Meta Description: Serian’s API exceeded 500 during the Sarawak haze emergency. Learn why homes, schools, offices and workplaces should check indoor PM2.5 instead of relying on visibility alone. Sarawak Haze Emergency: Check Indoor PM2.5 Now Malaysia Sarawak is facing a serious haze emergency. On 4 September 2026, an emergency was declared in Serian District after the Air Pollutant Index exceeded 500. Reuters reported an API reading of 519, while other reports placed the reading between 515 and 521 at different times during the day. An API above 300 is hazardous. A reading above 500 represents an exceptionally severe air-pollution situation requiring immediate attention from the authorities and affected communities. Kuching, Samarahan, Sri Aman and other parts of Sarawak also experienced unhealthy, very unhealthy or hazardous conditions during the haze episode. Residents and organisations should continue checking the latest official readings because the API can change from hour to hour. However, the official API cannot reveal the precise air quality inside every home, classroom, office, clinic, shop or factory. A portable PM2.5 air quality monitor helps users check conditions where people are actually spending their time. Why the Sarawak Haze Requires Immediate Attention Haze is not only a visibility problem. Smoke can contain fine airborne particles capable of entering buildings through: Open doors and windows Ventilation systems Air-conditioning fresh-air intakes Gaps around doors and windows Frequently used entrances Warehouse loading bays Factory roller shutters Vehicle movement around a building A room may look clearer than the outdoor environment while still containing an elevated concentration of particles. Visibility and smell cannot accurately determine indoor PM2.5. Measurement is needed to understand the actual condition at a particular location. What Does an API Above 500 Mean? Malaysia’s API categories are generally classified as follows: API ReadingAir Quality Status0–50Good51–100Moderate101–200Unhealthy201–300Very unhealthy301–400Hazardous401–500HazardousAbove 500Hazardous emergency level The Serian reading exceeding 500 led to an official emergency declaration covering the district. This is substantially more serious than a normal seasonal haze alert. Residents and businesses must follow current instructions issued by the Malaysian and Sarawak authorities. Portable instruments must not be used to override government advisories, closure orders or health instructions. Why Check Indoor PM2.5 When the API Is Already Available? The official API describes the broader outdoor air-quality condition around a monitoring area. An indoor PM2.5 monitor measures particles at the exact place where it is positioned. For example, the following spaces may produce different results even when they are located within the same district: A bedroom with closed windows A living room using an air purifier A naturally ventilated classroom An enclosed office A shop with customers entering continuously A factory loading area A clinic waiting room A warehouse with open shutters The official API and indoor PM2.5 reading answer different questions. API asks: How polluted is the general outdoor air in this area? A PM2.5 monitor asks: What is the particle concentration at this particular location? Both are useful during a severe haze event. What Is PM2.5? PM2.5 refers to fine particulate matter with a diameter of 2.5 micrometres or smaller. These particles may be produced by: Forest fires Peat fires Open burning Vehicle exhaust Industrial combustion Other smoke-producing activities A PM2.5 monitor normally displays the measured concentration in micrograms per cubic metre—µg/m³. This value should not be compared directly with the API number. API is an index, while PM2.5 is a particle-concentration measurement. Who Should Consider Indoor PM2.5 Monitoring in Sarawak? Homes Families can check bedrooms, living rooms and areas using air purifiers. Measurements can help determine whether: Outdoor haze is entering Closing windows reduces particle levels One room is cleaner than another The air purifier is working PM2.5 increases when the main door opens Schools and Childcare Centres Schools should follow all official closure and operating instructions. Where buildings are allowed to operate, PM2.5 monitoring can support checks in classrooms, libraries, staff rooms and indoor waiting areas. Local readings provide supporting information but do not determine whether a school should open or close. Offices Office facility teams can compare reception areas, meeting rooms, open offices and rooms near external entrances. A model that also measures CO鈧 may be helpful when many employees remain inside an enclosed room with the windows closed. Factories and Warehouses Factories can monitor: Administration offices Control rooms Worker rest areas Production spaces Security posts Loading bays Areas near roller shutters Workplaces must follow official haze and occupational-safety instructions. A general air quality monitor does not replace a formal workplace exposure assessment. Clinics and Care Facilities Indoor monitoring can help facility teams identify particle changes in waiting rooms, reception areas and occupied spaces. Medical decisions should always be made by qualified healthcare professionals. How to Check Indoor PM2.5 During the Sarawak Haze Step 1: Check the Latest Official API Do not depend on a screenshot taken several hours or days earlier. Check the latest official air-quality information and record: Location API reading Date Time Official instructions The API may improve or deteriorate rapidly. Step 2: Select Representative Rooms Do not measure only beside an air purifier or in the cleanest room. Check frequently occupied areas and places where outdoor particles may enter. Step 3: Position the Monitor Correctly Place the PM2.5 monitor: In an occupied part of the room At a representative height Away from direct sunlight Where air can circulate around the sensor Avoid placing it directly: Beside an air purifier outlet Under an air-conditioning vent Against an open window Near cooking smoke Beside vehicle exhaust Inside a cabinet Step 4: Allow the Reading to Stabilise After moving the monitor from one location to another, allow it to respond to the new environment according to the manufacturer’s instructions. Step 5: Record the Reading Record: PM2.5 PM10, if available Location Time Door and window status Air-conditioning status Air purifier status Number of occupants Relevant indoor activity Step 6: Repeat the Measurement Haze conditions can change during the day. Repeat the measurements or use an instrument with data logging when a continuous record is required. How to Check Whether an Air Purifier Is Working A PM2.5 monitor can be used to perform a practical before-and-after comparison. Place the monitor in a representative occupied area. Keep it away from the purifier’s clean-air outlet. Record the initial PM2.5 reading. Close external windows and doors where appropriate. Switch on the air purifier. Keep the room conditions consistent. Record PM2.5 at regular intervals. Review whether the reading decreases. If PM2.5 remains high, possible causes include: Purifier capacity is too low The room is too large The filter requires replacement The fan speed is too low Doors or windows remain open Haze is entering continuously The purifier is positioned poorly An indoor activity is generating particles The test is a practical room check, not laboratory certification of the purifier. Which Air Quality Monitor Is Suitable? For immediate haze monitoring, the instrument should measure at least: PM2.5 PM10, preferably Actual numerical concentration Additional useful functions include: Data logging Adjustable alarms Rechargeable battery Temperature and humidity Downloadable records Historical trend display CO鈧 HCHO and TVOC Temtop LKC-1000S+ 2nd Suitable when the user requires: PM2.5 PM10 HCHO TVOC Temperature Humidity Data export This combination is useful for haze monitoring together with broader indoor chemical screening. Temtop M2000 2nd Suitable when the user requires: PM2.5 PM10 CO鈧 HCHO Temperature Humidity Data export This model is particularly relevant to schools and offices where windows are closed and many people occupy the same room. Temtop M10i The Temtop M10i may suit users who want Wi-Fi-based indoor air-quality monitoring and access to historical readings through a mobile device, subject to the specifications and support of the supplied version. A Monitor Does Not Clean the Air An air quality monitor detects and displays pollutants. It does not remove them. The instrument should be used together with appropriate actions such as: Following official haze instructions Keeping relevant openings closed where advised Maintaining air-conditioning systems Using suitable air-cleaning equipment Checking filter condition Managing outdoor activities Applying workplace respiratory-protection procedures Seeking medical attention when required It provides measurement evidence that can support these decisions. Common Mistakes During Severe Haze Depending Only on the Outdoor Appearance Fine particles may remain present even when visibility improves slightly. Assuming Indoor Air Must Be Clean Particles can enter enclosed and air-conditioned buildings. Comparing PM2.5 Directly With API The measurements use different scales. Putting the Monitor Beside the Purifier This may show cleaner outlet air instead of the average room condition. Using a CO鈧-Only Meter for Haze CO鈧 is not PM2.5. The monitor must include a particulate sensor. Following Old API Information During an active emergency, always check the latest official update. Using a Portable Meter to Ignore Official Instructions Local measurements do not cancel emergency declarations, school closures or workplace directives. Measure Indoor Air—Do Not Guess The Serian emergency demonstrates how serious the 2026 Sarawak haze became, with the API exceeding 500 on 4 September. During conditions of this severity, residents and organisations should follow official instructions immediately. Indoor PM2.5 monitoring provides an additional layer of information by showing what is happening inside an individual room or building. It can help users: Detect haze penetration Compare different rooms Check air purifier performance Review filtration Identify affected areas Record changes over time The most effective approach is to combine official API updates, responsible indoor-air management and properly conducted PM2.5 measurements. News references: Reuters – Malaysia declares emergency in Serian due to haze and Channel News Asia – Serian emergency after API exceeds 500. Contact MTM Precision Contact MTM Precision for assistance selecting a PM2.5 Air Quality Monitor for Sarawak haze monitoring in Malaysia. MTM Precision Sdn. Bhd. Showroom & Service Centre No. 29-1 & 29-2, Jalan Bandar 18, Pusat Bandar Puchong, 47160 Puchong, Selangor, Malaysia 馃寪 Website: www.mtmpre.com.my 馃摟 Email: mtmpre@yahoo.com 馃摫 WhatsApp: 016-660 7346