Students at Midwest School had headaches, sore throats and other symptoms for more than a week that were probably due to gas leaks from a nearby well, a recent state report concludes.
When the students were moved to a new school, there was a significant drop in their symptoms, the report added.
The Wyoming Department of Health interviewed 84 students and 45 staff members about how they were feeling in the weeks before, leading up to and after the odor was detected on May 25.
Of those surveyed about how they felt in April and early May — weeks before the discovery — 57 percent reported headaches, 33 percent had a cough and 26 percent said they felt light-headed.
In 10 days leading up to and including May 25, 50 percent reported headaches, 26 percent said they had a cough and 25 percent told officials they had an irritated throat.
Headaches were the most commonly reported symptom, followed by nose irritation, cough, irritated throat, feeling light-headed and irritated eyes.
Midwest residents had previously reported similar symptoms in interviews with reporters after the leak began. The study is notable because it is the first time a state agency confirmed the accounts and provided a concrete timeline for the symptoms.
Midwest School was closed a day after testing by FDL Energy, which operates the nearby Salt Creek oilfield, revealed abnormal carbon dioxide levels and volatile organic compounds. Students were then sent to North Casper Elementary.
Further testing the week after school closed showed higher levels of CO2 and VOCs. While windows had been left open before the testing that led to the school being closed, windows had been closed for the weekend before this second round, Casper-Natrona County Health Department officials said at the time.
“It was definitely higher than we’d expect for normal carbon dioxide, and we obviously do not want to see any VOCs,” Audrey Gray, the health preparedness manager at the department, said last June.
Messages left with health department officials were not immediately returned Monday.
The report concluded that “symptoms in staff and students were likely associated with exposure to elevated CO2 and (volatile organic compounds) in the Midwest School building.” It added that after changing schools and removing exposures, “symptoms significantly decreased.” The leak was eventually pegged to a nearby well.
Volatile organic compounds are a collection of chemicals emitted as a gas from solids and liquids. The source of these VOCs can be paint and aerosol cans to oil and gas wells. Some have no known health effects, while others can be highly toxic.
The symptoms described in the report echo what Midwest students and parents told the Star-Tribune about their symptoms in June. A recent graduate said then that she’d experienced hives and feared for the health of her newborn. A mother of two Midwest students said her sons had experienced fatigue, headaches, grogginess and loss of appetite.
Test results taken two days after Midwest was evacuated found benzene at 200 times safe levels. Federal officials also said they could not guarantee the students and faculty safety in the future, given drilling in the area.
Benzene poses short- and long-term health risks, according to the health department. Breathing the chemical compound can cause dizziness, headaches and confusion. Inhalation of extreme concentrations can cause death, and long-term exposure can raise the risk of cancer.
A similar incident closed Midwest School’s kitchens in November 2014, after an odor was detected and two kitchen workers became sick. One had to be flown to Casper for treatment. Local, state and national health officials conducted what they described as an exhaustive investigation, in which they searched for methane, mold and VOCs.
“We couldn’t find anything,” Gray said in June. “It was inconclusive.”
Over 100 Midwest students have been bused to Casper so far this school year. High-schoolers have been housed on the new Pathways Innovation Center campus, and younger kids use the old Westwood Elementary building.
The Salt Creek field surrounding the school has been drilled since the late 1800s. There are 120 abandoned wells in the 640 acres around Midwest, according to state records. FDL, Salt Creek’s operator, identified and plugged the well responsible for the leak and is monitoring other wells in the area.