Accordingly, 347 primary and 62 secondary schools in nine districts were closed, affecting more than 150,000 students.
Air quality in several parts of the state was rated as "unhealthy" with the Air Pollution Index reading between 120 and 186 points, according to the Department of Environment.
According to the country's air quality rating, an API reading of zero to 50 is "good," 51 to 100 "moderate," 101 to 200 "unhealthy," 201 to 300 "very unhealthy," and 301 and above is "hazardous."
The schools will be closed immediately if the API reading in a district rises beyond 200.
Meanwhile, parts of Peninsula Malaysia recorded an API between 102 and 195 with the worst hit being Rompin district in Pahang state, while the capital Kuala Lumpur recorded an API of 158.
Sarawak authorities have provided 500,000 face masks for locals.
Meanwhile, the Malaysian government is planning to seed clouds to make rain as air quality in many areas of the country has reached unhealthy levels due to smog from forest fires in neighbouring Indonesia.
Smog regularly covers parts of Southeast Asia during the dry season when burning is used by Indonesian people to clear land for palm oil and other crops.