Expert advice published in the 2010 document "Planning Guidance for Response to a Nuclear Detonation" is to shelter in place, in an area away from building fires, for at least 1 to 2 hours following a nuclear detonation and fallout arriving, and the greatest benefit, assuming personnel are in a building with a high protection factor, is sheltering for no less than 12 to 24 hours before evacuation. Therefore, sheltering for the first few hours can save lives. Indeed, death and injury from local fallout is regarded by experts as the most preventable of all the effects of a nuclear detonation, being simply dependent on if personnel know how to identify an adequate shelter when they see one and enter one quickly, with the number of potential people saved being cited as in the hundreds of thousands. Or even higher if the remaining occupants of the city are made aware of the contaminated areas, by emergency systems, within hours of the event's aftermath. In 2009 to 2013 a further iteration on sheltering-in-place was made to determine the optimal improvised fallout-shelter-residence-times following a nuclear detonation, with computer analysis, and including a summary of prior studies and guidance. It was found that individuals should quickly get into the best intact building at least under 5 minutes distant in travel time following the detonation and they should stay there for at least 30 minutes before venturing out to find a shelter with a higher protection factor but that is a greater travel time away than 10 minutes. However, although this would be effective in cases where the initial building protection factor is less than about 10, it requires a high degree of individual situational awareness that may be optimistic to assume following the shock of a nuclear detonation. If a building with a PF of 20 or more is nearby, such as the fallout shelters depicted in the film, in the vast majority of fallout circumstances, it would not be advisable to leave it until 3+ hours have elapsed following the initial arrival of the local fallout.