Questions about air-quality during the Cerro Grande fire? Ask Laboratory experts face to face on Thursday

Contact: James Rickman, elvis@lanl.gov, (505) 665-9203 (00-090)

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LOS ALAMOS, N.M., June 21, 2000 -- Environmental experts at the U.S. Department of Energy's Los Alamos National Laboratory have analyzed much of the data on air quality during May's Cerro Grande fire and have found that smoke from the 48,000-acre blaze did not contain unusual levels of Laboratory-derived pollutants.

Those with questions about the data or air-sampling activities can meet face to face with members of the Laboratory's Air Quality Group on Thursday as part of a public meeting and information fair sponsored by El Rio Arriba Environmental Health Association. Interested persons will be able to speak with Laboratory air quality experts at the information fair from 3 to 6 p.m. at Northern New Mexico Community College's Joseph Montoya Building. Small group forums and a large group discussion will take place at the same location from 6 to 7 p.m. and from 7 to 8:30 p.m., respectively.

"We fully appreciate that people were concerned about the possibility of Laboratory-derived pollutants in smoke released by the Cerro Grande fire," said Dennis Erickson, director of the Laboratory's Environment, Safety and Health Division. "Based on current analyses, we believe that none of our neighbors or others who were in the path of the smoke were exposed to any significant additional health risk from Laboratory contaminants as a result of the fire.

"We know that trust is established face to face, person to person, and we look forward to this opportunity to meet with anyone who might have questions or concerns about the Laboratory's environmental monitoring programs or air-quality data that was gathered during the Cerro Grande fire," he said. "We will provide candid answers to questions. The public deserves no less."

The fire burned more than 9,000 acres of Laboratory property. Shortly after the fire ignited in May, some residents of nearby communities expressed concern that contaminants from earlier Laboratory operations were being burned and spread by smoke. The Laboratory has monitored air samples for decades to assess the effects of Laboratory operations on air quality.

A monitoring system known as AIRNET is the primary system that the Laboratory relies upon for sample collection. As soon as concerns were raised, Laboratory environmental scientists stepped up their monitoring efforts, collecting AIRNET samples more frequently than they would have under normal circumstances. By shortening sampling periods from weeks to days, scientists were able to track the impact that the fire had on air quality, including the possibility of Laboratory-derived contaminants becoming airborne.

During the period between May 11 and 14, concentrations of alpha and beta radiation increased relative to concentrations measured before the fire. Alpha concentrations increased by 10 to 20 times compared to pre-fire data; beta concentrations increased by two to four times. The increases are not unusual because radioactive materials left behind from the decay of naturally occurring radon accumulate on forest vegetation over the course of years. When the fire burned the vegetation, the radon-decay products became suspended in the air. Consequently, alpha and beta radiation levels increased.

Detailed analyses of the air samples indicate that the sources of the alpha and beta particles were decay products from the isotope radon-222 and not from Laboratory-derived contaminants. Despite the observed higher-than-normal concentrations, the alpha and beta particles did not create any significant added health risk to the public.

Researchers also looked at gamma radiation. They did not see anything in the samples to indicate radionuclides from anything other than natural sources.

Laboratory scientists studied concentrations of uranium, plutonium and americium isotopes during the fire. Most americium and plutonium concentrations were comparable to concentrations observed before the fire. In the rare cases where americium and plutonium concentrations appear higher, scientists believe the analytical uncertainties also are higher because of the smaller sizes of samples collected and analyzed. In some cases, sample air volumes were about one percent of what normally is collected for isotopic analysis. Because of these small sample-size factors, Laboratory researchers do not believe the observed increases are statistically significant.

In some cases, the scientists observed uranium levels that were higher than what would have been expected. The researchers looked at the ratios of uranium isotopes in the samples to get an isotopic "fingerprint" of the samples they were seeing. For example, uranium used at the Laboratory is either enriched, which would give higher ratios of uranium 234 and uranium 235 in its fingerprint, or is depleted uranium, with a higher ratio of uranium 238 in its fingerprint. The isotopic fingerprint on uranium collected during the fire indicated that the uranium seen in increased concentrations appears to be from naturally occurring sources.

The Laboratory air-quality experts compared their data with data from other organizations such as the U.S. Environmental Protection Agency, the New Mexico Environment Department and DOE emergency response specialists. Other organizations had results similar to what Laboratory researchers found. For example, samplers operated by EPA and NMED detected increased radioactivity, but indicated that it came from naturally occurring sources. NMED samplers indicated that uranium and plutonium levels in samples they collected were consistent with pre-fire background levels for the region.

In addition, EPA monitoring stations did not find pesticides in collected air samples. The same stations found very low levels of suspended non-radioactive metals in the smoke in concentrations that would not create any adverse effects on public health. Scientists do not believe these metals are Laboratory derived, but are from a resuspension of naturally occurring soils and from burned vegetation.

In addition, the Laboratory looked at data obtained by NEWNET, a community radiation monitoring network used for educational purposes. NEWNET stations located at local and regional schools and at other locations nearby did not detect any significant increases in radioactivity in ambient air due to the fire.

More news releases from the Environment, Safety and Health (ESH) Division