NH – Students at Campbell High School were sent home yesterday, after elevated levels of potentially deadly carbon monoxide were detected in the school, officials said.

Indoor air was to be monitored last night, and by 6 a.m. today school officials were expected to decide whether to hold class today or cancel, officials said in a press release issued yesterday.

Fire Chief Thomas Schofield stressed that levels of carbon monoxide never exceeded the safety threshold.

He expects the school will be open this morning. If so, a Fire Department official will be on hand during the day to monitor the air. He expects yesterday’s incident involved an ongoing problem with the boiler smokestack and its proximity to an air intake unit on the school roof.

Initial problems started Tuesday night, when someone complained about feeling dizzy in the school auditorium, where balloting in the election was taking place. The Fire Department and Honeywell, the company that automates the boiler, checked and found no leaks.

At about 9 a.m. yesterday, Litchfield Fire-Rescue arrived at Campbell after receiving a number of complaints from teachers and students who were feeling ill. Specialized equipment and personnel were called in from the South East New Hampshire Hazardous Materials Team to monitor the air.

“Students were released not because of physical hazard, but for the Fire Department to run its tests,” said Steve Martin, business administrator for Litchfield schools.

Schofield said the school was to be sealed last night; tests would be run at 9 p.m. and again at 4 a.m.

In the meantime, the Fire Department overrode the computerized climate control in order to replicate daytime temperatures inside the building. More important, last night’s rain and overcast skies were expected to be similar to yesterday morning’s weather.

If weather conditions are right, the air handlers apparently suck in exhaust from the smokestack, Schofield said. He said the problem has been going on for years, and yesterday was the second time Campbell has released students early because of the problem.

School officials have attempted to address it and raised the smokestack upon the recommendations of an engineer, he said.

“The likely fix is going to be putting a mechanical device in the smokestack to force the air up higher, or redirect the air flow into the handler,” Martin said.

Schofield said the propane-fired boiler is used to heat air for the forced hot-air system.