Schools closed and residents donned smog masks as air pollution from forest and brush fires soared way above danger level in one Indonesian region.
"Measurements taken this morning show the air pollution index reached 1,076, way above the 300 mark that indicates a dangerous level," Adi Yana of the environmental agency in West Kalimantan province on Borneo island said Thursday.
Analysis showed the pollution originated from the burning of organic material, he said.
Many residents in the provincial capital Pontianak, especially motorcycle riders and schoolchildren are wearing masks, he said.
Reports reaching Jakarta said several schools in Pontianak have closed until further notice due to the thick haze.
The meteorology office in the city said morning visibility remained around 500 to 1,000 meters. "I do not really see any substantial improvement compared to yesterday," said Suhardi, the head of the office.
Thick haze also hung over Palangkaraya, the capital of the neighbouring province of Central Kalimantan. The weather office there said visibility remained low at between 300-500 meters.
"We still have winds from the south and southeast but they also carry smoke and therefore they do not help in thinning the haze here," said Hidayat at the office.
Haze was also reported over Banjarmasin in South Kalimantan but weathermen said it was only a thin layer.
The haze, an annual hazard for millions of Indonesians and some of their neighbours, is largely from fires started illegally to clear land for replanting. It has also hit the westernmost island of Sumatra.
"The smoke is becoming visible and we are beginning to smell the acrid smell of fire and our eyes are beginning to suffer from the dust particles," said a weather official in Pekanbaru, the capital of Riau province on the island.
Visibility was around 1,000 meters but was not affecting flights at the local airport, he said.
The latest satellite photos, from Tuesday, showed 205 "hot spots" – indicating actual fires or high-temperature areas – in the Indonesian part of the vast island of Borneo, and 27 in Malaysian Borneo. In Sumatra, 53 "hot spots" were detected.
Research and Technology Minister Hatta Rajasa urged local authorities to prosecute forest concession-holders who set fires to clear land, and to try to educate forest squatters and small farmers who carry out smaller-scale burning.
Rajasa, quoted by the Jakarta Post, said small farmers and squatters – who often did not know they were breaking the law – contributed 70 percent of the haze and concession-holders the remainder. Using fire to clear land has been illegal since 1999 but prosecutions are very rare.
In 1997 and 1998, choking haze caused by forest fires in Indonesia blanketed parts of Southeast Asia for months, causing serious health problems and traffic hazards and disrupting airline schedules.