Determining optimal fallout shelter times following a nuclear detonation

In the event of a single, low-yield nuclear detonation in a major urban area, rapidly providing adequate shelter to affected populations could save 10 000–100 000 individuals from a fatal exposure to fallout radiation. However, poorly sheltered individuals may remain at risk. Current guidance and prior studies are not consistent as to the timing and conditions under which poorly sheltered individuals should leave their shelters to evacuate or obtain better shelter. This study proposes methods to determine the optimal shelter time based on information potentially available following a nuclear detonation. For the case in which individuals move to an adequate shelter that can be reached within 15 min, individuals should stay in a poor-quality shelter for at most 30 min after the detonation. If adequate shelter is available nearby (within 5 min), then poorly sheltered individuals should immediately proceed to the better shelter.