County’S Radon Rate Highest In State

Spokane County has the highest levels of cancer-causing radon gas in Washington and is the only county assigned to the “very high” exposure category in a new report by the state Health Department.

Another revelation in the report is that northeastern Washington residents receive more than four times as much overall radiation as previously believed - and 4.7 times the national average.

The average annual radiation dose from all sources in Spokane, Stevens, Pend Oreille, Lincoln, Ferry, Grant and Douglas counties is now estimated at 1,682 millirems per year. That compares with a previous estimate of 400 and a national average of 360.

Federal regulations say people who work with radioactive materials may safely be exposed to 5,000 millirems per year.

Health officials estimate the average person in Spokane County absorbs more than 1,900 millirems of radiation each year.

“This is very high,” said T.R. Strong, director of the Health Department’s Radiation Protection Division. “Statistically, the potential for contracting lung cancer is there at these rates.”

But he said people shouldn’t panic because most of the radiation comes from radon gas, which can be controlled relatively easily. Corrective measures such as ventilation fans and pipes to capture and reroute the gas may cost homeowners $500 to $2,500.

“All that exposure is simply not necessary,” Strong said. “It is so easily controlled.”

All occupied buildings in this region should be checked for radon, according to Geoffrey Hughes, the Health Department radiation policy analyst who wrote the report.

“I would definitely test my home,” Hughes said.

Strong said the best test is a six month sample covering the winter, when closed doors and windows trap the gas. Although radiation comes from the sun, X-rays and numerous other sources, 88.6 percent of radiation people absorb in northeastern Washington comes from radon gas. Because it is inhaled, radon damage is focused on the lungs.

The Health Department report concludes there no longer is any doubt that radon can cause lung cancer even without complicating factors such as smoking or working in a dusty environment.

The report says 60 percent of the houses in Spokane County have 4 or more picocuries of radon gas per liter of air. That corresponds closely with preliminary findings in a separate Spokane County Health District study. The district reported Thursday that 63 percent of 2,826 houses had radon levels above 4 picocuries, and the average was 10.6 picocuries.

But state report is based on a national testing program in which the U.S. Environmental Protection Agency checked 451 single-family houses in Spokane County in 1991 and 1992. The EPA study found that 29 percent of the Spokane County houses had levels of 10 picocuries or more, and the highest reading was a whopping 152.2. Half of the houses had less than 10.2 picocuries, and half had more.

Four picocuries is the level at which the U.S. Environmental Protection Agency believes corrective action should be taken. The Washington state Health Department recommends action at that level and believes action is necessary at 10 picocuries per liter or more.

The decision to classify Spokane County’s radon risk as “very high” also was based on a Bonneville Power Administration test of 678 homes in Spokane County. Those tests were said to show results similar to those in the EPA tests, although the BPA took longer-duration samples that tended to show lower numbers.

The BPA found that 36 percent of the houses tested had levels of 4 picocuries or more. Half of the houses in those tests had levels below 5.2, and half had higher levels.

In addition to home testing, radon risk categories in the Health Department report are based on aerial radiation measurements and analysis of geological maps used to locate uranium deposits.

Spokane County is described as a transition zone between the highradon Okanogan Highlands and the relatively low-radon Columbia Basin. Most of the southern part of the county has low radon risk. The Spokane Valley lies between two highrisk zones and has a “variable” radon threat.

The high-risk areas are said to be in the northeastern part of the county and in a narrow band south of the Spokane River, from the central part of the county to the Idaho border.

Graphic: How Radon Enters A House

Jeanette White contributed to this report