Singapore enjoyed clearer skies for most of yesterday, but the respite is expected to be short.

Yesterday, the 24-hour Pollutant Standards Index (PSI) stayed mostly within the moderate range of 51 to 100. But it began rising towards the upper end in the afternoon. The three-hour PSI rose from 109 at 2pm to 137 at 9pm.

The National Environment Agency (NEA) forecast the 24-hour PSI to be in the low to mid sections of the unhealthy range of 101 to 200 today. It may enter the high end if unfavourable winds blow in denser haze from Indonesia.

Deputy Prime Minister Teo Chee Hean posted on his Facebook page that he had received a call yesterday from Indonesia's Coordinating Minister for Political, Legal and Security Affairs Luhut Panjaitan.

The latter assured Mr Teo that the Indonesian government is taking the haze very seriously and deploying more troops to deal with the fires that are causing it.

Mr Teo said he reiterated Singapore's offer to assist Indonesia in putting out the fires, and that this would be a sign of cooperation between the two countries.

Haze levels here peaked at a 24-hour PSI reading of 267 to 322, crossing the 301 mark for hazardous air quality, at 8am last Friday - the highest levels since the new PSI was launched in April last year.

On Friday, lessons were stopped at primary and secondary schools, kindergartens and special education schools under the Ministry of Education, and religious schools and kindergartens under the Islamic Religious Council of Singapore.

With the forecast, all schools will resume classes today.

Schools have haze management plans, air purifiers and sufficient enclosed spaces for their students, the ministry said yesterday.

As the 24-hour PSI is expected to stay in the unhealthy range, schools will minimise outdoor activities and exempt students who are feeling unwell or have pre-existing lung or heart conditions from all physical exercise.

While the better air conditions persisted yesterday, Singaporeans were out cycling, jogging, brisk walking and doing other activities.

Playgroup teacher Clara Wee, 56, went for a 6km walk with her husband at Changi Point, which they completed "with ease".

"The air is much better today and it was especially noticeable during my walk. I could breathe much more easily," she said.

But the haze is expected to remain until November.

Minister of State for National Development and Defence Maliki Osman yesterday made sure residents of Pulau Ubin would be well-equipped with haze protection kits. With volunteers from Siglap grassroots organisations, he distributed WeCare Packs, containing items including N95 masks, lozenges, eyedrops and food items such as instant noodles and canned sardines, to residents there. Thirty residents live on the island that is part of Dr Maliki's constituency in East Coast GRC.

He made stops at seven households and three shops there, but noted that most households had received N95 masks from the Siglap grassroots leaders. Those who have not will get them soon.

A mask collection point has also been set up at a bicycle shop near the jetty, run by the village chief, Mr Chu Yok Choon, 70.

Madam Huang Ya Shan, 77, who received a WeCare Pack, was thankful for the items.

"It shows they care or they wouldn't have come all the way to give it to me personally," said the drink stall owner.