Can Air Conditioning Remove PM2.5 During Haze Malaysia
Can Air Conditioning Remove PM2.5 During Haze Malaysia
During haze, many homes and offices close the windows and switch on the air-conditioner.
The room becomes cooler, but does that mean the PM2.5 level is also lower?
Not necessarily.
Air-conditioning and air purification perform different functions. Some air-conditioning systems may capture part of the airborne dust through their filters, but the result depends on the system design, filter type, condition and outdoor air intake.
A normal air-conditioner should not automatically be treated as a dedicated PM2.5 air purifier.
What Does an Air-Conditioner Mainly Do?
The main functions of an air-conditioning system are generally to control:
- Room temperature
- Humidity to some extent
- Air circulation
- Thermal comfort
Whether it removes fine particles effectively depends on the filtration system.
A basic washable filter may capture larger dust and protect the air-conditioner, but it may not provide the same fine-particle filtration as a suitable air purifier.
Split Air-Conditioner During Haze
Many residential and small-office split air-conditioners mainly circulate indoor air.
Closing the windows may reduce outdoor smoke entry, while the air-conditioner keeps the room cool.
However, indoor PM2.5 may remain elevated because:
- Fine particles entered before the windows were closed
- Smoke continues entering through gaps
- Doors are opened frequently
- Cooking or cleaning produces particles
- The air-conditioner filter is not designed for fine particles
- The filter requires cleaning
- Particles move in from another room
Use a PM2.5 monitor to check the actual result.
Central Air-Conditioning Systems Are Different
Commercial buildings may use central HVAC systems with:
- Outdoor air intake
- Return-air circulation
- Multiple filtration stages
- Building-management controls
- Different operating schedules
During haze, outdoor air may enter through the fresh-air system.
The building’s facilities or HVAC team should understand:
- Where outdoor air enters
- What filtration is installed
- Whether filters are suitable and maintained
- How the ventilation system operates
- Whether adjustments are safe and permitted
Do not block or modify ventilation equipment without suitable technical assessment.
Why Does the Room Feel Better Even When PM2.5 Is High?
Cooling can improve comfort, but temperature and PM2.5 are different measurements.
A cool room may still contain elevated fine-particle levels.
Similarly:
- No visible smoke does not prove PM2.5 is low
- No burning smell does not prove the air is clean
- Strong airflow does not prove fine particles are being removed
- A clean-looking filter does not confirm filtration performance
Measurement is required to understand the particle trend.
Air-Conditioner vs Air Purifier
Function Air-Conditioner Air Purifier
Main purpose Temperature control and air circulation Reduction of airborne pollutants according to its filter design
Cools the room Yes Normally no
Circulates indoor air Yes Yes
PM2.5 removal Depends on system and filter Designed for particle filtration when suitably specified
Removes COâ‚‚ Not automatically No
Performance check Requires system and filter assessment Can be checked using PM2.5 trends
Neither device replaces a dedicated ventilation assessment.
How to Test the Room
Step 1: Record the Initial PM2.5
Before switching on the air-conditioner, record:
- PM2.5
- Room location
- Time
- Windows and doors status
- Outdoor API condition
- Any cooking or cleaning activity
Step 2: Switch On the Air-Conditioner
Keep the monitor in the same position.
Avoid placing it directly under the air-conditioning outlet.
Step 3: Observe the Trend
Check whether PM2.5:
- Decreases
- Remains unchanged
- Increases
- Changes when the external door opens
- Changes when another indoor activity begins
A lower temperature without a lower PM2.5 reading suggests that cooling alone is not solving the particle problem.
Step 4: Add Air Purification
If a suitable air purifier is available, operate it while maintaining similar room conditions.
Position the PM2.5 monitor away from the purifier’s clean-air outlet.
Compare the trend before and after filtration begins.
Why Might PM2.5 Increase When the Air-Conditioner Starts?
Possible causes include:
- Dust disturbed by the airflow
- Dirty filters
- Dust inside the system
- Outdoor air entering through the HVAC arrangement
- Particles moving from another part of the building
- The monitor being placed directly under an outlet
- Another activity starting at the same time
Repeat the test before concluding that the air-conditioner is the only cause.
Check the Air-Conditioner Filter
Follow the manufacturer’s maintenance instructions.
Consider checking:
- Filter cleanliness
- Correct filter installation
- Air intake condition
- Air outlet condition
- Maintenance schedule
- Signs of excessive dust accumulation
Do not install a restrictive filter that is not approved for the system. An unsuitable filter may affect airflow or equipment operation.
Air Purifiers Do Not Solve Ventilation Problems
An air purifier may reduce particles, but it normally does not remove carbon dioxide generated by occupants.
In a crowded closed room:
- PM2.5 may decrease
- COâ‚‚ may continue increasing
Schools, meeting rooms and offices may need to observe both parameters.
The building’s ventilation requirements must still be considered.
Where Should You Measure?
Check more than one area when possible:
- Near the occupied area
- Away from the air-conditioner outlet
- Away from the purifier outlet
- Near—but not directly beside—the external door
- At the opposite side of the room
- In another room for comparison
Use the same monitor and method for every location.
Choosing an Indoor Air-Quality Monitor
For haze applications, select a monitor that measures PM2.5.
Consider additional parameters when required:
- PM10 for broader particle information
- COâ‚‚ for occupancy and ventilation trends
- TVOC for certain volatile compounds
- Formaldehyde for specific indoor concerns
- Temperature and humidity for environmental conditions
MTM Precision supplies Temtop air-quality monitors for homes, offices, schools, clinics, factories and other indoor environments.
Customers may WhatsApp us their room type, air-conditioning arrangement 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
07 Oct 2026
