I'am an Airbag

How does an airbag work?

Airbags are inflated by the nitrogen gas generated during the combustion of the special chemical mixture that fills the gas generator cartridge operating the airbags.

The process takes place in about 40 msec as follows: the slowdown sensor in the starter electronics gives an impulse to the airbag's pyrotechnic system, which ignites the compound. Nitrogen gas is formed during the chemical reaction taking place during the combustion of this material. 

The sodium azide used in airbag cartridges decomposes into harmless components during the deployment of the airbag. However, sodium azide is to be treated as hazardous waste, as it does not decompose by itself. 

The afterlife of an airbag

Fortunately, the vast majority of car airbags never explode during the lifetime of the vehicle. Typically, cars are compressed and recycled at the end of their lives, usually with the airbags in them. This is dangerous, because these airbags still contain sodium azide, which endangers the health of the people involved in the car's recycling process, as well as the environment.  Sodium azide can react in various ways during the recycling process. The first step in the process is the compression of cars. After a car is compressed, one cannot see if it has an airbag. If the NaN3 storage tank is damaged during the compression, potentially mutagenic and carcinogenic NaN3 may be released into the environment. (Let’s keep in mind that the maximum concentration of NaN3 at the workplace is 0.2 mg/ m3 of air.) The next step in recycling cars is shredding, which enables the different types of metals to be separated and recycled. The sodium azide released during this process can contaminate the steel, iron and non-ferrous metals recovered at this stage. Of greater concern is, however, the high amount of heat and friction generated by the shredder. NaN3 reacts explosively at high temperatures; therefore, there is a risk of inflammation when the airbags pass through the car shredder. This danger is exacerbated when the sodium azide comes into contact with the heavy metals from the car, such as lead and copper, because these can react as volatile explosives. Parts of the car can also go through a wet shredder. Another danger emerges at this point, because when NaN3 is dissolved in water, it can form a hydrazoic acid (HN3), which is highly toxic, volatile and explosive.

What can we do?

  1. We shouldn’t be afraid of airbags, because they can save lives!
  2. We should be aware of the fact that we can take care of our environment through mindfulness and cooperation.
  3. We shouldn’t just keep nodding, but instead do something for our environment!

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