produce mostly nitrogen and inert byproducts. The visible “smoke” is typically deployment powder (talc or cornstarch) plus minor combustion residues. Skin and eye irritation is possible, and hot surfaces can cause mild burns, but serious chemical injury is uncommon in modern systems.

Immediate Steps After an Airbag Deploys

After the shock of deployment, taking the right actions can protect your health and preserve evidence.

1. Check yourself and passengers for injuries; expect ringing ears and minor burns or abrasions.
2. If safe, move the vehicle out of traffic; otherwise, switch off the engine and turn on hazard lights.
3. Exit the vehicle if you can do so safely; avoid touching hot airbag surfaces.
4. Call emergency services, especially if any injuries, smoke, fluid leaks, or significant damage are present.
5. Avoid rubbing eyes; if irritated, rinse gently with clean water.
6. Document the scene and damage for insurance; note whether multiple airbags or seatbelt pretensioners fired.

Do not continue driving with deployed airbags; systems and steering components may be compromised, and visibility can be impaired.

Repair, Replacement, and Data

Airbags are single-use. After deployment, the airbag module(s), inflators, control unit (which may lock after a deployment), clockspring, steering-wheel or dash covers, and seatbelt pretensioners typically require replacement. Costs often range from roughly $1,000 to over $5,000 depending on the number of components and vehicle model; insurers frequently cover this after a crash. Avoid counterfeit airbags; they may not deploy correctly. Many vehicles store crash data in an event data recorder (EDR) that can be downloaded by authorized technicians or investigators.

Safety Tips to Reduce Airbag-Related Injury

Correct seating and habits make airbags most effective while minimizing injury risks.

• Always wear a seatbelt; keep at least 10 inches (25 cm) between your chest and the steering wheel.
• Use 9-and-3 hand position on the wheel; avoid 10-and-2 to reduce forearm/facial injury from a deploying bag.
• Keep the wheel aimed at your chest, not your face; recline only slightly to maintain proper posture.
• Never put feet on the dashboard; a passenger airbag can cause severe leg injuries.
• Children under 13 should ride in the back seat; never place a rear-facing child seat in front of an active airbag.
• Pregnant occupants should sit as far back as comfortable, belts low across the hips, and keep the wheel away from the abdomen.
• Address airbag warning lights promptly; have recalls (including Takata inflator recalls) completed immediately.

These practices help the SRS work as designed, maximizing protection in a crash.

Risks and Rare Failures

While airbags save lives, they can cause minor injuries such as abrasions, contusions, or temporary hearing changes; serious injuries are rare and often tied to out-of-position occupants or lack of seatbelt use. A small number of vehicles with defective inflators (notably certain Takata ammonium nitrate inflators) have experienced ruptures; if your vehicle is under recall, have it repaired at no cost as soon as possible.

Summary

When an airbag “goes off,” sensors detect a severe crash, a small charge inflates the bag in milliseconds, it cushions you as it vents, and the system then stands down. It’s loud and startling, with powder and an acrid smell, and may leave minor abrasions, but when paired with a seatbelt it dramatically reduces the risk of serious or fatal injury. Sit properly, buckle up, keep children in the back, and address recalls to ensure the system protects you as intended.

Can you fix a car after airbags deploy?

Yes, a car can be fixed after the airbags deploy, but it requires replacing the entire airbag module, other safety components like crash sensors and seat belts, and potentially the dashboard. This can be very expensive, and if the repair cost exceeds the vehicle’s value, the insurance company may declare it a total loss. It is not safe to drive a car with deployed airbags because the safety system is compromised. 
This video explains the process of repairing a car after airbag deployment, including the removal of seat belts and the airbag module: 1m4Lane BlacktopYouTube · Apr 16, 2022
Why Airbag Replacement is Necessary

• One-time use: Deployed airbags cannot be reused; they must be replaced with new units. 
• System components: Beyond the airbags themselves, other crucial safety components like crash sensors, the Supplemental Restraint System (SRS) control unit, and seatbelt pretensioners may need to be replaced or reset. 
• Damage to panels: The panel the airbag was housed behind, such as a dashboard or steering wheel, will also need to be replaced or repaired. 

Why a Car Might Be Totaled

• High cost of repair: Opens in new tabThe comprehensive cost of replacing all necessary components can quickly make repairing the car uneconomical, especially for older or less valuable vehicles. 
• Overall vehicle damage: Opens in new tabThe severe impact that triggers airbags often causes significant structural damage to the vehicle, which adds to the total repair cost and can contribute to a total loss determination. 

This video discusses why a car is considered a total loss after airbag deployment and the factors that influence the decision: 51sAuto Expert John CadoganYouTube · Sep 23, 2022
What to Do After Airbags Deploy

1. Do not drive the car: Opens in new tabThe vehicle is not safe to drive until the entire safety system is restored. 
2. Get a professional assessment: Opens in new tabA qualified mechanic needs to inspect the vehicle to determine the extent of the damage and the cost of repairs. 
3. Contact your insurance company: Opens in new tabThey will assess the damage and decide whether to cover the repairs or declare the car a total loss. 

What happens when the airbag goes off?

When airbags deploy, crash sensors trigger a chemical reaction inside the airbag’s inflator unit, rapidly producing nitrogen gas to inflate the bag with tremendous force in milliseconds. The airbag then deflates through vent holes to absorb the occupant’s energy, acting as a cushion. This rapid, forceful process can cause injuries, such as bruises or abrasions, but it is designed to prevent more severe injuries by creating a buffer between the occupant and the vehicle’s interior.
 
This video shows the process of an airbag deploying in slow motion: 58sAMSOIL INC.YouTube · Jan 29, 2025
The Deployment Process

1. Crash Detection: Sensors detect a severe deceleration, signaling a collision. 
2. Chemical Reaction: The sensor’s signal activates an igniter within the airbag module. 
3. Gas Production: The igniter starts a chemical reaction, often with sodium azide, which produces a large volume of nitrogen gas almost instantly. 
4. Inflation: The gas rapidly fills the airbag, which is folded within the steering wheel, dashboard, or other locations. 
5. Impact and Deflation: The fully inflated airbag impacts the occupant, cushioning their movement, and then immediately begins to deflate through small vent holes to allow for escape and clear the driver’s vision. 

Key Characteristics of Airbag Deployment

• Speed: The entire process occurs faster than the blink of an eye, often within milliseconds. 
• Force: Airbags inflate with significant force to protect occupants from hitting hard surfaces. 
• Deflation: Immediate deflation is crucial to prevent suffocation and allow occupants to exit the vehicle. 
• Dust: The “smoke” or dust sometimes seen after deployment is a nontoxic powder (like starch or talc) used to prevent the airbag from sticking together. 

This video explains how airbags work and the role of gas in inflating them: 53sSabin Civil EngineeringYouTube · Nov 26, 2021
Importance of Seat Belts

• Airbags are most effective when used in conjunction with seat belts. 
• The seat belt restrains the occupant, preventing them from moving too close to the airbag during deployment and being injured by its force. 
• Without a seat belt, an occupant could be thrown into the deploying airbag with greater force, increasing the risk of serious injury. 

What are the symptoms of airbag injury?

Airbag injury symptoms range from minor scrapes, bruising, and burns to more severe conditions like broken ribs, facial fractures, concussions, and internal bleeding. Common symptoms include facial redness and swelling, eye irritation, ear ringing, chest pain, headaches, confusion, and difficulty breathing. It is important to seek immediate medical attention after an airbag has deployed, as some injuries can have long-term consequences if not treated promptly.
 
Facial & Eye Injuries

• Symptoms: Opens in new tabBruising, swelling, abrasions, redness, irritation, changes in vision, or a black eye. 
• Cause: Opens in new tabDirect impact from the airbag and chemical irritants released during deployment. 

Burns & Abrasions 

• Symptoms: Scrapes, friction burns, or chemical burns on the face, chest, or arms.
• Cause: The rapid friction and heat generated by the airbag’s inflation, as well as the chemical components released.

Chest & Rib Injuries 

• Symptoms: Opens in new tabChest pain (especially when breathing deeply), tenderness, swelling, or difficulty breathing. 
• Cause: Opens in new tabSignificant pressure on the chest from the airbag, potentially leading to bruised or broken ribs. 

Head & Brain Injuries 

• Symptoms: Opens in new tabHeadaches, dizziness, confusion, memory loss, loss of balance, or vision problems.
• Cause: Opens in new tabThe violent jolt of the airbag can cause a concussion or traumatic brain injury (TBI).

Neck & Spinal Injuries 

• Symptoms: Stiffness, pain, or a limited range of motion in the neck.
• Cause: The forceful and sudden pressure on the neck and spine during deployment can cause strains, sprains, or, in severe cases, spinal fractures.

Hearing Issues 

• Symptoms: Temporary hearing loss or ringing in the ears (tinnitus).
• Cause: The extremely loud sound of an airbag deploying.

Internal Injuries

• Symptoms: Internal bleeding, dizziness, or fainting. 
• Cause: The force of the airbag can cause blunt force trauma to internal organs, leading to damage and internal bleeding. 

When to Seek Medical Help

• If you experience any symptoms after an accident, it is crucial to seek medical attention right away. 
• Symptoms like severe chest pain, dizziness, difficulty breathing, or persistent confusion warrant immediate medical care. 

Can you still drive a car if the airbags go off?

No, you cannot, and should not, drive a car once the airbags have deployed because the vehicle is no longer safe. The impact required to deploy airbags often causes significant, unseen damage to critical systems, and the airbag system itself will not function again until it’s professionally repaired. Driving a car with deployed airbags is a severe safety risk due to lack of protection in another collision and can also have legal and insurance consequences. 
Why you shouldn’t drive the car

• Compromised Safety Systems: Airbag deployment indicates a serious collision, and underlying structural or mechanical damage can make the car unsafe. 
• Disabled Airbags: Deployed airbags cannot be used again and will not provide protection in a future crash until the entire system is replaced. 
• Visibility and Comfort: Deployed airbags can obstruct your view and make it difficult or impossible to operate the vehicle comfortably. 
• Potential Legal Issues: It may be illegal to drive a vehicle with deployed airbags, and your insurance coverage could be voided if you continue to operate it. 

What to do instead

1. Do not drive the vehicle. Opens in new tabArrange for it to be towed to a certified collision center for inspection and repair. 
2. Have the entire vehicle inspected Opens in new tabfor underlying damage to mechanical components, the frame, and other safety systems. 
3. Contact your insurance provider Opens in new tabto discuss coverage for the repairs, especially if the car is not deemed a total loss.