Takata Failures Seen Caused by Design, Environment

Researchers hired by a coalition of automakers found that moisture—seeping from the environment into the inflator and not dried by a chemical—is the reason Takata Corp. air bags rupture and spray shards of metal and plastic at motorists.

The findings were based on tests conducted by Orbital ATK, a suburban Washington, D.C., company that makes rocket-propulsion systems. The Feb. 23 findings will be used by government regulators to determine how many vehicles equipped with Takata air bags need to be recalled, and by automakers scrambling to design and build replacement parts.

Even though the findings may help accelerate repairs, the ...