Valhalla? Oh, it's full of souls. Not just human ones, mind you, but the souls of ships, and war animals, and other such beings.
Madness string 77738
The main problem with dust storms isn't the dust itself (although breathing that in isn't great). It's the stuff that comes with it. There's a fungus that gets kicked up, and breathing it in lets it take root in your lungs and causes all sorts of problems.