The haze could get worse today, even creeping into the mid-section of the "very unhealthy" range depending on winds.

Yesterday, hazy conditions persisted throughout the day, peaking in the late morning. At both 10am and 11am, the 24-hour Pollutant Standards Index was at 186-229, in the "unhealthy" to "very unhealthy" range. The haze eased later, when readings began to fall below the 201 "very unhealthy" mark at 9pm.

According to the advisory by the National Environment Agency (NEA) yesterday evening, haze spreading westward from Kalimantan, where 324 hot spots were detected, continued to be blown to the region surrounding Singapore by prevailing easterly winds.

Today, the winds are forecast to blow from the east or south-east.

"Hazy and reduced visibility conditions are expected to persist," NEA said in the statement, warning that air quality may enter the mid-section of the very unhealthy range if denser haze is blown in.

Yesterday, Singapore's army and civil defence personnel sent to assist the multinational fire-fighting efforts in Indonesia two weeks ago returned home, landing at Paya Lebar Air Base in the afternoon.

The team included a Republic of Singapore Air Force Chinook helicopter and 34 personnel, along with a six-man Disaster Assistance and Relief Team from the Singapore Civil Defence Force (SCDF).

In the two weeks, the helicopter, equipped with a 5,000-litre heli- bucket, discharged over 400,000 litres of water and extinguished more than 50 hot spots in Sumatra.

Indonesian National Board for Disaster Management head Harmensyah thanked the Singapore team in fighting the fires, adding that its efforts "really count".

Second Warrant Officer Vijaikumar, a 41-year-old air crew specialist, said conditions were tough, with visibility dropping to less than 1km at times. "The underground heat was also quite intense at times," he added. "We actually felt the heat while we were setting up the bucket together with the SCDF and rigging team."