An airbag can kill someone (child or adult) if the person isn't using a seat-belt. The bag is designed to inflate and deflate very quickly, providing just enough cushion for the person flying forward before the seat-belt kicks in.

They should start showing the UK seat-belt adverts here. They're really horrific and get the message across so well. I've noticed some of the UK radio adverts on QBS, so maybe the TV one's will come soon (hopefully with Arabic translation!).