Meta Description: Learn how Sarawak factories and warehouses can monitor PM2.5 during haze, compare work areas, check air purifiers and identify where outdoor particles enter.

Sarawak Factory Haze Monitoring: Check PM2.5 in Work Areas Malaysia

The severe September 2026 Sarawak haze created immediate concerns for factories, warehouses, workshops and other industrial workplaces.

On 4 September 2026, an emergency was declared in Serian after the Air Pollutant Index exceeded 500. Kuching and several other Sarawak locations also experienced very unhealthy or hazardous conditions during the haze episode.

Factories must follow the latest instructions issued by the authorities and apply their approved occupational-safety procedures.

A portable PM2.5 air quality monitor can provide additional information by showing particle concentrations inside individual work areas.

Why Factory Indoor Air Can Differ From the Official API

The official Air Pollutant Index—API describes regional outdoor conditions.

It cannot show the exact particle concentration inside:

• A production floor

• A control room

• A maintenance workshop

• A warehouse

• A worker rest area

• A security post

• An administration office

• A loading bay

Indoor PM2.5 depends on building design, ventilation, filtration and daily operations.

A closed control room with effective filtration may have a different reading from a loading area where roller shutters remain open.

This is why factories should use official API information and local workplace measurements for their respective purposes.

How Haze Enters a Factory

Fine particles may enter through:

• Roller shutters

• Loading bays

• Open doors

• Windows

• Roof ventilation

• Mechanical ventilation

• Fresh-air intakes

• Wall and roof gaps

• Vehicle entrances

• Employees moving between outdoor and indoor areas

Factories often have larger openings than homes or offices. Outdoor particles may therefore enter quickly during hazardous haze.

Haze May Not Be the Only Particle Source

A factory PM2.5 reading can be affected by both outdoor haze and internal processes.

Possible internal sources include:

• Grinding

• Cutting

• Welding

• Sanding

• Powder handling

• Material transfer

• Diesel equipment

• Forklift exhaust

• Combustion processes

• Sweeping and cleaning

• Packaging activities

• Nearby vehicle movement

A general PM2.5 monitor measures the particle concentration around its sensor. It does not identify the chemical composition or exact source of those particles.

If a workplace needs regulatory exposure testing or analysis of a particular industrial dust, it may require a qualified occupational hygiene assessment and a prescribed sampling method.

Which Factory Areas Should Be Monitored?

Production Areas

Check representative operator positions rather than placing the instrument only at the office entrance.

Control Rooms

Control rooms are often enclosed and air-conditioned. Measurements can show whether they remain better protected from outdoor haze.

Administration Offices

Compare open offices, meeting rooms, reception areas and rooms near external entrances.

Worker Rest Areas

These spaces may be used as cleaner indoor areas during haze. Their PM2.5 should be checked rather than assumed.

Loading Bays

Loading areas can show how strongly outdoor air affects the building when shutters or doors are open.

Warehouses

Measure the centre of the warehouse, areas near entrances and enclosed offices within the warehouse.

Security Posts

Guardhouses may be heavily affected because doors or windows are frequently open and staff remain close to outdoor traffic.

Canteens

Cooking can raise particle readings independently of haze. Record the activity taking place during each measurement.

How to Create a Factory PM2.5 Monitoring Plan

Step 1: Check the Latest Official API

Record the official API for the nearest relevant location, together with:

• Date

• Time

• Air-quality status

• Official workplace instructions

Do not depend on an old API screenshot.

Step 2: Divide the Premises Into Zones

A practical zoning plan may include:

• Outdoor reference area

• Administration zone

• Production zone

• Warehouse zone

• Loading zone

• Cleaner enclosed room

• Worker rest zone

Step 3: Identify Normal Operations

Record whether the measurement is taken during:

• Normal production

• Maintenance

• Cleaning

• Loading

• Shift change

• Lunch break

• Production shutdown

This helps explain changes in the readings.

Step 4: Position the Monitor Correctly

Place the PM2.5 monitor in a representative occupied area.

Avoid positioning it:

• Directly beside an exhaust

• In front of a purifier outlet

• Under an air-conditioning vent

• Immediately next to a machine producing dust

• Inside a cabinet

• Where heat, water or impact may damage it

If investigating a suspected particle source, take one reading near the source and another at the normal worker location.

Step 5: Allow the Reading to Stabilise

After moving the instrument between areas, allow it to respond to the new environment according to the manufacturer’s instructions.

Step 6: Record the Results

Record:

• PM2.5

• PM10, if available

• Measurement point

• Time

• Work activity

• Door and shutter status

• Ventilation status

• Air-conditioning status

• Air purifier status

• Observations

Step 7: Repeat the Measurements

Repeat the survey when:

• Outdoor API changes

• A different shift begins

• Loading starts

• Doors or shutters open

• Production activity changes

• Filters are replaced

• An air purifier is installed

Example Factory Monitoring Record

Use actual instrument readings. Do not enter assumed or estimated values into a workplace record.

Comparing Indoor and Outdoor PM2.5

Where safe and permitted, a factory can take a representative outdoor reading and compare it with indoor work areas.

Avoid measuring directly beside:

• Vehicle exhaust

• Generators

• Smoking areas

• Local open burning

• Process exhaust outlets

• Dust-producing operations

These sources may produce a reading that does not represent the general outdoor condition.

After the outdoor check, allow the monitor to stabilise before recording indoor values.

How to Identify Haze Entry Points

Compare measurements at:

• The external entrance

• Just inside the entrance

• The centre of the building

• The main occupied zone

• A closed room

If PM2.5 is highest near the entrance and gradually decreases further inside, outdoor infiltration may be contributing significantly.

Repeat the measurements with:

• Shutter open

• Shutter closed

• Ventilation operating

• Ventilation stopped, if safely permitted

• Air purifier operating

Only change one factor at a time where possible.

Checking Air Purifiers in Factory Offices

Air purifiers may be useful in enclosed offices, control rooms and worker rest spaces.

To test performance:

1. Position the PM2.5 monitor away from the purifier.

2. Record the starting PM2.5.

3. Close external windows and doors where appropriate.

4. Switch on the purifier.

5. Record the fan-speed setting.

6. Keep room conditions consistent.

7. Record PM2.5 at regular intervals.

8. Review whether the reading decreases.

If there is little improvement, check:

• Filter condition

• Purifier capacity

• Room size

• Door-opening frequency

• Air leakage

• Fresh-air intake

• Purifier position

• Internal particle sources

A practical room check does not replace certified purifier testing.

Reviewing Air-Conditioning and Filtration

An air-conditioned factory office is not automatically protected from haze.

Fine particles may enter through:

• Fresh-air intake

• Poorly fitted filters

• Dirty filters

• Doors

• Windows

• Building gaps

PM2.5 measurements taken before and after filter maintenance can help facility teams determine whether the work produced a measurable improvement.

When comparing results, keep the monitor position and operating conditions consistent.

When Is Data Logging Useful?

Continuous data logging is helpful when a factory needs to determine:

• When PM2.5 starts increasing

• Whether loading creates pollution spikes

• How shift changes affect the building

• Whether air quality worsens overnight

• How long filtration takes to reduce particles

• Whether a control room stays protected

• Whether filter replacement improves results

A trend record is more informative than an occasional photograph of the display.

Should Factories Also Monitor CO₂?

CO₂ and PM2.5 measure different conditions.

• PM2.5 indicates fine-particle concentration.

• CO₂ can provide information related to occupancy and ventilation.

CO₂ may be relevant in:

• Control rooms

• Meeting rooms

• Training rooms

• Enclosed offices

• Worker rest rooms

A factory may reduce outdoor-air entry during haze while continuing to monitor ventilation in occupied enclosed areas.

The Temtop M2000 2nd includes both PM2.5 and CO₂ measurement, making it suitable for this type of general indoor investigation.

Suitable Temtop Models

Temtop M2000 2nd

Suitable for:

• PM2.5

• PM10

• CO₂

• HCHO

• Temperature

• Humidity

• Data export

Recommended for occupied offices, control rooms and meeting spaces where ventilation also needs to be observed.

Temtop LKC-1000S+ 2nd

Suitable for:

• PM2.5

• PM10

• HCHO

• TVOC

• Temperature

• Humidity

• Data export

Relevant when the factory also wants general screening for formaldehyde and volatile organic compounds.

Temtop M10i

Suitable for compatible Wi-Fi-based indoor monitoring and mobile access to recorded trends, subject to the specifications of the supplied version.

Portable Monitor vs Occupational Dust Instrument

A portable indoor air quality monitor is useful for:

• General screening

• Comparing factory zones

• Checking haze infiltration

• Testing air purifiers

• Observing trends

• Supporting maintenance investigations

It may not be sufficient for:

• Personal exposure sampling

• Regulatory compliance testing

• Respirable crystalline silica assessment

• Specific chemical identification

• Process emission testing

• Workplace exposure limit verification

• Legal exposure documentation

These applications may require specialised instruments, defined methods and qualified professionals.

Common Factory Monitoring Mistakes

Measuring Only in the Office

Production, warehouse and loading areas may have completely different conditions.

Assuming Every High Reading Comes From Haze

Industrial processes may also generate particles.

Measuring Directly Beside a Machine

This may help investigate the machine but may not represent the wider work area.

Ignoring Work Activity

A reading taken during shutdown cannot be compared directly with one taken during full production without noting the difference.

Positioning the Meter Beside a Purifier

This can produce an unusually low reading.

Treating a General Monitor as a Compliance Instrument

Screening measurements and regulatory exposure assessments are not the same.

Ignoring Official Instructions

Portable readings do not override government emergency or workplace requirements.

What Should Management Do With the Data?

Measurement results can support decisions about:

• Moving staff to cleaner indoor rooms

• Reviewing loading schedules

• Reducing unnecessary door opening

• Checking filtration

• Replacing filters

• Relocating air purifiers

• Identifying areas requiring further investigation

• Improving the haze-response procedure

• Escalating the matter to safety professionals

Management should interpret the data together with official instructions, operational requirements and occupational-safety responsibilities.

Measure Each Work Area—Do Not Assume

During severe Sarawak haze, conditions outside the factory may be hazardous while indoor readings vary significantly from one area to another.

A portable PM2.5 monitor helps factories:

• Compare production and office zones

• Check cleaner rooms

• Identify particle-entry points

• Evaluate air purifiers

• Review filtration maintenance

• Document changes during a shift

• Decide where further assessment is needed

The official API establishes the regional air-quality status. Local monitoring shows what is happening at the selected workplace location.

Factories should use both appropriately and continue following all official haze and occupational-safety instructions.

Contact MTM Precision

Contact MTM Precision for assistance selecting a PM2.5 Air Quality Monitor for factories, warehouses and industrial workplaces during haze in Sarawak, Malaysia.

MTM Precision Sdn. Bhd.

Showroom & Service Centre

No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia

🌐 Website: www.mtmpre.com.my
📧 Email: mtmpre@yahoo.com
📱 WhatsApp: 016-660 7346