One student and a staff member were taken to the hospital to be evaluated after an issue with a science experiment at Berlin High School on Wednesday morning.
The Berlin Fire Department said the experiment caused a nitrogen dioxide leak around 10 a.m.
The experiment was being conducted on the second floor of the school and the school was evacuated immediately.
The fire department said nitric acid and copper pennies were used in the experiment and a tube broke, causing the gas to enter the atmosphere.
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In high concentrations, nitrogen dioxide can be a respiratory irritant and cause dizziness, according to the fire department.
One student and one staff member complained of dizziness and eye and throat irritation and they were taken to area hospitals for further evaluation.
Fourteen students were evaluated at school and released.
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The fire department said families of the affected students were notified.
The fire department ventilated the area to clear any of the remaining gas from the school and the experiment was taken outside.
The air quality was metered and deemed safe to allow students and staff to return to the school.
