By Laura Zuckerman
The Idaho Falls Post Register
SALMON, Idaho — Recent air samples near North Fork showed radiation was higher than the national background level but did not threaten human health, officials said.
Sampling was done after the Mustang Complex fire consumed former mine sites with measurable uranium and thorium.
The massive wildfire in the Salmon-Challis National Forest north of Salmon swept through a defunct uranium mine Sept. 11; just weeks after flames claimed two abandoned gold mines contaminated by radioactive elements.
The former uranium mine and milling operation, subject to an EPA cleanup in 2008, and the shuttered gold mines, sit along a 21-mile stretch west of North Fork.
Several North Fork residents expressed concern last month about whether radioactive elements — many naturally occurring in rock and soil — fixed in place by plants and trees would pose a health risk when made airborne and released in the smoke that cloaked the area for weeks.
Air samples collected by the Idaho Department of Environmental Quality in North Fork on Sept. 21 and Sept. 22 revealed heightened levels of radiation but none that were harmful to humans, DEQ health physicist Paul Ritter said.
“The concentrations (of alpha and beta particles) were elevated as expected but they lie in the same range or at the high end of the range of what we see in the eastern Snake River Plain during stagnant air conditions in the winter,” Ritter said.
During inversions, radiation and other air pollutants build up in the atmosphere instead of dispersing and diluting.
Based on testing, North Fork area residents would have been exposed to 0.5 millirems of radiation in a 30-day period, Ritter said.
That compares to the estimated 310 millirems to which Americans are exposed every year from natural sources, as well as a 1-millirem dose delivered by a coast-to-coast airline flight, according to the U.S. Nuclear Regulatory Commission.
Findings from further EPA testing of air samples collected at North Fork are expected in December.
Those results likely will identify the sources and types of emissions.
Firefighters were ordered to stay clear of any abandoned mine sites amid the Mustang Complex blaze, which had consumed about 340,000 acres as of Monday.
Wildfire smoke caused the air in Lemhi County to be rated unhealthy for weeks, triggering numerous health alerts.
Landscape smoke, blamed for more than 300,000 deaths a year worldwide, can cause small particles to lodge deep in the lungs and bring on or worsen respiratory or cardiovascular ailments.
Cindy Hallen, who lives near the former uranium mine, was not reassured by air testing that took place many days after the mining sites had burned.
“We’re left with gaps in knowledge,” she said.
Copyright 2012 The Post Register
All Rights Reserved