Buildings around the Ada (Lockridge) Rogers and Aamjiwnaang sportscentre air monitoring system were closed Sunday.
The First Nation said through its notification system at 9:30 a.m. high benzene levels were detected in the area early in the morning.
Aamjiwnaang's ball diamond, playground, band office, blue building, environment building, child and family services building, education administration building, CIDL, public works and the church will be closed for the remainder.
These areas will also be closed on Monday, June 9.
Benzene levels reached 15.6 at around 7 a.m.