Malaysia closed schools in Kuala Lumpur and other parts of the country on Friday, as haze from fires in neighbouring Indonesia again plunged local air quality to among the world's worst.
Toxic smoke from peatland and forest fires has shrouded cities in the region for more than a month, sending respiratory complaints skyrocketing.
The school closures came as Malaysia's leader discussed the choking smoke with his Indonesian counterpart and called for an urgent regional meeting.
Air quality in Kuala Lumpur has been firmly in "unhealthy levels" this week, with a Swiss-based air quality monitor ranking the Malaysian capital among the world's most polluted cities on most days.
Malaysia's Education Minister Fadhlina Sidek said she has instructed whole school closures in four states and two federal territories as well as one partial closure in the central Pahang State.
"In the future, we will ensure that any decision to close schools is notified in advance so that parents have sufficient time to prepare," Fadhlina said late on Thursday.
Malaysia's King Sultan Ibrahim weighed in on the matter on Thursday, saying schools should be closed as air quality readings reached 150 or higher on the Air Pollutant Index (API).
Under Malaysian guidelines, API readings above 100 are classified as unhealthy, above 200 as very unhealthy, above 300 as hazardous, while readings beyond 500 constitute the threshold for declaring a local emergency.
Kuala Lumpur on Friday showed a reading of around 170 API.
The city was the second-most polluted globally behind neighbouring Singapore on Friday morning, Swiss-based air monitor IQAir said.
Malaysia's Prime Minister Anwar Ibrahim said Thursday he discussed the fire situation with the Indonesian leader Prabowo Subianto.
"The haze issue is indeed at a worrying level. And I have personally contacted President Prabowo," Anwar said.
"And he also agreed to take the necessary steps," Anwar said, without going into specific details.
He said Malaysia has been taking measures to combat the haze, including increasing attempts to trigger rain via cloud seeding.
Experts said the flames are being fanned by a turbo-charged El Nino weather phenomenon, causing the worst pollution conditions in years.
Anwar said he asked Malaysia's Foreign Minister Mohamad Hasan to contact the 11-nation Association of Southeast Asian Nations' secretariat for an urgent meeting between environmental ministers to discuss the matter.
"So these are all the steps we are taking, but we are monitoring and will try the measures that we ought to take next," Anwar said.
Singapore's air quality levels too dipped into the "very unhealthy" range with a reading of 205 on the Air Quality Index, according to the IQAir website.
The AQI converts measurements of pollutants into a single figure indicating air quality and potential health risks.
Readings above 150 are classified as unhealthy, while levels above 300 are considered hazardous.