Choking haze enveloped Indonesia's Riau province, disrupting flights and closing schools, as meteorologists warned that there is no relief in sight until next month at the earliest.
The thick smoke filled skies as far away as Penang in Malaysia where the state government started handing out surgical masks yesterday to primary schoolchildren.
At Sultan Syarif Kasim II airport in the Riau provincial capital of Pekanbaru, visibility plummeted to 200m yesterday morning, the worst so far this year. Planes are not permitted to land unless visibility is at least 1,000m.
The air quality in parts of Riau province, including Panam, also turned dangerous. The Pollutant Standard Index (PSI) soared to 436, the highest level of the year. In fact, at least six of the 14 districts and cities in Riau were coded black, denoting the most hazardous PSI levels. In Pekanbaru, the PSI hit a "very unhealthy" red level of 282 yesterday.
"Riau will only see the rainy season in October or November," Mr Sugarin, head of the meteorological office at the Pekanbaru airport, told The Straits Times by phone.
Riau has been hit badly because not only are there fires within the province, but winds are blowing in haze from fires in Jambi and South Sumatra province as well, he said.
By early yesterday, Sumatra had 708 hot spots, with 177 in Riau, 245 in Jambi and 189 in South Sumatra, according to data from Indonesia's disaster mitigation agency (BNPB). The agency has scheduled a press conference in Jakarta this morning to detail Indonesia's fight to contain land and forest fires.
BNPB spokesman Sutopo Purwo Nugroho said in a mobile message: "Land and forest fires in Sumatra and Kalimantan are spreading. Millions of residents are being affected by the haze, which has travelled to parts of Malaysia."
Police in Jambi are investigating five cases of intentional land burning. Three people have been accused of burning 819ha of land in Tebo Ilir district in Tebo regency, the Jakarta Post daily reported.
Schools in Pekanbaru, Kampar and Rokah regencies were closed on Wednesday and yesterday due to the deteriorating conditions.
In Malaysia, meanwhile, the air quality in parts of Kuala Lumpur and Selangor reached unhealthy levels yesterday morning but gradually improved towards the evening.
Malaysia's Department of Environment website said the Air Pollutant Index (API) at the Batu Muda station in Kuala Lumpur was 113 at 9am yesterday. In Cheras and Petaling Jaya, the API was 99. Banting, Port Klang and Shah Alam also recorded unhealthy API levels of 102, 109 and 108 respectively.
In Penang, state official Phee Boon Poh said on Wednesday that surgical masks would be distributed to primary school pupils yesterday and today.
Senior meteorologist Hisham Mohd Anip at the Meteorological Department's National Weather Centre told The Straits Times that Kuala Lumpur should get at least a temporary reprieve.
"We are in the last stage of the south-west monsoon season. The wind is flowing from Sumatra," he said. "Expect it to last for another two to three weeks."