'People should stay indoors,' said a spokesperson answering the National Environment Agency's (NEA's) hotline, with the Pollutants Standard Index (PSI) reading 130 at mid-morning and 115 Saturday The all-time high was 226 in 1997.
The NEA advised residents with existing heart or respiratory ailments to reduce physical exertion and outdoor activity.
The NEA started issuing updates every hour instead of once every 24 hours. Air quality is considered moderate when the PSI is between 50 and 100. More than 100 is unhealthy, while 50 and below is considered good.
Childcare centres were keeping their tots indoors with the windows closed and the air conditioning turned on.
'I could hardly breathe when I started work this morning,' said a 44-year-old taxi driver. 'What can I do? I have to drive'.
Southwestern winds have carried the acrid smoke from burning forests for land-clearing on Indonesia's Jambi, Riau and South Sumatra to Singapore and Malaysia.
Motorists complained of greatly reduced visibility and the occurrence of the haze year-after-year from illegal clearing.
Schools have been closed in the worst areas of Kalimantan in Indonesia while residents have been afflicted with respiratory problems, nausea and headaches.
Singapore is sending satellite images of the hot-spot locations to Indonesian authorities to assist them in battling the fires.