As long as your husband doesn't have to deal with intense heat (and let's hope as a local truck driver, he doesn't), acrylic should be fine. It's not as warm as wool, but it's still pretty warm.
Knitpicks.com has some nice superwash wool that's really soft. I'm not sure they have it in bulky, but I know they have worsted, and it's really good for hats.
And mojo, the acrylic yarn might survive a nuclear holocaust, but it would probably all be melted into blobs, doncha think?