Singapore Civil Defence Force(SCDF) had earlier announced on its Facebook page that it was called for assistance to a gas leak incident at 9.20 am today (4 September).
It deployed 3 fire engines, 4 Hazardous Materials (HazMat) appliances, 3 ambulances, and 2 support vehicles.
SCDF had traced the leak to a one-tonne cylinder of chlorine housed within an indoor storage facility.
Within 20 minutes, the SCDF HazMat specialist team, in fully encapsulated High Performance Suits (HPS) and equipped with breathing apparatus sets, plugged the source of the leak. While, another team simultaneously performed vapour suppression operation using 3 water jets.
"This critical operation served to quickly dilute the release of low concentration of chlorine vapour from the leaked cylinder into the surroundings," it said.
All workers from the affected facility and its immediate neighbouring premises were evacuated from the location as a safety precaution.
SCDF stated that a total of 7 individuals, including 2 SCDF officers, were conveyed to Ng Teng Fong General Hospital in 3 ambulances for momentary exposure to the chlorine vapour. They were conscious but experienced eye irritation and difficulty in breathing.
According to the latest readings from the HazMat detectors, no traces of chlorine vapour in the surrounding atmosphere.
Investigations into the incident are now in progress.
Chlorine gas is a toxic respiratory irritant. Airborne concentrations greater than 3-5 ppm by volume are detectable by smell, and exposure to 4 ppm for more than 1 hr can have serious respiratory effects.
Because chlorine gas is denser than air, it stays close to the ground when released. The contents of a 1-ton cylinder of chlorine can cause coughing and respiratory discomfort in an area of 3 square miles. The same amount concentrated over an area of 1/10 square mile can be fatal after only a few breaths.