LUMPUR - Toxic haze from Indonesian forest fires closed thousands of schools across the country and in neighboring Malaysia Wednesday, while air quality worsened in Singapore just days before the city's Formula One motor race.
Illegal fires to clear land for agriculture are blazing out of control on Sumatra and Borneo islands, with Jakarta deploying thousands of security forces and water-bombing aircraft to tackle them.
The Indonesian blazes are an annual problem, but this year's are the worst since 2015 and have added to concerns about wildfire outbreaks worldwide exacerbating global warming.
On Wednesday, air quality deteriorated to "very unhealthy" levels on an official index in many parts of peninsular Malaysia, to the east of Sumatra, with the Kuala Lumpur skyline shrouded by dense smog.
Nearly 1,500 schools were closed across Malaysia due to the air pollution, with over 1 million pupils affected, according to the education ministry.
The two worst-affected states were Selangor, outside Kuala Lumpur, where 538 schools were closed, and Sarawak on Borneo, with 337 closures. Hundreds of schools in several other states in peninsular Malaysia were also affected.
Borneo island is divided between Indonesia, Malaysia and Brunei.
A growing number of Malaysians were suffering health problems due to the haze, with authorities saying there had been a sharp increase in outpatients at government hospitals -- many suffering dry and itchy eyes.
Indonesian authorities said hundreds of schools in hard-hit Riau province on Sumatra were shut, without providing a precise number, while about 1,300 were closed in Central Kalimantan province on Borneo.
Poor visibility also caused the cancellation Tuesday of about 40 flights at three airports in Indonesian Borneo.
SINGAPORE SMOG RACE?
Air quality in Singapore worsened to unhealthy levels and a white smog obscured the striking waterfront skyline, featuring the Marina Bay Sands casino resort with its 3 towers and boat-shaped top level.
The worsening pollution increased fears that this weekend's Formula One race may be affected. Organizers say the possibility of haze is one of the issues in their contingency plan for Sunday's showpiece night race, but have not given further details.
The city-state's tourism board said spectators would be able to buy masks as protection from the haze if conditions would not improve.
Assistance would also be provided on-site for spectators who feel unwell, the board's executive director of sports, Jean Ng, told the Today news portal.
"Various Singapore government agencies have been working closely with (the) race organizer... to ensure the delivery of the best race and entertainment experience possible while keeping a watchful eye on the health and well-being of everyone involved," she said.
The Indonesian government has insisted it is doing all it can to fight the fires, with President Joko Widodo saying during a visit to a hard-hit area on Sumatra on Tuesday that "we have made every effort."
But this year's fires have been worsened by dry weather and experts believe there is little chance of them being extinguished until the onset of the rainy season in October.
Indonesia's meteorology, climate and geophysics agency said Wednesday that over 1,000 hotspots -- areas of intense heat detected by satellite that indicate a likely fire -- had been sighted, most of them on Sumatra.
The smog is also affecting endangered orangutans on Borneo, with dozens of the young apes at rescue centers contracting respiratory infections, according to the Borneo Orangutan Survival Foundation.