The concrete used in Insulated Concrete Form walls is between 6" and 12". This provides for an extremely massive structure that protects the home occupants from injury. Insulated Concrete Form (ICF) have proven track record of protecting the occupants from the damage of hurricanes, tornados and fires.
The polystyrene used in making Insulated Concrete Forms (ICF) is treated to prevent combustion. Also, flame propagation from outside sources is much less than traditional wood framed homes. The flame cannot travel through concrete, since concrete cannot burn. Only the heat of a flame is carried through the wall. This can take considerably longer than the time that a wood framed wall will transmit heat. It can take from 2-4 hours for a concrete wall formed using ICFs to transmit enough heat through it to start a fire on the other side. This compares to a wood framed wall taking one hour or less. And of course, wood is combustible so flames can propagate from one side of a wall to the other.
The Southwest Research Institute reviewed the emissions given off by polystyrene ICFs exposed to extreme heat and fire. They found them to be no more toxic than those of wood.
A home built using Insulated Concrete Forms also resists wind damage. The Wind Engineering Research Center studied the effects of an impact from a 2 x 4 wood stud on walls made of wood framing or concrete. The 2 x 4 stud used traveled up to 100 mph. This is the speed that 99% of the tornados can propel debris. As you would expect, the Center found that walls made of wood framing were "completely perforated." The walls of concrete made using Insulated Concrete Forms only had the polystyrene and exterior vinyl siding penetrated. The 2 x 4 stud could NOT penetrate the concrete. Thus, the occupants of the ICF home are far safer from flying debris.