Emergency responders gave the OK to end an evacuation of West Harrison High about 10 a.m. today.
The school, located on County Farm Road, evacuated about 1,000 students, who spent the morning on the football field while first responders cleared the vapor from a Freon leak from an air conditioning unit on the second floor.
The evebt drew a major response as a Hazardous Materials incident. It was first reported as an ammonia leak with a maintenance worker down or missing.
The worker was not missing and authorities determined the leak came from work that contractors were performing on the air conditioning compressor.
County Fire Marshal George Mixon said firefighters responded to the call at 8:58 a.m. today. The building was evacuated.
The Sun Herald updates this story in Saturday's edition.