Operations Manager Jarkko Rantanen told YLE sulphuric acid and sodium hypochlorite had leaked from the machine room.
The building was evacuated as both substances are poisonous.
According to Rantanen, the facility did not sustain any permanent damage but had to be completed aired out. The centre is to reopen on Sunday.
Rescue officials from the City of Helsinki say anyone who may have inhaled the toxic gases should seek medical attention if they experience coughing, breathing difficulties or if they suffer from chronic lung disease.