The National Environment Agency said on Sunday at noon that the air quality for the rest of the day is expected to be better than originally forecast.
It said that the 24-hour Pollutant Standards Index for the rest of the day is expected to be in the "unhealthy" band, rather than the original "very unhealthy" forecast.
This is due to a change in direction of the low-level winds in Singapore. It also noted that the air quality had improved since Saturday night.
Under the revised health advisory for the day, pregnant women, children and the elderly should minimise outdoor activity that lasts for hours. People with chronic diseases esepcially heart or lung disease should avoid all outdoor activity or wear a protective N95 mask if this is unavoidable.
As of noon on Sunday, the 24-hr PSI is in the 88-98 range across Singapore, and the 24-hr PM2.5 is 81-102 microgrammes per cubic metre across the island.