Midwest School in Midwest, Wyo., will remain closed until the 2017-18 school year as engineers and consultants work to mitigate air quality problems caused by a leak from a nearby oil well.

The Casper Star-Tribune reports that more than 150 students from the Midwest School, a K-12 campus in the Natrona County district, will continue to be bused 40 miles south to campuses in Casper while environmental consultants design and build a mitigation system that will pump air away from the school and monitor air quality.

The Midwest School was evacuated in May and subsequently closed after students and staff reported headaches, sore throats and other health problems. A state report said the symptoms were likely caused by the oil well leak. Testing found high levels of carbon dioxide and volatile organic compounds in the air.

The school is surrounded by the Salt Creek oil field, which is operated by FDL Energy. After the leak was detected, FDL plugged the well in question. Testing taken two days after the school campus was evacuated measured benzene at 200 times safe levels.

Benzene poses short- and long-term health risks. Breathing it in can cause dizziness, headaches and confusion. Inhaling extreme concentrations can cause death, and long-term exposure can increase the risk of cancer.

Federal officials have said they can’t guarantee the safety of students and faculty in the future. Officials are hoping the mitigation measures being put in place will prevent further leaks. FDL is footing the bill for the mitigation system.