SHEPARDSON: Right. The issue is the propellant in the airbags, the material that actually explodes the airbag into your face, you know, milliseconds after sensors detect a crash is about to happen or has happened, in some cases is damaged and as a result - and what investigators believe is that's mostly linked to high humidity areas where - so in other words, after being exposed to humidity, they're more likely to have defects and as a result rather than simply expand, send this shrapnel into passengers in the vehicles.
GREENE: So this is not part of the actual bag itself? This is like, a piece of the thing that makes the bag explode actually exploding itself and spraying shrapnel at people.
SHEPARDSON: That's right. And also metal parts of the airbag around it. So no it's - you can imagine, it's a very violent incident and it's resulted in serious injuries, as well. I mean, people having - losing eyes or serious lacerations, other cuts. So it's not anything to not take seriously, for sure.So sodium azide is the propellant for air bags, right? So I have a theory that the humidity problems is letting water into the azide compartment and making hydrazoic acid... which is quite explosive/shock sensitive. Readers, what do you think?
(Of course, if the airbags turn out to use another compound (like the nitroguanidines talked about in the Wikipedia entry), then my theory is falsified.)