I agree with xplosv57. If she's sitting close enough for the steering wheel to hit it before the pre-tensioners have an effect then she's lucky the air bag didn't go off.

The airbag initially fills with a gas that is extremely hot but cools extremely quickly. If she hits the bag before its fully deployed she'll be getting a face full extremely hot gas which will definately cause more pain then taking a steering wheel in the chest.

Also, if she hit her chest on the wheel she should be capable of moving the chair back. i'd be more worried about her head hitting the windscreen if she's THAT close.

Anyway, good to hear that she's ok. Still a painful experience both emotionally and physically but at the end of the day she's still alive and thats all that matters.

Post some pics asap.