Fire radiation not from fallout, study finds

A study by experts at the University of Nevada, Las Vegas, says radiation put into the air of southern Utah during wildfires resulted from naturally occurring material.

But J Truman, president of the fallout survivors group Downwinders United, criticized the monitoring methods and the fact that it took two weeks to produce a report on the issue.

From July 5-July 10, the federal government's radiation monitors of the Community Environmental Monitoring Program recorded spikes in gamma radiation at Milford, with readings at times far above normal.

Usually, this form of radiation is measured at 20 or 21 microrems per hour. But during that period the readings were much higher, in three instances going off the chart. Officials estimated that the highest radiation during the period was 136.8 microrems per hour, still not enough to cause health effects.

The monitor's chart also showed the minimum to be minus 7.3 microrems per hour, an impossible reading that may reflect the wild swings of an automatic recording pen jogging up and down on graph paper.

No other station in the 29-monitor network, operated by the National Nuclear Security Administration, showed a jump in radiation. The increase in radiation in the air had been blamed on the nearby Milford Flat fire, the largest since Utah was settled, but that conflagration started on July 6, the day after some of the most dramatic spikes.

However, other fires may have been burning in the region at the time.

Downwinder groups feared the material causing the spikes could have been fallout lofted from the ground or plants by fire. They cited the heavy radiation that fell on the region during open-air nuclear testing at the nearby Nevada Test in the 1950s and early '60s.

But the UNLV report released on July 20 seemed to rule out fallout and an official from the National Nuclear Security Administration agrees with the report.

The study, posted on the Internet at www.nv.doe.gov, was carried out by UNLV health physics department, Radiation Services Laboratory. After analyzing air samples collected in Milford, the scientists concluded that fallout was not involved.

"Initial screening by gamma spectroscopy did not indicate the presence of unusual levels of man-made radionuclides in these filters," the report said. Cesium-137, which is a long-lived component of fallout, "was not detectable in any of the filter samples analyzed."

However, several naturally occurring radioactive substances were identified in the samples: Beryllium-7, produced in the upper atmosphere; Lead-212 and Lead-214 derived from the decay of natural uranium and thorium, and Potassium-40, "which is present in atmospheric dust particles and virtually all other types of geological materials."