I forgot the precise composition of the "gunpowder" they used. The powder they used turned out to be not stable and susceptible to moisture creeping in over time into the canister that holds it, combined with poor quality control during manufacturing. It is the metal shrapnel from the exploding canister during an accident which caused the injuries (and death) to people in the affected cars. More company information can be found at the Wikipedia page: https://en.wikipedia.org/wiki/Takata_Corporation Edit: the Takata Wikipedia page mentions ammonium nitrate. The page about this chemical compound explains that it is a less-stable powder. See here: https://en.wikipedia.org/wiki/Ammonium_nitrate , scroll to the section "Niche uses".