Klang Valley Haze: PM2.5 Monitoring Plan for Factories and Warehouses Malaysia
Klang Valley Haze: PM2.5 Monitoring Plan for Factories and Warehouses Malaysia
When haze affects Klang, Shah Alam, Banting and other industrial areas in Selangor, factories and warehouses should not depend on one PM2.5 reading taken at the main office.
A large facility can have very different particle levels around:
Production areas
Warehouses
Loading bays
Offices
Canteens
Guardhouses
Worker rest areas
A practical monitoring plan should compare several representative zones and record how conditions change during the workday.
Why One Measurement Is Not Enough
Factories and warehouses have different airflow patterns from homes and small offices.
Indoor PM2.5 can be affected by:
- Open loading-bay doors
- Vehicle and forklift movement
- Mechanical ventilation
- Production processes
- Raw-material handling
- External traffic
- Construction activity
- Frequent employee movement
- Air-conditioning and filtration systems
- Outdoor haze entering the building
A low reading in the administration office does not automatically mean that the warehouse, loading area or guardhouse has the same condition.
Start With a Monitoring Zone Plan
Divide the premises into several practical zones.
Zone 1: Administration Office
This provides a reference for a more enclosed or air-conditioned area.
Check whether:
- Windows are closed
- External doors are frequently opened
- Air purifiers are operating
- Air-conditioning filters are maintained
- Outdoor air is entering through ventilation systems
Zone 2: Production Area
The production area may contain both outdoor haze and internally generated particles.
Record which machines or processes are operating during the measurement.
Do not automatically assume that every high PM2.5 reading comes from regional haze.
Zone 3: Warehouse Storage Area
Take measurements:
- Near the main storage racks
- Away from the loading entrance
- Near external walls
- In internal storage sections
- At areas occupied by warehouse personnel
This helps determine whether outdoor particles are entering only around the loading bay or spreading throughout the warehouse.
Zone 4: Loading Bay
Loading bays often remain open and can be strongly affected by outdoor conditions.
Vehicle movement may also disturb settled dust.
Compare the loading-bay reading with an internal warehouse location.
Zone 5: Canteen and Rest Area
Cooking can produce fine particles that affect the PM2.5 reading.
Record whether food preparation is taking place during the measurement.
A high result in the canteen should not immediately be attributed only to outdoor haze.
Zone 6: Guardhouse
Guardhouses are often located close to:
- Road traffic
- Vehicle entrances
- Open windows
- External doors
- Idling vehicles
The guardhouse reading may therefore differ significantly from the main office.
Use a Consistent Measurement Method
For more meaningful comparisons, keep the procedure consistent.
Use the Same Monitor
Using the same portable PM2.5 monitor across all zones reduces differences caused by using several models with different response times or calculation methods.
Use a Similar Measurement Height
Position the monitor around normal breathing height in an occupied area.
Avoid placing it on the floor, directly above machinery or beside an exhaust outlet unless that location is being investigated intentionally.
Allow the Reading to Stabilise
Do not record only the first number displayed after moving the monitor.
Allow the instrument to respond to the new environment before recording the result.
Record the Time and Activity
The measurement record should include:
- Date
- Time
- Monitoring zone
- PM2.5 reading
- Outdoor API condition
- Doors and windows status
- Air-conditioning status
- Air-purifier status
- Production activity
- Vehicle or loading activity
- Weather condition
This information helps management understand why the reading changed.
Outdoor Haze or Factory Process?
A portable air-quality monitor cannot automatically identify the exact particle source.
Use the pattern of readings to support the investigation.
Outdoor Haze May Be a Major Contributor When:
- PM2.5 rises across several buildings
- Readings increase when external doors open
- Loading bays and guardhouses record higher results
- Indoor readings follow changes in outdoor conditions
- Enclosed filtered rooms show lower readings
An Internal Process May Be a Major Contributor When:
- Only one production zone shows a high reading
- PM2.5 increases when specific equipment operates
- The reading decreases after the process stops
- Offices remain stable while the production area rises
- The increase occurs even when outdoor air quality improves
Further investigation may be required if internal activities generate dust, smoke or fumes.
PM2.5 Monitoring Does Not Replace Occupational Assessment
A general indoor air-quality monitor is useful for:
- Screening
- Comparing zones
- Checking trends
- Evaluating basic controls
- Identifying areas requiring further attention
It does not automatically replace:
- Occupational hygiene sampling
- Personal exposure monitoring
- Process-specific dust measurement
- Gas detection
- Regulatory environmental monitoring
- Professional risk assessment
Factories should determine whether the objective is general haze monitoring or formal workplace exposure assessment.
What Actions Can Be Evaluated?
PM2.5 monitoring can help check whether conditions improve after:
- Closing unnecessary external doors
- Reducing uncontrolled outdoor air entry
- Operating suitable air filtration
- Checking air-conditioning filters
- Moving workers to a cleaner rest area
- Changing the location of an air purifier
- Separating dusty work from occupied spaces
- Adjusting loading activities where practical
Repeat the measurement under similar conditions to determine whether the action produces a consistent improvement.
PM2.5 Is Not a Gas Measurement
PM2.5 monitors measure airborne particles.
They do not replace detectors for:
- Carbon monoxide
- Combustible gas
- Oxygen deficiency
- Hydrogen sulphide
- Ammonia
- Volatile organic compounds
- Other specific industrial gases
Factories with potential gas hazards require the correct sensor and approved safety procedure.
Portable or Fixed Monitoring?
A portable monitor is useful when the EHS or facilities team needs to inspect several zones.
A fixed or continuous monitor may be considered when:
- One critical area requires regular observation
- Conditions change throughout the day
- Management needs historical records
- The room is continuously occupied
- Filtration performance must be monitored regularly
The best choice depends on the facility layout and monitoring objective.
Selecting an Air-Quality Monitor
Before purchasing, confirm:
- Required parameters
- Number of monitoring zones
- Portable or continuous use
- Whether data recording is required
- Who will review the readings
- Whether gas detection is also needed
- Whether the application is general screening or formal assessment
MTM Precision supplies Temtop air-quality monitors for factories, warehouses, offices and other indoor environments.
Customers may WhatsApp us their facility type, intended monitoring zones and required parameters for suitable model selection.
MTM Precision Sdn Bhd
Showroom & Service Centre: No. 29-1 & 29-2, Jalan Bandar 18, Pusat Bandar Puchong, 47160 Puchong, Selangor, Malaysia
Tel: 03-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
Website: www.mtmpre.com.my
06 Oct 2026
