The Serian Division will stay under a state of emergency for the next three days despite an improvement in air quality, with businesses and government offices permitted to continue operations under health precautions.

Sarawak Disaster Management Committee (SDMC) said it is monitoring the situation closely after Serian's Air Pollutant Index peaked at 521 on Sept 4. By 10am on Sept 5, the reading had dropped to 334, still within the hazardous band of 301-500.

SDMC warned that API levels could fluctuate depending on wind direction and hotspot activity. A full assessment will be made after the three-day monitoring window before any recommendation is submitted to Premier Abang Johari Tun Openg and Prime Minister Datuk Seri Anwar Ibrahim on whether to lift or extend the emergency.

Industries, plantations, construction sites and quarries in the affected area may continue operating provided all necessary health safeguards are in place. The public has been advised to avoid outdoor activities where possible, and to wear N95 or at minimum 3-ply masks when going out.

Particular care should be taken for children, senior citizens and vulnerable groups.

Meanwhile, the Department of Environment reported that nine of Malaysia's 16 detected hotspots on Friday were in Sarawak, with the remaining five in Sabah and two in Terengganu. ASMC satellite data showed 139 hotspots in Kalimantan, with moderate to thick haze moving northeast towards Sarawak, Sabah and Brunei.

Six Sarawak locations recorded very unhealthy API as of 1pm Sept 5: Serian (287), Kuching (267), Sri Aman (251), Samarahan (242), Samalaju (202) and Bintulu (201). Seven more registered unhealthy readings.