Elevated levels of radon, a naturally occurring, radioactive gas, have been found in three Carson Valley schools and one Lake Tahoe school.
According to results of a district-wide test, the staff lounge and room 24 at Carson Valley Middle School, room three at Gardnerville Elementary, room G-9 at Pau-Wa-Lu Middle School, and more than half a dozen rooms at Whittell High School all contain levels of radon above the EPA's guideline of 4.0 picocuries per liter.
In the Valley, levels marginally exceed the guideline, ranging from 4.1 picocuries per liter at Carson Valley Middle School to 5 picocuries per liter at Pau-Wa-Lu.
However, the results paint a different picture at Whittell High School. Out of 56 locations tested on the site, seven yielded elevated levels, ranging from 4.2 picocuries per liter to 13 picocuries per liter.
Colorado Vintage Companies performed the tests March 16-20 while school was in session.
On Tuesday, District Chief Financial Officer Holly Luna told school board members that continuous radon monitors will be installed in the schools to further assess the levels.
"They'll pull in information directly," differentiating between daytime and nighttime levels," she said. "At night, when the HVACs are not flowing, there can be higher levels of radon."
Luna was hopeful that adjusting airflow in the rooms would lower the levels.
"If HVAC readjustments don't mitigate levels, we'll follow up with remediation similar to that used at Zephyr Cove," she said.
Last year, elevated radon levels at Zephyr Cove Elementary set off debate when parents, unhappy with the district's decision to close Kingsbury Middle School, argued that Zephyr Cove be closed instead.
However, the district was able to work with the EPA and install a ventilation system that prevented the gas from entering the buildings, lowering levels in time for the new school year.
Radon is produced by decaying uranium in granitic soils. The colorless, odorless gas usually dissipates into the air, but can enter buildings through crawl spaces.
Once trapped, the gas' radioactive decay can pose serious health risks. According to the Nevada Radon Education Program, long-term exposure to the gas is the leading cause of lung cancer among nonsmokers.
But radon is nothing new for the Douglas County School District. The district was one of the first in the state to test for the gas in 1989 when levels were reaching upward of 25 picocuries per liter.
Luna said results of the recent tests will be posted on the district Web site, dcsd.k12.nv.us.
She said the district will continue to update the public on mitigation efforts.
"We're taking a progressive approach," she said. "Here are the results, here's what we're doing, and we're going to keep updating people."
