MOUNT VERNON — Ten employees and approximately 30 patrons were evacuated from the Public Library of Mount Vernon and Knox County’s main branch at 201 N. Mulberry St. on Friday afternoon, when employees found what they believed to be smoke filling three rooms of the building.

“It had a real chemical smell,” said librarian Linda Qualls, coordinator of the extensions department.

Qualls’ office in the extension department was one of three areas filled with the smoke and vapor.

“I was down there for about 20 minutes and was heading out of the department,” Qualls said, standing outside with co-workers while Mount Vernon firefighters investigated the situation.

“Then I came back in and smelled the smoke and could see it rolling under the door,” she said. “I had no idea what was going on.”

Office manager Lisa Blaisdell was the first to discover the smoke-like clouds in the boiler room and garage. She said she immediately sought to inform network administrator Jason Bostic, who is a Fredericktown firefighter.

“‘It’s the boiler room, Jason,’ I told him, and he took off running,” Blaisdell said. “We’ve had some problems with our chiller [air conditioning system] and I saw mist that smelled electrical.”

“It smelled lightly of smoke, possibly electrical,” Bostic said of the vapor he found when he arrived in the area of the building affected.

Blaisdell immediately ordered the evacuation of the entire building. The Mount Vernon Fire Department was called, and arrived around 1:40 p.m. with two engines companies and a medic crew.

Incident Commander Capt. Barry Bowden said crews were out on inspections at the time and responded from different areas of the fire district.

“We did a full response,” Bowden said.

The fire trucks staged on different sides of the building as firefighters went through the rooms filled with vapor.

“It was actually more like a mist,” Bowden said of the clouds of vapor. “It didn’t set off their own monitoring system, which tells us it wasn’t smoke.

“It seemed like it was an air handling unit and electrical,” he said. “It is a boiler room issue.”

Although unable to definitively identify the source of the vapor and chemical smell, firefighters were satisfied the situation seemed to resolve on its own.

“We aren’t certain we pinpointed the problem, but it has dissipated,” Bowden said as firefighters wrapped up their work and prepared to return to the station.

Bowden said the library maintenance staff would be watching for any further problems.

Bostic, a member of the library’s safety team, said the preplanning the staff did in preparation for such an emergency made the evacuation a smooth process.

“We meet as a team throughout the year to go over the OSHA guidelines, to retrain staff, we discuss use of fire extinguishers, building evacuation procedures, and we do our own in-house inspections to look for safety hazards and fire violations and correct them,” Bostic said.

Library director John Chidester arrived as fire crews were wrapping up their investigation. He praised the quick work of library employees who swiftly evacuated the building, as well as the safety team’s work keeping employees prepared for an emergency.

“We have evacuation plans and we have a great emergency guy here who keeps us on our toes,” Chidester said, indicating Bostic. “A public building this size and with all of the mechanical equipment we have here, we try to be as prepared as we can.”

Chidester said the implementation Friday of the plan prepared by the safety team was “just about textbook.”