At least 40 students of a high school in Rhode Island are showing symptoms of carbon monoxide exposure, but fire officials haven't found high levels of CO.
According to WJAR, emergency crews responded to Cranston High School Thursday afternoon.
Fire officials who tested the CO said their equipment never showed high CO levels.
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WJAR reports that the issues started Tuesday night, after a student suffered headaches, nausea and exhaustion, all symptoms of higher levels of carbon monoxide.
School officials said they are looking into the possibility that the symptoms were caused by a sick faculty member.
The school will be closed on Friday.