During WW2 and before Cold War. During the Cold War, people reinforced their basements.
I'm sorry but this is a prime example of you passing off stuff as knowledge.
The Civil Defense made fallout shelters in every major public area to avoid a near-miss atomic blast. Personal shelters came during the 1950s and 1960s at the height of the Cold War.
WWII would have been Air-Raid shelters and Air-Raid drills, mostly in England, Germany, and Japan.