Comment: Nuclear fallout from a detonation somewhere in the world could be a world problem. The CDC has a lot of information -- these links and charts give one a start.
The Community Reception Centers would be set up in safe areas 24 to 48 hours after the radiation event.
Some history from when the Navy began to test and experiment and learn about radiation:
https://www.usni.org/magazines/proceedings/1964/may/defense-against-nuclear-attack-sea
USN plaque inside a destroyer mess area read roughly as follows:
In the event of a nuclear attack
Do not look at the blast
Stay inside the ship
If outside, come inside and get decontaminated
_________________________________________________________________________
CDC RADIATION EMERGENCIES
https://www.cdc.gov/radiation-emergencies/index.html
What to Do: Get Inside
What to Do: Stay Inside
What to Do: Stay Tuned
__________________________________________________________________________
Quote from the Navy link above:
Personnel defense against the effects of surface and air bursts is time phased. At the first flash, exposed personnel should close their eyes, cover their faces with their hands, and drop to the deck behind the best shelter available. After the flash or heat sensation is over, they should then grasp some part of the ship’s structure before the air blast hits.
The defense against ionizing radiation is to seek cover. With adequate warning, many personnel normally stationed topside can go below to “deep shelter” below the waterline, otherwise, at detonation, the shelter available to anyone topside is chancy, depending on the amount of shielding material between the man and the source of radiation. The fallout hazard may persist up to 24 hours, depending on weapon yield and burst conditions.
Another fascinating Navy quote from same article:
Because earlier tests had shown that water can decontaminate surfaces that had been subjected to radioactive fallout, U. S. Navy ships participating in the March 1954 Pacific test had been equipped with a “washdown system” capable of covering topside areas with a spray of clean sea water. Ten ships 25 miles from the explosion were unexpectedly subjected to fallout. By energizing the washdown system and sending most personnel below decks, the ships survived the danger of fallout, and no one on board received excessive radiation.