Why CO2 Alone Is Not Enough for Indoor Air Quality Monitoring Malaysia
Why CO2 Alone Is Not Enough for Indoor Air Quality Monitoring Malaysia
CO₂ is one of the most useful parameters for investigating ventilation in occupied indoor spaces.
But there is an important limitation:
CO₂ alone does not represent every aspect of indoor air quality.
A room can have a relatively low CO₂ reading while still experiencing elevated PM2.5 or PM10.
Likewise, an air purifier may reduce particulate matter significantly while CO₂ continues to increase in a heavily occupied enclosed room.
For a broader indoor environmental investigation, professionals may therefore need to consider several parameters together.
The TENMARS TM-380 Multi IAQ Monitor measures:
CO₂
PM2.5
PM10
Temperature
Relative humidity
This combination helps users look beyond CO₂ alone when investigating indoor air quality in Malaysia.
What Does CO₂ Tell You?
People continuously produce carbon dioxide through respiration.
When an occupied room has insufficient ventilation relative to the number of occupants, CO₂ concentrations can increase.
This makes CO₂ particularly useful for investigating spaces such as:
Offices
Meeting rooms
Classrooms
Training rooms
Conference rooms
Other occupied indoor spaces
The TENMARS TM-380 uses an NDIR sensor for CO₂ measurement.
What CO₂ Does Not Tell You
CO₂ measurement does not directly tell you the concentration of airborne particulate matter.
It does not measure:
PM2.5
PM10
This becomes important when the building is affected by haze, outdoor pollution, construction or other particulate sources.
A low CO₂ reading should therefore not automatically be interpreted as meaning that every aspect of indoor air quality is satisfactory.
Example: Low CO₂ but High PM2.5
Consider an office during a period of poor outdoor air quality.
The ventilation system introduces outdoor air.
CO₂ may remain relatively low because fresh air is being supplied.
However, if particulate filtration is insufficient for the conditions, PM2.5 may still be elevated.
The result could be:
CO₂: Relatively Low
PM2.5: Elevated
A CO₂-only meter would not detect the particulate condition.
Example: Low PM2.5 but High CO₂
Now consider the opposite situation.
An enclosed meeting room has:
Closed windows
Closed doors
An operating air purifier
Ten occupants
The air purifier reduces PM2.5.
But as the meeting continues, CO₂ increases.
The result could be:
PM2.5: Low
CO₂: Elevated
A particulate-only monitor would miss the ventilation-related information.
This demonstrates why the two measurements should not be treated as substitutes for each other.
Air Purifiers and Ventilation Perform Different Functions
This distinction is especially important when evaluating indoor air quality.
Portable air purifiers are primarily designed to clean or filter indoor air.
Ventilation involves exchanging or supplying air.
Therefore, improving particulate filtration does not automatically mean that CO₂ conditions will also improve.
When evaluating an occupied room, it can be useful to measure both:
PM2.5 → Particulate conditions
and
CO₂ → Ventilation-related conditions
Why This Matters During Malaysia Haze
During haze periods, organisations may try to reduce outdoor particulate entry by:
Closing windows
Keeping doors closed
Using air-conditioning
Operating air purifiers
These actions may help manage particulate exposure.
However, in occupied enclosed rooms, reducing outdoor air exchange can create another issue that should be investigated:
CO₂ accumulation.
This means haze management can involve balancing two different considerations:
Control particulate entry
and
Maintain appropriate ventilation.
Monitoring both PM2.5 and CO₂ provides more information for making those decisions.
Why PM10 Should Also Be Considered
PM2.5 receives much of the attention in air quality discussions, particularly during haze.
But larger airborne particles can also matter.
The TENMARS TM-380 measures PM10 in addition to PM2.5.
PM10 measurement can be useful when investigating:
Construction dust
Renovation
Cleaning activities
Road dust
Outdoor particle entry
A CO₂-only meter provides no information about these particulate conditions.
Temperature Adds Another Part of the Picture
Suppose an office feels cool and comfortable.
Does this confirm good indoor air quality?
No.
Air-conditioning can provide effective cooling while CO₂ is elevated.
Similarly, a comfortable temperature does not tell you whether PM2.5 is high or low.
Temperature is useful, but it should be interpreted as one part of the indoor environmental picture.
Humidity Provides Additional Context
Relative humidity is another useful environmental parameter.
When investigating general indoor environmental complaints, facility teams may want to know:
Is CO₂ elevated?
Is PM2.5 elevated?
Is PM10 elevated?
What is the temperature?
What is the relative humidity?
A multi-parameter monitor provides these measurements from one instrument.
Five Parameters, Five Pieces of Information
A useful way to understand multi-parameter monitoring is to consider what each measurement contributes.
CO₂
Useful for investigating ventilation relative to occupancy.
PM2.5
Useful for fine particulate monitoring, including haze-related applications.
PM10
Useful for broader particulate and dust investigations.
Temperature
Provides information about thermal conditions.
Relative Humidity
Provides information about moisture conditions in the indoor environment.
No single one of these parameters represents everything.
Four Common IAQ Situations
Situation 1: Low CO₂ + Low PM2.5
Conditions may appear relatively favourable at that time and measurement location.
Situation 2: High CO₂ + Low PM2.5
Ventilation relative to occupancy may require investigation.
Situation 3: Low CO₂ + High PM2.5
Particulate sources, filtration or outdoor particle entry may require investigation.
Situation 4: High CO₂ + High PM2.5
Both ventilation and particulate conditions may require further attention.
This simple comparison demonstrates why CO₂ alone cannot describe every IAQ situation.
Office Example
An open office may have relatively low CO₂ because ventilation is adequate.
But an adjacent meeting room may show significantly higher CO₂ when occupied.
At the same time, PM2.5 may differ near the building entrance because of outdoor pollution.
One reading from one location cannot represent the entire building.
A portable multi-parameter meter allows users to investigate different areas.
Classroom Example
Classrooms can have high occupancy relative to room size.
CO₂ monitoring can therefore be useful for ventilation investigation.
But during Malaysia haze periods, particulate matter becomes another important consideration.
A school that measures only CO₂ would not directly know the PM2.5 condition inside the classroom.
Facility Management Example
Facility managers deal with many different complaints:
“The meeting room is stuffy.”
“The office is dusty.”
“The air purifier isn't working.”
“The room feels humid.”
Each complaint may require a different measurement.
A multi-parameter IAQ monitor provides more flexibility for initial investigation.
HVAC Troubleshooting Example
HVAC technicians may need to investigate several related systems and conditions.
For example:
Ventilation
Filtration
Temperature
Humidity
Outdoor particle infiltration
CO₂ provides useful information, but it is only one measurement.
The TENMARS TM-380 gives technicians access to several parameters during the same site inspection.
Measure Changes Over Time
Another limitation of a single measurement is that indoor conditions change.
CO₂ can increase as occupancy rises.
PM2.5 can change when doors open.
Particulate levels may decrease after an air purifier is operated.
HVAC schedules can influence temperature and ventilation.
The TENMARS TM-380 supports manual and automatic recording, allowing users to observe changing conditions over time.
Does This Mean CO₂ Monitoring Is Not Important?
No.
CO₂ remains an extremely useful parameter for occupied indoor environments.
The point is simply:
CO₂ should be interpreted for what it measures and should not automatically be treated as a complete indicator of all indoor air quality conditions.
When particulate pollution, dust, temperature or humidity are also relevant, additional measurements are required.
Why Consider the TENMARS TM-380?
The TENMARS TM-380 combines:
CO₂ + PM2.5 + PM10 + Temperature + Relative Humidity
in one portable instrument.
It also provides:
NDIR CO₂ sensing
Laser particulate matter sensing
CO₂ / PM2.5 / PM10 warning indications
Manual and automatic recording
Rechargeable lithium battery
This makes it suitable for broader indoor environmental investigations where CO₂ alone does not provide enough information.
Multi-Parameter Indoor Air Quality Monitoring Malaysia
Indoor air quality is rarely a one-number issue.
Ventilation may be satisfactory while particulate pollution is elevated.
Particle filtration may be effective while CO₂ increases.
Temperature may be comfortable while other environmental conditions require investigation.
For HVAC contractors, facility managers, schools, building maintenance teams and other professional users in Malaysia, measuring several relevant parameters can provide a more complete understanding of what is happening inside a building.
Contact MTM Precision
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: +6016-660 7346
Contact MTM Precision for TENMARS TM-380 Multi IAQ Monitor enquiries in Malaysia.
13 Aug 2026
