Several buildings at Aamjiwnaang have reopened after incorrect benzene readings were detected at an air monitoring station on the First Nation Wednesday morning.
Band council shared the update in a letter to residents Wednesday afternoon.
"The Ministry of the Environment, Conservation and Parks [MECP] informed Aamjiwnaang that a calibration scan occurred at the Sportscentre monitor at 4 a.m. this morning," the notice read. "The calibration ensures the monitor is reading the ambient air concentrations at the proper range. The span gas did not fully purge from the chamber before the monitor came back online and therefore an incorrect high value was recorded in error."
The First Nation added that winds were primarily from the south at the time.
"Away from the INEOS facility and the INEOS fence line monitors did not record any levels of benzene at the property line," Aamjiwnaang added.
Buildings in the administration complex were closed early Wednesday, and staff were told to work from home, after benzene levels over 100 micrograms per cubic metre were reported on the Clean Air Sarnia and Area website.
Band council reopened the band office, blue building, environment, child and family services, education, CIDL and public works buildings with limited services following further investigation Wednesday afternoon.
All band administration buildings and operations will resume as normal on Thursday, August 15.
In an email to Sarnia News Today on Wednesday, INEOS Styrolution said monitors at its Sarnia site did not pick up any spikes and the below information was communicated and reviewed in collaboration with MECP:
All eGC’s recorded low Bz readings around this time (<1 ppb)
All eGC’s showed wind direction coming from the south (155-195 degrees from INEOS Styrolution i.e. wind from Aamjiwnaang First Nation to INEOS Styrolution)
INEOS said it confirmed with MECP Wednesday morning the reading was likely due to a monitor error outside of the control of INEOS Styrolution.
The company said INEOS is not the only source of benzene in the area.
-with files from Stephanie Chaves