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Sensors are devices that detect and measure specific environmental parameters, such as temperature, humidity, or the concentration of pollutants in the air. In the context of indoor air quality (IAQ), sensors play a crucial role in monitoring and assessing the conditions within buildings.
'''Indoor air quality sensors''' measure specific pollutants or environmental conditions, such as carbon dioxide, particulate matter, temperature, and humidity. A monitor may contain several sensors and display or record their readings.


== Types of Sensors ==
These measurements help identify changes in indoor conditions and assess the effects of ventilation, air cleaning, and everyday activities. Each monitor measures only the parameters it is designed to detect, so no single reading provides a complete picture of indoor air quality.
There are various types of sensors used for IAQ monitoring, each designed to measure different parameters:


* '''Carbon Dioxide (CO2) Sensors:''' CO2 sensors measure the concentration of carbon dioxide in the air, which is a good indicator of ventilation effectiveness. High CO2 levels can indicate poor ventilation and potential buildup of other pollutants.
== Sensor Types and Limitations ==
* '''Volatile Organic Compound (VOC) Sensors:''' VOC sensors detect the presence of volatile organic compounds, which are chemicals emitted from various sources like building materials, furniture, and cleaning products. Some VOCs can have adverse health effects.
{| class="wikitable"
* '''Particulate Matter (PM) Sensors:''' PM sensors measure the concentration of [[particulate matter]] in the air, which are tiny particles that can be inhaled and cause respiratory and cardiovascular problems. PM2.5 sensors specifically measure fine particles that are 2.5 micrometers or smaller in diameter, which are of particular concern for health.
! Parameter !! Common Sensing Method !! Uses and Limitations
* '''Temperature and Humidity Sensors:''' These sensors measure the temperature and relative humidity of the air, which are important factors for thermal comfort and can influence the growth of mold and other biological pollutants.
|-
| '''Carbon dioxide (CO2)'''
| Infrared sensing, commonly non-dispersive infrared (NDIR).
| Helps assess ventilation in occupied spaces. Readings depend on occupancy, outdoor CO2, and air distribution. CO2 does not indicate all indoor pollutants.
|-
| '''Particulate matter (PM2.5 and PM10)'''
| Optical sensors estimate particle concentrations from scattered light.
| Useful for tracking changes related to cooking, smoke, and outdoor particles. Results depend on particle properties and humidity; sensors do not identify particle composition.
|-
| '''Volatile organic compounds (VOCs)'''
| Many consumer monitors use metal oxide sensors to produce a VOC index or estimated total VOC (TVOC) value.
| Useful for detecting changes in gas mixtures. These readings generally do not identify individual chemicals or establish their health risk.
|-
| '''Carbon monoxide (CO) and nitrogen dioxide (NO2)'''
| Electrochemical sensors are commonly used.
| Monitor specific combustion-related gases. Sensitivity to other gases and environmental conditions can affect results.
|-
| '''Temperature and relative humidity'''
| Electronic temperature and humidity sensors.
| Describe thermal and moisture conditions. Readings can be affected by sunlight, nearby heat sources, and heat generated inside the monitor.
|}
 
'''Safety note:''' A general IAQ monitor does not replace a certified carbon monoxide alarm or smoke alarm.
 
For guidance on understanding concentrations and comparing results with guidelines, see [[Interpreting the Data]].
 
== Choosing a Sensor or Monitor ==
Choose equipment according to the purpose of monitoring. EDIAQI's monitoring guidelines cover technical and practical factors such as performance, maintenance, usability, and data access.<ref name="EDIAQI_D32" />


=== Low-cost sensors ===
* '''Parameters:''' Check that the device measures the pollutants or conditions you need. Distinguish directly measured concentrations from estimated values and indices.
Low-cost sensors have become increasingly popular for IAQ monitoring due to their affordability and ease of use. These sensors typically utilize electrochemical or optical sensing technologies to measure various parameters. While they may not be as accurate as professional-grade equipment, they can provide valuable insights into IAQ trends and help identify potential issues.
* '''Performance:''' Look for stated accuracy, measurement range, response time, and independent testing under relevant conditions.
* '''Usability:''' Consider setup, display readability, power supply, and the needs of the people using the device.
* '''Maintenance:''' Check calibration requirements, sensor lifespan, cleaning instructions, and replacement options.
* '''Data access:''' Confirm that readings can be recorded and exported in a useful format. Check connection requirements and any subscription costs.


=== Importance of Sensor Calibration and Validation ===
Low-cost monitors can support everyday monitoring and comparisons across rooms. More demanding investigations may require specialist instruments or laboratory analysis. Select equipment with performance appropriate to the intended use.
To ensure the reliability and accuracy of IAQ data, it is crucial to calibrate and validate sensors regularly. Calibration involves comparing the sensor's readings to a known reference standard to adjust for any discrepancies. Validation involves testing the sensor's performance in real-world conditions to ensure it is functioning correctly.


== EDIAQI's Role in Sensor Evaluation ==
== Calibration and Maintenance ==
The EDIAQI project is actively involved in evaluating the performance of various low-cost sensors in different indoor environments. The project aims to provide recommendations on the most suitable sensors for IAQ monitoring and develop guidelines for their proper use and maintenance.
'''Calibration''' establishes the relationship between a sensor's readings and a reference. '''Validation''' checks whether the measurements are suitable for their intended use.
{| class="wikitable"
 
|+
Follow the manufacturer's instructions for warm-up, cleaning, calibration, and servicing. Keep records of checks and adjustments, and investigate persistent differences between instruments.
!
 
!
Check the calibration requirements for the exact device and arrange recalibration through the provider when needed. EDIAQI's guidelines recommend clear maintenance instructions and information on how to obtain calibration support.<ref name="EDIAQI_D32" />
!
 
!
Placement and monitoring duration also affect results. See [[Measuring IAQ]] for practical guidance.
 
== Sensor Evaluation in EDIAQI ==
EDIAQI's ''Indoor Air Pollution Observation Toolkit'' describes laboratory and real-world methods for evaluating sensor accuracy, precision, and sensitivity to changing conditions.<ref name="EDIAQI_D31" />
 
== Sensor Device Overview ==
The table summarizes devices described on the linked EDIAQI Wiki pages. Example uses are illustrative, rather than a performance ranking. Parameters and features may vary by model or version.
 
{| class="wikitable sortable" style="width:100%;"
! Device !! What It Measures !! Example Use !! Display and Data Access !! Main Feature
|-
|-
|[[Aranet 4]]
| '''[[Aranet 4]]'''
|
| CO2, temperature, relative humidity
|
| Monitoring CO2 in classrooms, offices, and homes
|
| Portable, battery-powered unit with visual CO2 indicators
| NDIR CO2 sensing in a portable device.
|-
|-
|[[Awair Omni]]
| '''[[Awair Omni]]'''
|
| Particulate matter, VOCs, CO2, temperature, relative humidity, light, noise
|
| Monitoring several indoor conditions in one location
|
| On-device indicators; Wi-Fi and an account for app features
| Combines several measurements in one monitor.
|-
|-
|[[CO2Panel PI]]
| '''[[CO2Panel PI]]'''
|
| CO2
|
| Fixed monitoring in classrooms and offices
|
| Three-color LED indicator; Wi-Fi for recording and displaying data; continuous power required
| Simple visual feedback on CO2 levels.
|-
|-
|[[Dioxcare]]
| '''[[Dioxcare]]'''
|
| CO2, temperature, relative humidity
|
| Portable checks of indoor CO2 conditions
|
| Rechargeable battery, configurable audible alert, limited data storage
| Portable NDIR CO2 monitoring.
|-
|-
|[[Extech CO1O]]
| '''[[Extech CO1O|Extech CO10]]'''
|
| Carbon monoxide (CO)
|
| Spot measurements of CO
|
| Battery-powered handheld meter with a backlit display and audible alert
| Dedicated CO measurement; does not replace a certified household CO alarm.
|-
|-
|[[Foobot]]
| '''[[Foobot]]'''
|
| Particulate matter, VOCs, temperature, relative humidity
|
| Following changes in indoor particles and gases
|
| LED indicator, Wi-Fi connection, and app access
| Combined particle and VOC monitoring.
|-
|-
|[[Interoperability]]
| '''[[PCE-VOC 1]]'''
|
| TVOC and formaldehyde (HCHO)
|
| Screening changes in VOC and formaldehyde readings
|
| Rechargeable handheld meter with a display and visual alert
| Displays TVOC and formaldehyde readings; does not identify all individual VOCs.
|-
|-
|[[PCE-VOC 1]]
| '''[[URADMonitor MODEL A3]]'''
|
| PM1, PM2.5, PM10, CO2, VOCs, formaldehyde, ozone, temperature, relative humidity, noise
|
| Continuous monitoring of multiple parameters
|
| Powered fixed station with remote data access; no built-in display
| Combines particle, gas, and environmental measurements.
|-
|-
|[[SensorThings API]]
| '''[[Wöhler CDL 210]]'''
|
| CO2, temperature, relative humidity
|
| Recording indoor CO2 and thermal conditions over time
|
| Display, audible alert, data logging, and download to a computer; mains power required for measurements
|-
| Stores measurements for later review.
|[[URADMonitor MODEL A3]]
|
|
|
|-
|[[Wöhler CDL 210]]
|
|
|
|}
|}
== Related Pages ==
* '''[[Measuring IAQ]]:''' Measurement approaches, sensor placement, and monitoring duration.
* '''[[IAQ Data Management]]:''' Organizing, checking, storing, and sharing data, including privacy considerations.
* '''[[Interpreting the Data]]:''' Understanding readings and comparing results with guidelines.
* '''[[IAQ Data Reporting and Visualization]]:''' Presenting results through dashboards, reports, and alerts.
* '''[[SensorThings API]]:''' A standard for exchanging sensor observations between systems.
== References ==
<references>
<ref name="EDIAQI_D31">{{#lst:Reading List|EDIAQI_D31}}</ref>
<ref name="EDIAQI_D32">{{#lst:Reading List|EDIAQI_D32}}</ref>
</references>
For the wiki's agreed literature sources, see [[Reading List]].
[[Category:Sensors]]
[[Category:Sensors and Monitoring Methods]]
[[Category:Sensors and Monitoring Methods]]
[[Category:Measurement Methods]]

Revision as of 10:45, 10 September 2026


Indoor air quality sensors measure specific pollutants or environmental conditions, such as carbon dioxide, particulate matter, temperature, and humidity. A monitor may contain several sensors and display or record their readings.

These measurements help identify changes in indoor conditions and assess the effects of ventilation, air cleaning, and everyday activities. Each monitor measures only the parameters it is designed to detect, so no single reading provides a complete picture of indoor air quality.

Sensor Types and Limitations

Parameter Common Sensing Method Uses and Limitations
Carbon dioxide (CO2) Infrared sensing, commonly non-dispersive infrared (NDIR). Helps assess ventilation in occupied spaces. Readings depend on occupancy, outdoor CO2, and air distribution. CO2 does not indicate all indoor pollutants.
Particulate matter (PM2.5 and PM10) Optical sensors estimate particle concentrations from scattered light. Useful for tracking changes related to cooking, smoke, and outdoor particles. Results depend on particle properties and humidity; sensors do not identify particle composition.
Volatile organic compounds (VOCs) Many consumer monitors use metal oxide sensors to produce a VOC index or estimated total VOC (TVOC) value. Useful for detecting changes in gas mixtures. These readings generally do not identify individual chemicals or establish their health risk.
Carbon monoxide (CO) and nitrogen dioxide (NO2) Electrochemical sensors are commonly used. Monitor specific combustion-related gases. Sensitivity to other gases and environmental conditions can affect results.
Temperature and relative humidity Electronic temperature and humidity sensors. Describe thermal and moisture conditions. Readings can be affected by sunlight, nearby heat sources, and heat generated inside the monitor.

Safety note: A general IAQ monitor does not replace a certified carbon monoxide alarm or smoke alarm.

For guidance on understanding concentrations and comparing results with guidelines, see Interpreting the Data.

Choosing a Sensor or Monitor

Choose equipment according to the purpose of monitoring. EDIAQI's monitoring guidelines cover technical and practical factors such as performance, maintenance, usability, and data access.[1]

  • Parameters: Check that the device measures the pollutants or conditions you need. Distinguish directly measured concentrations from estimated values and indices.
  • Performance: Look for stated accuracy, measurement range, response time, and independent testing under relevant conditions.
  • Usability: Consider setup, display readability, power supply, and the needs of the people using the device.
  • Maintenance: Check calibration requirements, sensor lifespan, cleaning instructions, and replacement options.
  • Data access: Confirm that readings can be recorded and exported in a useful format. Check connection requirements and any subscription costs.

Low-cost monitors can support everyday monitoring and comparisons across rooms. More demanding investigations may require specialist instruments or laboratory analysis. Select equipment with performance appropriate to the intended use.

Calibration and Maintenance

Calibration establishes the relationship between a sensor's readings and a reference. Validation checks whether the measurements are suitable for their intended use.

Follow the manufacturer's instructions for warm-up, cleaning, calibration, and servicing. Keep records of checks and adjustments, and investigate persistent differences between instruments.

Check the calibration requirements for the exact device and arrange recalibration through the provider when needed. EDIAQI's guidelines recommend clear maintenance instructions and information on how to obtain calibration support.[1]

Placement and monitoring duration also affect results. See Measuring IAQ for practical guidance.

Sensor Evaluation in EDIAQI

EDIAQI's Indoor Air Pollution Observation Toolkit describes laboratory and real-world methods for evaluating sensor accuracy, precision, and sensitivity to changing conditions.[2]

Sensor Device Overview

The table summarizes devices described on the linked EDIAQI Wiki pages. Example uses are illustrative, rather than a performance ranking. Parameters and features may vary by model or version.

Device What It Measures Example Use Display and Data Access Main Feature
Aranet 4 CO2, temperature, relative humidity Monitoring CO2 in classrooms, offices, and homes Portable, battery-powered unit with visual CO2 indicators NDIR CO2 sensing in a portable device.
Awair Omni Particulate matter, VOCs, CO2, temperature, relative humidity, light, noise Monitoring several indoor conditions in one location On-device indicators; Wi-Fi and an account for app features Combines several measurements in one monitor.
CO2Panel PI CO2 Fixed monitoring in classrooms and offices Three-color LED indicator; Wi-Fi for recording and displaying data; continuous power required Simple visual feedback on CO2 levels.
Dioxcare CO2, temperature, relative humidity Portable checks of indoor CO2 conditions Rechargeable battery, configurable audible alert, limited data storage Portable NDIR CO2 monitoring.
Extech CO10 Carbon monoxide (CO) Spot measurements of CO Battery-powered handheld meter with a backlit display and audible alert Dedicated CO measurement; does not replace a certified household CO alarm.
Foobot Particulate matter, VOCs, temperature, relative humidity Following changes in indoor particles and gases LED indicator, Wi-Fi connection, and app access Combined particle and VOC monitoring.
PCE-VOC 1 TVOC and formaldehyde (HCHO) Screening changes in VOC and formaldehyde readings Rechargeable handheld meter with a display and visual alert Displays TVOC and formaldehyde readings; does not identify all individual VOCs.
URADMonitor MODEL A3 PM1, PM2.5, PM10, CO2, VOCs, formaldehyde, ozone, temperature, relative humidity, noise Continuous monitoring of multiple parameters Powered fixed station with remote data access; no built-in display Combines particle, gas, and environmental measurements.
Wöhler CDL 210 CO2, temperature, relative humidity Recording indoor CO2 and thermal conditions over time Display, audible alert, data logging, and download to a computer; mains power required for measurements Stores measurements for later review.

Related Pages

References

  1. ↑ 1.0 1.1
  2. ↑

For the wiki's agreed literature sources, see Reading List.

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