If you haven't tested your home for radon gas...you should buy a test kit at a hardware store.   They cost between $10-$30.  Radon is a naturally occurring radioactive gas that can cause lung cancer.  Brett Sherry, with the Oregon Health Authority, says it's important for all homeowners to run the test, because radon levels vary from house to house.  New test results show the Portland area can have levels double the national average.  That's because floods that occurred thousands of years ago pushed soil with granite into the area and that soil can contain higher levels of radon gas.