Students in Selangor, Negeri Sembilan and Malacca as well as federal territories Kuala Lumpur and Putrajaya stayed home yesterday, after Malaysia was forced to close more than 2,000 schools due to the haze.
This came after the Air Pollutant Index (API) in some of the areas neared "very unhealthy" levels, leading to cloud-seeding operations to keep worsening haze conditions at bay.
The decision to close the 2,045 schools across the affected areas was made on Monday after the API rose to 195 and is expected to rise further, said Malaysian Education Minister Mahdzir Khalid yesterday.
The latest move by the ministry affected some 1.5 million students but Mr Mahdzir said the schools will reopen if API levels fall to 150.
Malaysia's API and Singapore's Pollutant Standards Index are closely related. Any reading above 200 is considered very unhealthy, while 300 and above are hazardous.
According to national health and environment protocols, schools must close when the API hits 200.
The Education Ministry, however, has issued a directive for schools to stop all outdoor activities when the API is higher than 150.
Yesterday, the Meteorological Department (Met) began a three-day cloud-seeding operation using planes from the Royal Malaysian Air Force in the afternoon.
One aircraft, which flew out of Subang, just outside Kuala Lumpur, released rain-inducing chemicals over the Klang Valley, Perak, Pahang, Negeri Sembilan and Malacca, while another covered Sarawak.
"Rain is expected a few hours after the process," the Met's atmospheric science and cloud-seeding director, Ms Maznorizan Mohamad, told state news agency Bernama. She said the operation would continue until tomorrow, depending on cloud availability and weather conditions.
Low visibility due to the haze has also affected flights in Malaysia.
The Department of Civil Aviation ordered Kerteh Airport in Terengganu to close from 10am yesterday after visibility worsened - with the API hitting 190.
Flights in and out of Kuala Lumpur have also been disrupted.
Low-cost carrier AirAsia said around 29 flights were either delayed, diverted or cancelled on Monday because of the haze, while others in Penang and Sarawak have also been affected in the past week.
Prime Minister Najib Razak's scheduled trip on a helicopter yesterday from Kuching to Sematan, 107km east in the interior of Sarawak, was aborted owing to the haze and he had to travel to the settlement by road.