Sarawak, on Borneo, has been heavily affected by fires on the Indonesian side of the island, with haze forcing school closures in some parts of the state.
Malaysian authorities categorise Air Pollution Index (API) readings above 300 as hazardous, with a measurement of 500 serving as the threshold for declaring an emergency. The API reached 519 in Serian on Friday, government data showed.
The emergency declaration was issued by Malaysia's king, Sultan Ibrahim, after advice from Prime Minister Anwar Ibrahim and Sarawak premier Abang Johari Openg, Anwar's office said in a statement.
"Sultan Ibrahim has consented to the declaration of a state of emergency throughout the Serian district, Sarawak, following haze conditions that have reached a level of air pollution hazardous to public health and safety," the statement said.
Sarawak disaster management committee chairman Douglas Uggah Embas had earlier told a news conference the state had requested an emergency declaration after API readings breached 500.
The emergency would be confined to the Serian district, covering an area of about 20km radius, with essential services such as supermarkets, petrol stations, and banks expected to continue operating, Douglas said.
Cloud-seeding operations were also being carried out, he added.
Malaysia is a constitutional monarchy in which the king has a largely ceremonial role, carrying out his duties with advice from the prime minister and cabinet. But the monarch has the power to decide if an emergency should be declared based on grave threats to national security, the economy, or public order.
