Father Judge High School will reopen Thursday after the Archdiocese of Philadelphia confirmed no toxic substances were present in the building.
The school, which was closed Monday for an off-site teachers' in-service day, was shut down Tuesday and Wednesday after about 150 people reported to emergency rooms complaining of eye and skin irritation after attending a cheerleading event Sunday in the Northeast school's gymnasium.
The city Department of Public Health cleared the school to reopen Wednesday, but the archdiocese decided to wait for test results from the contractor it hired to evaluate the issue.
Those results came back all clear, though neither the city nor the archdiocese was able to determine the cause of the irritation.
The school was originally set to be closed Thursday in honor of the Feast of the Immaculate Conception, a holy day, but classes will be held at archdiocesan high schools to make up days lost as part of the teacher strike at the beginning of the academic year.