H. Glenn Adams, on-scene coordinator for the EPA's Emergency Response and Removal Branch, was at the school overseeing the cleanup efforts.
The mercury contamination occurred when a student brought mercury to school last week.
Adams said the initial cleanup is almost complete. He noted that the primary areas of concern have been a janitor's closet, three classrooms, the library and the gymnasium. The janitor's closet was the area of greatest concern based on Lumex readings. The Lumex is an expensive air-monitoring tool specifically designed to monitor mercury vapors.
The areas of concern were closed off to students as a precautionary measure. Air samples were taken throughout the entire school, according to a press release.
Adams said the design of the school was helpful in the cleanup process because it allowed certain areas of the facility to be closed off and not interfere with school.
"I have a high level of confidence that this has mitigated the problem," he said.
Mercury is a naturally occurring metal which has several forms. The metallic mercury found at the school is a shiny, silver-white, odorless substance that is liquid at room temperature. If heated, it is a colorless, odorless gas.
Mercury can be found in thermometers, barometers, thermostats, dental offices, blood-pressure devices, fluorescent light bulbs and even in some tennis shoes that light up.
According to Harlan County Schools Safe Schools Coordinator Jim Middleton, the student who brought the mercury to school had found it on some property his family owned in an old structure on the property.
Adams said testing would continue Tuesday, and officials may remain on site for an additional day or two as a safety precaution.
According to the release, although the EPA action levels for mercury were exceeded in some areas, health concerns are very minimal due to the location of the mercury beads themselves.
The acceptable levels are set to avoid health risks to sensitive populations, such as small children.
Middleton said school and district staff reacted immediately to news of the release last week after being alerted to it by a concerned parent. Various agencies were contacted for guidance on the matter, including the health department, poison control center and hazardous materials.
Adams explained that his agency received an anonymous call on Saturday, alerting them to the release. He was dispatched to Green Hills to test the air levels and to oversee any cleanup.
Contractors from Atlanta and Nicholasville are on site conducting the cleanup.
Adams said this is the third mercury contamination reported in Kentucky schools since September. All have occurred as a result of a child bringing mercury to school or an incident in a chemistry lab.
"We want to help relieve parents' concerns," said Adams. "We will sample clothes and shoes if they wish. If you want clothing items samples, please put them in a trash bag, seal them and bring [them] to school."
The estimated cost of the cleanup is between $20,000 and $40,000 and is being funded by the EPA.