Duluth, MN (NNCNOW.com) --- The investigation into carbon monoxide poisoning that sent dozens to the hospital at Fryberger Arena in Duluth has closed without any conclusive answers.
In November Fryberger arena was evacuated, and several people were hospitalized, after high levels of carbon monoxide were found.
The Minnesota Department of Health tested the arena twice and found acceptable air quality limits.
They were unable to clearly identify what caused the people to get sick.
Inspectors did find a failure to meet acceptable methods for maintaining safe air quality and issued a correction order to develop, communicate and execute a plan to meet state standards.
Since the incident, Fryberger has made several changes including relocating the boiler and hot water heaters to ensure better ventilation.
They also had a technician examine the ice re-surfacer and are working to install a Carbon Monoxide monitoring system even though it's not currently required by the state health department.
"We'll continue to inspect this arena and continue to check their air quality records,” Dan Tranter, Indoor Air Unit Supervisor said. “If we identify additional violations, we may proceed to additional enforcement action."
Fryberger Arena is now required to submit carbon monoxide levels quarterly, to the Minnesota Department of Health.