As more than 2,500 students returned to classes at Carson High School on Friday, the nurse's office remained closed following a mercury spill there that took nearly two days to clean up.
Mike Mitchell, director of operations for the school district, said two hallways and four classrooms were cleansed of the toxic pollutant by an environmental cleanup company out of Reno. The carpeting in the nurses office, however, will have to be removed, prompting officials to relocate the nurse to another area.
According to the Environmental Protection Agency, mercury affects the nervous system and can lead to death from overexposure.
It's believed at some point Wednesday someone who visited the nurse's office intentionally removed a screw cap from a mercury-filled capsule on a blood pressure machine and forced most of the silver element out onto a desktop.
The discovery came about an hour before students were set to leave school early for teacher meetings.
Eighteen students and eight staff members who visited the nurse's office Wednesday came up positive in an air test for mercury and underwent decontamination. Subsequent tests of the environment revealed the mercury, which vaporizes at room temperature, was carried for a short time through the buildings air vents, contaminating nearby rooms and hallways.
Mitchell said environmental cleanup crews spent Wednesday evening and all day Thursday cleaning, testing, cleaning and retesting the areas in which mercury was detected. At 10:30 p.m. Thursday, the final reading of the night revealed there was no mercury detectable outside of the carpeting in the nurse's office.
Mitchell said the cost of cleanup has yet to be tallied.
Friday, three remaining outdated blood pressure machines were removed from other schools in the district.
Carson City Sheriff's Deputy Mark Jongsma said the determination of an intentional spill was reached when an investigator from the EPA noted the machine is self-contained inside a box, yet there was no mercury spilled inside the box, but there was mercury on the box's exterior. He said a quarter of the mercury used to gauge pressure was all that was left in the vial and a little more than a teaspoon was found on papers on a desktop. Additionally, Jongsma said, the cap that keeps the element contained was unscrewed and missing from its threads.
Sheriff's Sgt. Bob White said investigators will speak with all 26 people who had access to the nurse's office on Wednesday.
"I think we'll be done investigating by the end of next week," he said.
Mitchell said students will not have to make up the missed day at the end of the year.
n Contact reporter F.T. Norton at ftnorton@nevadaappeal.com or 881-1213.