and How They Changed The World Around Us

Discovery of the Airbag

John W. Hetrick, a retired industrial engineering technician, was the man behind the invention of the airbag. The inspiration for his invention had to do with one of his own experiences. One day, while he was driving on the road with his wife and 7 year old daughter, they were involved in an accident. Fortunately they survived, but this scared John as he always worried about the safety of his family and others, so he wanted to find a way to reduce the effects of a car crash. Little did he know, he would end up designing one of the most important advances in automobile safety today.

Hetrick, received a patent, or a license, in 1953 for what he called a "safety cushion assembly for automotive vehicles." His U.S. Patent No. 2,649,311 was the first prototype for today's modern airbags.

Chemical Reaction

The chemical at the heart of the air bag reaction is called sodium azide. The formula for this chemical is NaN3. Under normal circumstances, the sodium azide is quite stable. If heated, though, it will decompose. In this reaction, Sodium Azide decomposes into Sodium and Nitrogen gas. The chemical equation 2 NaN3 --> 2 Na + 3 N2 describes exactly how it decomposes. The second product of the above reaction is N2, which is also known as nitrogen gas. A handful of sodium azide will produce 67 liters of nitrogen gas--which is enough to inflate a normal air bag. chemical at the heart of the air bag reaction is called sodium azide, or NaN3

How it works

What prompts an air bag to inflate by way of this reaction? There are sensors in the front of the automobile that detect a collision. These sensors send an electric signal to the canister that contains the sodium azide and the electric signal detonates a small amount of an igniter compound. The heat from this ignition starts the decomposition of the sodium azide and the newly formed nitrogen gas fills the air bag. This reaction, from the time the sensor detects the collision to the time the air bag is fully inflated, is only 30 milliseconds, or 0.03 seconds long. Some 50 milliseconds after an accident, the car's occupant hits the air bag and its deflation absorbs the forward-moving energy of the occupant.

A second later, the gas quickly dissipates through tiny holes in the bag, thus deflating the bag so you can move.

Impacts on society

Airbags have played a big role in changing our society for the better. To date, statistics show that airbags reduce the risk of dying in a direct crash by about 30 percent. Since the invention of the airbag, many lives that could have been lost in car crashes were able to be saved.
Big image


  • BENEFITS- The goal of an airbag is to slow the passenger's forward motion as evenly as possible in a fraction of a second would restrain automobile drivers and passengers in an accident, whether or not they were wearing their seat belts.

  • RISKS- One of the chemicals that sodium azide decomposes into is Na, or sodium. Sodium is a very reactive metal that reacts rapidly with water to form sodium hydroxide. This new chemical is poisonous and would be quite harmful if it got into your eyes, nose or mouth. Another risk of airbags is that if you are too close to it, there is a possibility of fatality due to the pressure. Researchers have determined that the risk zone for driver airbags is the first 2 to 3 inches (5 to 8 cm) of inflation. An airbag can seriously injure or even kill an unbuckled child who is sitting too close to it or is thrown toward the dash during emergency braking. It also has some risks towards the environment. The vast majority of airbags in cars are never deployed within the lifetime of the car. These unused airbags are flattened and recycled at the end of their lifetime, and they are never removed from the cars. This can be hazardous, because these airbags still contain sodium azide, whose presence during the automobile-recycling process endangers workers, and can damage recycling equipment and the environment

Interesting Facts

  • The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or door.
  • The sensor is the device that tells the bag to inflate. Inflation happens when there is a collision force equal to running into a brick wall at 10 to 15 miles per hour (16 to 24 km per hour). A mechanical switch is flipped when there is a mass shift that closes an electrical contact, telling the sensors that a crash has occurred. The sensors receive information from an accelerometer built into a microchip.
  • The powdery substance released from the airbag is regular cornstarch or talcum powder, which is used by the airbag manufacturers to keep the bags lubricated while they are in storage.
  • Seat belts are still completely necessary because airbags work only in front-end collisions occurring at more than 10 mph (6 kph).


By: Hiba Bhutta