This isn't a list of the biggest cause of deaths in Idaho - it is a list of the most common uncommon cause of death by diseases in Idaho vs the rest of the United States.

The Center for Disease Control has a list that covers 2001-2010 and found what most of us already know - the air in Idaho can be very stinky. Apparently though, it also causes quite a few deaths!

Idaho's most 'Distinctive Cause Of Death' is a pretty broad list

Water, air and space, and other unspecified transport accidents and their sequelae

I take that as our water, air, and roads are not safe. Also sequelae is not a made up word, it references a condition caused by a previous disease.