Inflatable vehicle occupant protection device

The present invention relates to an inflatable apparatus for helping to protect a vehicle occupant in the event of a vehicle collision. An apparatus () helps to protect an occupant of a vehicle (). The apparatus () includes an inflatable vehicle occupant protection device () that is inflatable into a position between a vehicle part () and a vehicle occupant. The apparatus () also includes an inflation fluid source () that provides inflation fluid for inflating the inflatable vehicle occupant protection device (). The inflation fluid source () contains a stored inflation fluid () consisting essentially of 65-95% helium gas and 5-35% nitrogen gas stored under pressure.