Development is reaching even the smallest towns, and air quality is no longer a concern limited to metro cities. To manage this, air-purifying and pollution-control measures are being taken at the individual, government, and industrial levels.
- Motion Sensors
- August 21, 2026
Air Quality Sensors: How They Help Monitor and Maintain Good Air Quality
Development is reaching even the smallest towns, and air quality is no longer a concern limited to metro cities. To manage this, air-purifying and pollution-control measures are being taken at the individual, government, and industrial levels.
In an air-purifying ecosystem, the first point of contact with the air is the air quality sensor. It detects changes in the air and passes this information to other connected devices that can purify the air or inform you about its quality.
This blog looks at how air quality sensors work, what they detect, and how smart sensors can work with other devices to help maintain better indoor air quality.
What Are Air Quality Sensors and How They Work?
Air quality sensors are devices that detect impurities or unwanted particles in the air, such as specific pollutants, dust particles, and the presence of certain gases. They detect changes in the air and convert them into electrical signals that can be processed into readings. Based on these readings, a connected air purifier, ventilation system, smart home system, or even manual action can help improve the air quality.
A sensor does not purify the air on its own. It only detects what is present in the air and reports the changes.
What Can Air Quality Sensors Detect?
A single sensor may measure one type of air pollutant, while a smart air quality device can combine multiple sensors to track several pollutants and air-quality conditions at once.
The pollutants/parameters detected by air quality sensors can include:
Small Particles (PM2.5 and PM10)
PM2.5 and PM10 are tiny particles present in the air. PM2.5 refers to particles with a diameter of 2.5 micrometres or less, while PM10 includes particles up to 10 micrometres. These particles can come from dust, smoke, cooking, construction, and other sources.
Types of Gases
Air quality sensors can detect different gases depending on the type of sensor used.
Carbon dioxide (CO₂) can build up indoors when many people occupy the same room, especially when there is not enough fresh-air exchange. Outdoor CO₂ levels can also vary depending on the surrounding environment.
Carbon monoxide (CO) can come from incomplete fuel combustion, such as when gas or other fuels burn in an area with limited oxygen or poor ventilation. A poorly ventilated kitchen is one example.
Another group is volatile organic compounds (VOCs). These can be released by building materials, paints, furniture, adhesives, cleaning products, and other household items.
Some sensors can also detect gases such as nitrogen dioxide (NO₂), ozone (O₃), and sulphur dioxide (SO₂).
Temperature and Humidity
Temperature and humidity are not pollutants, but they can affect air quality and sensor readings. Changes in temperature or humidity can influence some pollutants and the way certain sensors respond to them. Some sensors are also sensitive to these changes, so measuring temperature and humidity can help improve the accuracy of their readings.
How Do Air Quality Sensors Detect Pollutants?
Optical sensors use light-based methods to detect changes in the air. These methods include light scattering and light absorption, which can help detect certain particles and gases.
How Do Optical Air Quality Sensors Detect Impurities in the Air?
Optical sensors use light-based methods to detect changes in the air. These methods include light scattering and light absorption.
Light Scattering
In a sensor, there is a small chamber through which air is pulled by a tiny fan. The air passes through the chamber and is pushed out from the other side. A light is continuously passed through the chamber. When the air is clean, the light passes through with little change. When a particle passes through the light, it scatters or reflects some of the light towards the sensor. The sensor records these changes and uses them to estimate the number of particles in the air.
Light Absorption
In a sensor, there is a small tube through which infrared light keeps passing. When a gas in the air passes through the tube, it absorbs specific wavelengths of the infrared light. This change in the amount of light reaching the sensor indicates the presence of the gas. The amount of light absorbed can then be used to estimate the concentration of that gas.
NDIR sensors use this principle to detect gases such as CO₂.
How Do Electrochemical Air Quality Sensors Detect Impurities in the Air?
Electrochemical sensors detect gases with the help of a chemical reaction.
Inside a sensor, there is a thin, skin-like sensing layer surrounded by a chemical material. When the air in the room passes through or reaches this layer, the gas present in the air reacts with the chemical material. This reaction creates an electrical signal, which the sensor uses to estimate the concentration of the gas.
How Do MOS Air Quality Sensors Detect Impurities in the Air
Inside a MOS sensor, there is a heated metal-oxide sensing material through which an electric current passes. Oxygen from the air attaches to the surface of this material and changes its electrical resistance. When other gases come into contact with the surface, they react with the oxygen and cause the resistance to change.
The sensor measures this change in resistance and uses it to estimate the presence or concentration of the gas in the air.
How Does an Air Quality Sensor Connect With an Air-Purifying Ecosystem?
A sensor detects the impurities or pollutants present in the air and converts the detected change into an electrical signal. This information can then reach other devices in different ways, depending on how the air-purifying ecosystem is set up.
- Sensor → Air Purifier: The sensor sends the reading directly to a connected air purifier. The purifier can adjust its operation based on the detected air quality.
- Sensor → Monitor → Air Purifier: The sensor sends the reading to a monitor, which displays the air quality. The information can then be used by the connected purifier to respond to the change.
- Sensor → Monitor: The sensor can also send the reading only to a monitor. The person can then take manual action based on the reading, such as opening a window or switching on a purifier.
- Sensor → Smart Home System → Multiple Devices: In a smart home, the sensor can send the information to a central system that connects with different devices. The response does not have to come from an air purifier alone.
The monitor shows the current air-quality condition and can indicate whether the readings are within the expected range or if a particular parameter is high. Based on these readings, a purifier can adjust its operation to help remove certain pollutants.
A smart home system can connect other devices to the same ecosystem. For example, an air conditioner can help manage room temperature, while fans can circulate air. If the system includes ventilation, fans can also help bring in fresh air and remove stale indoor air.
In some industrial settings, the detected air condition may trigger a specific process or control system, such as ventilation or another treatment method suited to the pollutants present.
How Do Air Quality Sensors Help Maintain Air Quality at Different Levels?
Air quality sensors can be used at different levels, from a single room to an entire city or an industrial facility
At an Individual or Room Level
At an individual level, or at a room level, which can include homes, offices, classrooms, and other indoor spaces, air quality sensors can help maintain healthy air quality in the room. They can detect changes in pollutants, gases, temperature, humidity, and other parameters, allowing the required action to be taken.
At a Broader Environmental Level
At a broader environmental level, air quality sensors can help government officials identify where pollution levels are higher. This information can help in deciding how traffic routes should be directed, where green areas such as parks can be placed, and identifying areas that may need stronger pollution-control measures
At an Industrial Level
At an industrial level, air quality sensors can help maintain the level of different gases and other elements that can affect operations. This can be especially useful in environments that are sensitive to chemical reactions, where a rise or fall in the level of certain gases can affect the process.
What Should You Check Before Buying an Air Quality Sensor?
The right air quality sensor depends on where it will be used and what you want it to detect.
Before choosing one, consider a few basic factors.
- What does it detect? Check whether the sensor measures PM2.5, PM10, CO₂, VOCs, specific gases, temperature, humidity, or other parameters you need to monitor.
- Where will it be used? A sensor for a home may have different requirements from one used in an office, industrial space, or outdoor environment.
- How does it connect? If you want the sensor to work with a purifier, HVAC system, or smart home system, check whether they are compatible and can communicate with each other.
- How often does it take readings? Continuous or frequent readings can help track changes in air quality rather than showing only occasional measurements.
- How does it handle calibration? Sensors can change in performance over time. Check how the sensor is calibrated and whether it requires periodic maintenance.
- Where will it be installed? It should be placed where the air being monitored can reach it properly and where its readings are relevant to the space.
- How much area does it cover? A larger space may need more than one sensor.
What Are the Limitations of Air Quality Sensors?
Air quality sensors are useful for tracking changes in the air, but they also have some limitations.
- They do not detect everything: A sensor can only detect the pollutants or parameters it is designed to measure.
- Readings can vary: Temperature, humidity, sensor placement, and other conditions can affect the readings of some sensors.
- They need proper placement: A sensor placed near a direct source of smoke, dust, or airflow may show different readings from the rest of the room.
- They may need calibration: Some sensors may need calibration or maintenance over time to keep their readings reliable.
- Detection is not purification: A sensor only detects and reports the condition of the air. It needs to be connected to a purifier, ventilation system, or another suitable device if an automatic response is required.
Final Thoughts
Like managing the temperature in a room, where connected systems take care of both the environment and your comfort, breathing cleaner air should also be given the same priority. Air-purifying systems can be at the core of this requirement, helping make cleaner indoor air a regular part of how we live and work.
Before you buy an air quality sensor or connect it to an overall ecosystem, do all the checks listed above and make sure the sensor suits your space and requirements. The right setup can help make your home a fresher place to live.
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FAQ'S
No. Air quality sensors only detect and report changes in air quality. A connected purifier or ventilation system can take action based on these readings.
A sensor detects changes in air quality, while a monitor displays or communicates the readings for you to see.
Yes. Sensors designed for CO₂ detection can measure the concentration of carbon dioxide in the air.
Accuracy depends on the sensor type, quality, calibration, placement, and the conditions in which it is used.
It should be placed where it can sample the air of the area you want to monitor, away from direct sources of smoke, dust, or strong airflow.
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