A train at Raffles Place MRT station was evacuated after white smoke was seen inside it yesterday.
The smoke, seen at around 12.45pm at the station, was caused by a leaking air-conditioning compressor that released freon gas, rail operator SMRT said.
Freon gas is a non-flammable gas that is also used in refrigerants and aerosol propellants. The inert gas usually does not react with other substances and mild exposure is generally harmless.
"As a safety precaution, all commuters on board the affected train were asked to disembark and board the next train," said SMRT chief communications officer Margaret Teo. "The affected train was withdrawn from service for further checks."
No fire or injuries were reported in the incident, which happened on the East-West Line.
Mr Benny Ong, 27, a sales manager, said he was on the train heading towards Raffles Place station from Tanjong Pagar when he saw smoke in the cabin. It also smelt as if something was burning.
"The smell was quite strong and commuters alighted once the train reached Raffles Place," said Mr Ong, adding that an announcement was made that the train would be stopping at the station for a while.
"There was no chaos, just some anxiety among the commuters."