- Air quality
Air Is Invisible, but It Can Still Be Understood
Through environmental observation, on-site measurement, and appropriate sampling and analysis, the Clean Label examines ventilation, airborne particles, chemical pollutants, biological contaminants, and comfort conditions in the spaces where people actually spend time.
- Why testing matters
Odour and Perception Cannot Replace Testing
People spend a large proportion of each day indoors, but indoor air conditions are not fixed.
Outdoor air enters through doors, windows, ventilation, and air-conditioning systems. Occupant activities, finishing materials, furniture, cleaning products, cooking equipment, and indoor humidity can also continually change air conditions.
Some pollutants may have an odour, while others are not readily detected by the senses. The absence of an unusual smell does not necessarily mean that every air-quality indicator is within an appropriate range; detecting an odour also does not identify the type or concentration of a pollutant.
Air quality must be understood through multiple indicators. It cannot be assessed using a single number or personal perception alone.
- What shapes indoor air
What Affects Indoor Air?
01
Outdoor Environment
Traffic emissions, construction dust, nearby combustion sources, pollen, and other outdoor pollutants may enter through doors, windows, or ventilation systems.
02
Ventilation and Air-Conditioning
Outdoor-air supply, return-air arrangements, filter condition, equipment maintenance, and airflow distribution all affect whether pollutants are effectively removed or filtered.
03
Occupancy and Activities
Occupant density, duration of stay, cleaning, cooking, movement, and other activities can affect concentrations of carbon dioxide, airborne particles, and certain pollutants.
04
Building, Fit-outs, and Furniture
Paint, timber work, adhesives, furniture, flooring, and some building materials may continue to release formaldehyde or other volatile organic compounds over time.
05
Combustion and Equipment
Gas appliances, engines, vehicle exhaust, or incomplete combustion may produce carbon monoxide and other combustion-related pollutants.
06
Temperature, Humidity, and Dampness
Temperature and relative humidity affect more than comfort. They can also influence pollutant emissions, condensation, equipment performance, and conditions that support microbial growth.
Area of Assessment
Ventilation and Occupant Density
Common Parameter
Carbon Dioxide CO₂
What It Helps Explain
Indicates how the space is being used and whether ventilation may require further adjustment.
Area of Assessment
Combustion-related Pollution
Common Parameter
Carbon Monoxide CO
What It Helps Explain
Helps identify whether abnormal combustion-related air conditions may be present.
- Core testing items
Different Indicators Explain Different Aspects of Air Quality
Testing parameters are selected according to the use of the space, its users, equipment, and potential risks. The following are common areas of assessment; they do not mean that every premises must be tested for every parameter.
Area of Assessment
Comfort and Environmental Conditions
Common Parameters
Temperature and Relative Humidity
What They Help Explain
Help explain conditions related to occupant comfort, pollutant emissions, condensation, and microbial growth.
Area of Assessment
Premises-specific Environmental Parameters
Common Parameters
Ozone, Radon, or Other Specified Pollutants
What They Help Explain
Selected according to equipment, the use of the premises, applicable regulations, or specific risks.
Area of Assessment
Chemical Pollutants
Common Parameter
Total Volatile Organic Compounds TVOC
What It Helps Explain
Provides an overall indication of multiple volatile organic compounds; analysis of specific substances may still be required when appropriate.
Area of Assessment
Biological Contaminants
Common Parameters
Bacteria and Fungi
What They Help Explain
Help assess airborne biological particles and issues associated with dampness, cleaning, air-conditioning systems, or mould.
Area of Assessment
Airborne Particles
Common Parameters
PM2.5 and PM10
What They Help Explain
Indicate concentrations of airborne particles in different size ranges and the effects of outdoor pollution, dust, cleaning, and occupant activities.
Area of Assessment
Chemical Pollutants
Common Parameter
Formaldehyde HCHO
What It Helps Explain
Helps identify ongoing emissions that may arise from indoor finishing materials, timber work, furniture, adhesives, and certain building materials.
Actual testing parameters, sampling periods, methods, and assessment criteria are governed by the requirements of the applicable country and region, the officially issued certification criteria, and the testing scope confirmed for the premises.
- UNDERSTANDING EACH INDICATOR
How Should Common Indoor-Air Indicators Be Read?
CO₂
Carbon Dioxide
Human respiration gradually increases indoor carbon-dioxide concentrations, so CO₂ is often used to observe occupant density and ventilation conditions.
Interpretation boundary: CO₂ alone cannot represent every air-pollution issue. Even when it is within an appropriate range, this does not mean that airborne particles, formaldehyde, or other pollutants also meet requirements.
CO
Carbon Monoxide
Carbon monoxide may be associated with combustion equipment, engines, vehicle exhaust, incomplete combustion, or inadequate ventilation. Because it is not readily detected by people, it should be included in an assessment where equipment and potential risks make it relevant.
Interpretation boundary: Testing does not replace maintenance of gas appliances, alarm systems, or everyday safety management.
PM
PM2.5 and PM10
Airborne particles may come from outdoor air or be generated indoors by cooking, cleaning, dust, equipment, and occupant activities. PM2.5 and PM10 refer to particles within different size ranges.
How to read the results: Sampling time, outdoor conditions, air-conditioning operation, and indoor activities at the time of testing should be considered together.
HCHO
Formaldehyde
Formaldehyde may come from timber work, furniture, adhesives, coatings, and some finishing materials. Materials may continue to emit formaldehyde for a period after refurbishment is completed.
Conditions affecting variation: Concentrations may be influenced by temperature, humidity, ventilation, and the amount of material used, so results may differ across seasons or conditions of use.
TVOC
Total Volatile Organic Compounds
TVOC provides an overall indication of multiple volatile organic compounds indoors, but it does not directly identify the type, concentration, or risk of every individual compound.
Further analysis: Where results, the use of the premises, or odour conditions indicate a need for more information, specific substances should be analysed separately.
BIO
Bacteria and Fungi
Results may be affected by occupant activities, cleaning practices, relative humidity, water leaks, condensation, air-conditioning systems, and the outdoor environment.
How to read the results: Results are closely related to the sampling method, culture conditions, and sampling time. Fungal results may also require comparison of indoor and outdoor fungal profiles and environmental conditions; a single number is not sufficient.
T / RH
Temperature and Relative Humidity
These are fundamental indicators for comfort and environmental management. Persistently high relative humidity may increase conditions associated with condensation, dampness, and microbial growth, while very low humidity may cause occupants to experience dryness and discomfort.
How to read the results: Interpretation should reflect the use of the space and seasonal conditions.
- Different places, different priorities
Different Premises Have Different Air-Testing Priorities
01
Hotel Guest Rooms and Residential Spaces
Focus is placed on ventilation, airborne particles, volatile substances associated with fit-outs, temperature and humidity, air-conditioning equipment, and dampness in guest rooms or specified shared areas.
02
Classrooms and Offices
Particular attention is given to carbon dioxide, ventilation, airborne particles, temperature and humidity, and air-conditioning operation. Testing times should reflect normal conditions of use wherever possible.
03
Hospital Wards and Care Settings
Planning reflects the use of the space, user characteristics, air-conditioning arrangements, cleaning and disinfection procedures, and infection-control requirements. It does not replace professional measures required by law.
04
Specialised Enclosed Spaces
Cooking, combustion, cooking fumes, occupant activities, and cleaning may affect airborne particles, carbon monoxide, volatile substances, and ventilation conditions.
05
New or Newly Refurbished Spaces
Formaldehyde, TVOC, airborne particles, and ventilation-related parameters are evaluated according to building materials, furniture, completion date, ventilation method, and anticipated use.
- How air testing works
How Is Air Testing Conducted?
Confirm the Premises and Scope
Understand the use, layout, timing, occupancy, air-conditioning systems, and potential pollution sources.
選擇代表性位置
依空間用途、氣流、設備分布與人員活動選擇位置。
記錄採樣條件
記錄日期、門窗、空調、人數、活動及其他影響條件。
現場量測或採樣
依項目與適用方法進行量測、空氣採樣或樣品收集。
分析與結果判定
對照適用標準、認證規範、條件及已確認範圍。
- Reading the result
Numbers Must Be Considered Together with the Testing Conditions
Air quality changes with occupancy, activities, doors and windows, air-conditioning, outdoor conditions, and seasons. When reviewing results, confirm:
Certification Information Should Clearly Identify
Which space was tested
Where the instrument or sampling point was located
The date and time of testing
Whether the space was occupied at the time
The operating condition of doors, windows, and air-conditioning
The testing method used
Whether the value is instantaneous, an average, or a maximum
The standard and version used for assessment
Results Based on Different Time Periods Should Not Be Compared as Equivalent
Different pollutants may use one-hour, eight-hour, 24-hour, or other averaging periods. Values based on different time periods cannot be compared directly.
On-site screening can support everyday management and an initial understanding. Formal regulatory or certification assessment must follow the applicable methods, sampling conditions, and reporting requirements.
A report should not be read only by asking whether a number is below a particular value. The testing conditions must also be considered.
- Signals worth noticing
What Can People Using a Space Look Out For?
People using a space do not need to identify pollutants themselves, but they can pay attention to the following environmental conditions.
The space feels stuffy when it remains enclosed or becomes crowded
Unusual or irritating odours persist
Dampness, condensation, or mould appears on walls, ceilings, furniture, or around air-conditioning equipment
Air-conditioning filters or outlets have not been cleaned for an extended period
Air conditions change noticeably after cooking, cleaning, or construction work
Abnormal conditions occur near gas appliances
These observations are not equivalent to formal test results, but they can indicate a need for ventilation, equipment inspection, or further environmental assessment.