Can airbags cause burns?

By Stuart Johnson

There have been a relatively small number of cases reported where the deployment of airbags have caused burns on the skin of occupants involved in an accident.

These burns are usually the result of gas and powder residue from the airbag after it has been deployed in an accident, coming into contact with an accident victim’s skin. The residue is very alkaline in composition (although manufacturers have taken steps to reduce the alkalinity), and the extreme alkalinity can cause burns.

 In other cases there can be abrasion burns when the airbag comes into contact with the occupant’s body.

 A third cause can be heat burns, because the gas (nitrogen) that inflates the airbag momentarily reaches very high temperatures, needed to inflate the airbag. This gas then escapes  through perforations in the airbag designed for the bag to deflate with seconds after deployment. If an occupant is unlucky, he or she may come into contact with the area of the airbag where the gas is designed to escape the bag, and these temperatures may still be high. This normally happens when an occupant sits too close to an airbag, or is not wearing a seat belt!

Where airbags are located…

Airbags are fitted into various locations in a modern car’s interior. Some modern, expensive  cars have up to 10 airbags located in areas designed to protect you from a number if collision possibilities.

Typically, less expensive cars have a driver’s airbag located in the steering wheel, and a front passenger airbag located in the dashboard on the passenger side.  Very cheap cars have only a driver’s airbag,  or no airbags!

How airbags work

In the case of a collision, a sensor that detects very sudden deceleration ( such as when your car strikes another car or a solid object like a wall) sends a signal to a canister fitted to the base of the airbag.

This signal causes  a small pellet of a substance called sodium azide, located in the canister,  to be ignited. The resultant explosion causes a gas called nitrogen to be produced, and this rapidly expanding gas (with an initial  temperature of up to 500 degrees C) fills up the airbag, which pops through the protective covering of the steering wheel centre,  dashboard, or other location such as the window or seat area.

It is expelled   at great force into the bag , and forms a protective balloon of the airbag, which is made out of a nylon-type substance.

It all happens very, very fast

This deployment of the inflated airbag takes a mere 0,03 seconds, a speed necessary to provide protection in a crash. Within a second of full inflation, the bag already starts to subside, as the gas inside the airbag  is allowed to escape through vent perforation areas, located in the area close to the base, where the propellant canister is located.

When initial inflation occurs, the gas is often accompanied by fine powder which  can be expelled through the tiny airbag vent holes, and this very alkaline  powder can cause burning if it lands on unprotected skin.

Burn cases  reported

According to experienced paramedic Philip Hull, who has run many road-side medical evacuation teams at peak traffic periods in South Africa, burn cases still occur due to airbag deployment, but are of a relatively minor nature. They take the form of small spot-burns, due to the hot gas residue, which often also contains a form of fine  powder substances, landing on the skin.

More serious can be airbag impact injuries, where occupants have been struck by the full force of the airbag, due to incorrect seating placement, or by driving without buckling up a seat belt. For this reason, babies and small children should be seated in the back of a vehicle.

But airbags have saved many lives

However, Hull stresses that the injuries caused by airbags are far outweighed by the protective assistance that airbags give in an accident. An injury sustained by striking a solid object such as a steering wheel, window frame or dashboard would be far more severe.

Indeed, it is estimated that since their widespread introduction which began some 30 years ago ( they first appeared in a very small number of US cars in the 1970s) airbags have reduced road accident fatalities by some 30 per cent.