Concerns raised about possible age-related failures.

If you drive a car that was built in the last 20 years, chances are it has at least one airbag. But can you be sure the airbags in older cars will actually work in the event of a crash?

According to The Detroit Bureau (TDB), concerns are being raised about the longevity of airbag systems, especially those with chemical inflators. That particular type of airbag uses volatile ammonium nitrate which produces hot gases when the inflator is triggered, propelling the airbag out.

But ammonium nitrate breaks down over time. The rate of decay is fastest in hot, damp climates, but in dry states it will eventually start to decompose, as well. The chemicals could even break down if the car is used regularly on rough roads, being literally shaken apart.

Research by the National Highway Transport Safety Administration has shown that airbags with ammonium nitrate inflators produced by beleaguered Japanese supplier Takata for 2001 to 2003 model year cars could have a failure rate as high as 50 per cent.

Other types of inflators are used, such as compressed gas and explosive charges, but these are not without their own problems. Gas canisters can lose pressure over time, and explosives can also suffer chemical breakdown.

Some manufacturers are starting to add measures intended to extend the life of an airbag inflator, or detect any problems. But, with the average age of cars on U.S. roads now at 11 years, the problem of how to detect problems in older airbags persists. It’s much like Schroedinger’s Cat: either the airbag will go off or it won’t, and the only way to know for sure is to crash the car and see if it goes off. Schroedinger’s Airbag, if you will.

Recent recalls of cars fitted with Takata airbags that could overinflate, sending shrapnel into the car, plus an investigation into those made by American firm ARC Automotive, sparked by the death of a Canadian motorist, have brought the safety of airbag systems into focus.

TDB quotes an interview given by NHTSA Administrator Mark Roseking, in which he said: “Cars are lasting on the road a lot longer than ever before. Is [airbag] aging now an issue? That’s part of the investigation going on.”

Scott Upham, a consultant at Valient Market Research, which works with airbag suppliers, commented: “You’re using a chemical [inflator] that probably should be changed at least at the seven-year mark. The automakers really don’t want to admit that, [but] I think that’s going to be the result of this Takata debacle.”

Possible solutions to the problem, according to TDB, could be reliable tests or sensors to detect any problems, or the introduction of expiration dates. But that wouldn't help drivers facing the Schroedinger’s Airbag scenario.

Even so, it’s worth remembering that airbags are estimated to save thousands of lives every year in the U.S. alone. And that the idea is to not crash in the first place.

Source: The Detroit Bureau