SINGAPORE - Occasionally hazy conditions can still be expected on Thursday night and on Friday (Aug 20 & 21), the National Environment Agency (NEA) said.
The Pollutant Standards Index (PSI) may also rise to the low end of unhealthy levels again.
"For the rest of today and tomorrow, with the prevailing winds forecast to blow from the southwest, occasional hazy conditions can still be expected," NEA said in statement on Thursday evening.
"The 24-hour PSI is expected to be in the high-end of the moderate range and may enter the low-end of the unhealthy range", if wind conditions persist, it added.
Air quality is considered to be moderate when the PSI readings range from 51 to 100, and unhealthy when it hits 101 to 200.
Slight hazy conditions have been prevalent since Wednesday, and the three-hour PSI hit 103 at 5pm on Thursday (Aug 20).
It fell slightly to 100 at 6pm, then to 82 at 9pm. The 24-hour PSI remained in the moderate range.
There were complaints of a strong burning smell in various parts of the island.
The number of hotspots has increased again in Indonesia's Sumatra and Kalimantan in the past few days, said Dr Sutopo Purwo Nugroho, spokesman of Indonesia's disaster mitigation agency (BNPB), in a Blackberry message.
The southern part of Sumatra is seeing its haze situation worsen as efforts to contain fire has been more focused on the central part of Sumatra, in Riau, the Indonesian province second closest to Singapore.
On Thursday (Aug 20), 720 hotspots were detected in Sumatra and 246 hotspots in Kalimantan, based on the images from the Modis (Terra-Aqua) satellite, according to Dr Sutopo.
The NEA advised members of the public, in particular the elderly, pregnant women and children to avoid exerting themselves outdoors for long periods of time.
Those with chronic lung or heart disease should avoid outdoor activities. The agency advised those who are not feeling well to seek medical attention.
The environment agency also forecast thundery showers for Singapore on Friday morning.