TAIPEI • Four Singaporean tourists have been taken to hospital in Taipei after coming down with carbon monoxide poisoning, according to media reports yesterday.

The incident happened at about 1am yesterday after the tourists, all men in their 20s, showered in an apartment with the windows shut because of the cold, the reports said.

The source of the gas is believed to be a water heater installed in the apartment, which is near the Sun Yat Sen Memorial Hall and belongs to a friend of the Singaporeans.

Firefighters, who arrived at the fifth storey of the apartment building after receiving an emergency call, found the men in the apartment, with the windows already opened.

The concentration of carbon monoxide in the apartment was about 40 parts per million (ppm), slightly higher than the level which is harmful to health (35 ppm).

The men were taken outside the apartment and given oxygen treatment. Besides dizziness, they did not complain of other discomfort. They were taken to hospital for tests to ascertain the carbon monoxide content in their blood.

A person should not be exposed to average carbon monoxide levels of 52ppm for more than 30 minutes, according to World Health Organisation guidelines. The gas is colourless and odourless.

In a similar incident yesterday, five Hong Kong tourists were taken to hospital in Taipei after falling ill with carbon monoxide poisoning, Taiwanese media said.

Two years ago, a family from Singapore suffered carbon monoxide poisoning while on holiday in Taipei. The family of six were staying in an apartment they had rented from a short-stay home-rental service.

They felt faint and unwell, and all six were taken to hospital. They recovered after receiving treatment.

Police found that the concentration of carbon monoxide in the apartment was 50ppm to 60ppm. The source of the gas was believed to be a water heater on the balcony.