Aside from that, Spokane does have higher levels of radiation than elsewhere, statically.

As noted in the following article on the topic of Radon.

[link to www.spokesman.com (secure)]
Local phenomenon
The Spokane area has an interesting geology that gives it a very high prevalence of radon gas, according to information from the Washington State Department of Natural Resources.

“In your corner of the state, there’s more uranium and radium in the ground than in other places,” Brennan said. “There were, after all, three uranium mines there.” [link to www.spokesman.com (secure)]