Indonesia has declared a haze emergency in Sumatra's Riau province, as the choking smoke surged way past already hazardous levels and forced thousands to flee Pekanbaru, Riau's capital, which is about 280km away from Singapore.
The deteriorating situation - the result of forest fires in Riau, Jambi and South Sumatra provinces - prompted President Joko Widodo to instruct the police and armed forces chiefs to deploy additional personnel to help combat the haze.
Mr Joko, who is on an official visit to Qatar, also warned in a statement yesterday that the government would take harsh legal action.
"I have also told law enforcers to take stern action against those who are responsible, including confiscating land licences and forestry permits," he said.
In Singapore, the 24-hour Pollutant Standards Index (PSI) readings hovered within the unhealthy range (101-200) throughout yesterday and are expected to worsen. At 9pm, it ranged between 133 and 166. The three-hour PSI was 249.
Mr Chia Aik Song, an associate scientist with the Centre for Remote Imaging, Sensing and Processing at the National University of Singapore, said that while it was difficult to predict how the haze would develop, he noted that a dry spell would worsen the situation. "As long as there is not enough rain to put out the fires, the threat of unfavourable winds bringing smoke from Sumatra across the Strait of Malacca to Singapore will persist."
The 24-hour PSI is predicted to be in the mid to high sections of the unhealthy range but may deteriorate into the low section of the very unhealthy range (201-300) today, said the National Environment Agency (NEA) yesterday evening. Environment and Water Resources Minister Vivian Balakrishnan spoke with Indonesia's Environment and Forestry Minister Siti Nurbaya Bakar yesterday afternoon to further express his concern over the haze situation.
According to the NEA, he also reiterated Singapore's offer of help, which Indonesia has so far declined. Ms Siti said she would consult President Joko again on the offer. She also agreed to share the names of companies suspected of causing the fires when they are confirmed.
Singapore's Ministry of Education has activated haze management measures and will consider closing all schools if the air quality is at the hazardous level, it said on its website.
In Malaysia, the government has ordered schools in Kuala Lumpur, Selangor, Putrajaya, Melaka and Negeri Sembilan to be closed today. Air Pollutant Index readings as of 11pm yesterday showed that air quality in Kuala Selangor had reached a dangerous level of 207, while readings for the rest of Selangor hovered around the 170 range.