The Pollutant Standards Index (PSI) hit 401 at 12:00 on Friday (04:00 GMT) - the highest in Singapore's history.
The previous record was from September 1997, during the 1997-1998 South East Asian Haze, when the PSI peaked at 226.
The Singapore government has pointed the finger at nearby Indonesia for the disaster, believing fires were started in a bid to clear land illegally in Sumatra.
Singaporean Prime Minister Lee Hsieng Loong warned, "We can't tell how this problem is going to develop because it depends on the burning, it depends on the weather, it depends on the wind.
"It can easily last for several weeks and quite possibly it could last longer until the dry season ends in Sumatra which may be September or October."
Indonesian President Susilo Bambang Yudhoyono said "all the country's resources" would be mobilised to extinguish the fires.
Image: © Getty
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