I think that this is the key argument fir the deaths caused. But, I was under the impression that the effectiveness of air bags compared to their hazards was coming into question in testing anyway. a seat belt saves many more lives than an airbag?

The combination is the best (apart from not crashing at all). I had heard that US airbags were bigger than European ones as they were designed to attempt to compensate for the lack of seat belt use (which was apparently common in the 90's).