SINGAPORE - The Pollutant Standard Index (PSI) yesterday reached its highest reading so far this year, with the readings for the northern and eastern areas recorded at 64 as at 4pm yesterday.

The PSI across the island was between 58 and 64, falling in the "moderate" range. The level of particulate matter (PM) 2.5 - a very fine pollutant which can cause respiratory problems - was at 71 micrograms per cubic metre in the eastern region, the highest among different parts of the island.

Yesterday's hazy skies came as general practitioners TODAY spoke to reported a spike in the number of patients they are seeing for respiratory or skin problems caused by the haze.

In an update on its website, the National Environment Agency (NEA) said the situation will ease gradually in the days ahead.

However, the reprieve could be temporary. "For the following week, Singapore could still experience slight hazy conditions on some days," NEA said.

The haze was due to "an increase in hotspot activities observed over Sumatra" in the past one week. "The current prevailing winds blowing from the southwest or south have transported the haze from fires in southern Sumatra towards Singapore," the agency said.

It added that the prevailing winds are "expected to turn and blow from the southeast or south and bring a gradual improvement" to the hazy conditions from today.

NEA advised everyone to "limit prolonged or heavy exertion". For children, older adults as well as people with heart or lung disease, they were advised to "reduce prolonged or heavy outdoor exertion".

Ms Geraldine Tan, 24, who has sinus problems, said she has been experiencing breathing discomfort. "This usually happens when the haze season rolls around. I'll generally feel very uncomfortable, and start sniffling a lot more," she said.

Dr Tan Tze Lee, a GP at Edinburgh Clinic, told TODAY the number of patients he is seeing with lung discomfort has doubled. Another GP, YS Teo Family Clinic and Surgery's Dr Victor Teo, added: "There has been more cases of upper respiratory tract infections, throat irritation, pre-existing cases of asthma and even cases of eczema over the last couple of weeks."

The GPs advised the public, especially those with pre-existing conditions, not to over-exert themselves outdoors. "They can still exercise, but probably indoors, using the treadmill or weight machine, it's just not advisable to jog outside and breathe in lots of the haze, especially if they have asthma," said Dr Teo.