Probably irradiated fallout particles being blown in from the Glowing Sea.

Here are my observations on how radstorms are currently implemented:

• Going to an interior cell does not work because the storm just waits for you to come back out.


• Wearing a vaultsuit helps quite a bit


• Fast travel can get rid of the storm (but in my experience I have to go a long ways away).


• Sleeping through it seems to make it go away without taking rad damage.


• Medics can cure the rads, if you want to spend caps that way


• Mutant hound steak probably tastes bitter, but also works for after


• Radaway, of course, cleans you up (and seems quite plentiful despite 200 years - mass production is a wonderful thing...)


• Those hazmat suits are great for radstorms, but not for fighting (unless it's children of the atom you are fighting).


• They are pretty


• I do not think I want to experience on in real life. But maybe that is just me being strange.


• glowing blood packs or even baked bloatfly can help.


• pc perks can help deal with rads, and perhaps we can imagine npcs have access to something anologous.


• There are a some other ways of dealing with rads, but those are sort of spoilerish and/or mostly pc exclusive because of rarity.

Pretty much every SciFi movie that has a meme of rad-storms shows people scrambling for cover when the storm is moving in. Makes sense in a Kansas twister sort of way. Then in Skyrim, there is a mod titled, "Run For Your Lives" http://www.nexusmods.com/skyrim/mods/23906/? which causes NPCs to run for cover when a dragon attack starts. Rad storm/dragon attack, pretty much the same thing: it has become unhealthy to be outdoors. I figure if a modder can develop such a NPC response to an event, Bethesda should certainly be able to do as much.