"
Seat belts, pff! They kill more people than they save!"
"
That's not true, you're thinking of airbags!
-
Homer and
Lisa Simpson
A nice idea in theory; you're in a
crash, and before your head snaps forward on your neck, a nice soft bag comes up to gently cushion your
skull, then disappears immediately so you can see to still control the
car.
Airbags deploy in under a quarter of a second, and when used in conjunction with a
seat belt they can be effective in staving off
whiplash and other head injuries for the
average person. Note I said 'average person'. Most people are not average, and in cases where the driver (or passenger) is shorter than what the
engineers of the system have decided, fatalities can occur from
airbag deployment. Of the deaths that have been attributed to airbags, most of them were short adults and children.
The airbag is usually activated when crashing at speeds of 25
km/h or over, and should only activate in front or rear collisions (A bag inflating at speeds toward your face is of no use if your car is hit side on). Exceptions to this are cars produced by companies who consider themselves to be formost experts in safety; like
Volvo, whose newer cars have over twenty airbags for all passengers. This is just
stupid, and honestly, they should spend more time making a more controllable car than filling it with
gimmicky
safety features.
Airbags are designed to
deflate immediately (If you want a nice, air filled pillow, get some
Fill-Air), the theory being that after the initial impact, then car will most likely still be moving, and the driver will be able to control the car better (to avoid a worse accident) if he can see.
Good idea? Yes, but let's examine what happens: An airbag inflates at around 400km/h. This is fast enough to break your nose, cause other serious facial injuries, or even cause death. All of which has been known to happen. There is usually also a lot of dust released with the airbag, due to the installation process and the time between the car being made and the time the airbag is used. Also depending on how the driver's holding the wheel his hands/arms may get broken. This is worse than a
punch in the face, so do you think you'd still be in a good state to steer a car and make decisions about the road? I wouldn't.
Bullbars have been known to cause adverse airbag behaviour, upsetting the timing device and causing the airbag to operate either too late or too early. I laugh at the people in their
Toorak Tractors.
Summing up, in no way would I actively seek out a car with airbags. If I did buy a car with them, I would probably ask the
dealership if they could be removed.
Note: No legislature exists at the moment decreeing that airbags are standard (although some car manufacturers insist on making them standard among some of their models).
Passive safety features are standard. Airbags are classified as active.
For those chemically minded, here is the three step
chemical reaction that inflates airbags, gathered from
http://www.madsci.org/posts/archives/aug99/934263277.Ch.r.html
This initial reaction forms sodium and hot nitrogen gas which inflates the
airbag.
2 NaN3 —> 2 Na + 3 N2
The sodium byproduct of the first reaction and the potassium nitrate
generate additional nitrogen in the secondary reaction.
10 Na + 2 KNO3 —> K2O + 5 Na2O + N2
And finally the previous two reactions leave potassium oxide and sodium
oxide to react with the third component of the mixture, silicon dioxide,
forming alkaline silicate "glass".
K2O + Na2O + SiO2 —> alkaline silicate
As you can see, the reactions in steps 1 and 2 release a great deal of
nitrogen gas. It is this hot nitrogen gas that fills the airbag. The
potentially harmful sodium created in step 1 combines with potassium
nitrate in step 2 to produce more nitrogen, potassium oxide, and sodium
oxide. The final result is nitrogen gas and alkaline silicate powder. The
sodium produced in step 1 may also react with moisture, temporarily forming
sodium hydroxide. Because these reactions occur so rapidly, the multiple
steps in the reaction are in reality occurring simultaneously.