High radon level readings at Upper Blue may be valid | SummitDaily.com

High radon level readings at Upper Blue may be valid

FRISCO – Preliminary tests at Upper Blue Elementary School are indicating the abnormally high radon levels recorded at the school earlier this week were valid.

Data recorded in a 24-hour period between Thursday and Friday afternoon show that radon levels in the building increase at night, when the building’s ventilation system is shut down.

“We don’t know anything for sure,” said Mike Arnold, Summit School District’s facilities director. “We need to get a good 48-hour snapshot.”

School officials moved students from three of Upper Blue’s classrooms earlier this week when tests showed abnormally elevated radon levels – as high as 96 picocuries per liter of air (pCi/L) – in the southwest portion of the building.

The action level for radon is 4 pCi/L, and immediate action is required for levels exceeding 100 pCi/L. Radon is a radioactive gas that comes from the natural decay of uranium found in many soils, and can be damaging if inhaled.

Ace Radon, the consultant the district hired to lower radon levels in the school, installed fans and pipes in the school building this summer, after repeated tests indicated levels ranging from 3.5 to 41.7 pCi/L.

The first set of tests after the mitigation work was completed showed radon levels dropping, so officials were baffled when four of seven tests earlier this week recorded levels from 44.1 to 96 pCi/L. There was a chance those results were flawed, they said.

The most recent data, however, suggest the results may well have been valid.

Officials installed the first of two high-tech radon monitors in the building’s southwest wing Thursday. Unlike the commonly used charcoal canisters, which only record the highest levels, these monitors record continuous data officials can review.

Though the monitors must run for a minimum of 48 hours before the data can be considered statistically accurate, the first 24 hours of data recorded radon levels ranging from 2 to 6 pCi/L during the daytime and reaching a high of 90 pCi/L during the night, Arnold said.

If data this weekend are consistent with these preliminary reports, it likely means the building loses pressure at night, after the building’s ventilation system shuts off, creating a vacuum effect in the building, he said.

“The bottom line is, if we have to, we’re going to run the ventilation system 24 hours a day, seven days a week,” Arnold said.

Officials plan to leave the ventilation system off this weekend, to give them a better idea of what is happening within the building.

The data recorded this weekend should help determine the problem and how to proceed with mitigation efforts.

Lu Snyder can be reached at

(970) 668-3998, ext. 203, or


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