Air Quality Sensor

An air quality sensor is a device designed to monitor and measure the concentration of airborne pollutants, gases, and particulate matter. These sensors play a crucial role in environmental monitoring, indoor air management, public health, and industrial safety.

"Indoor air pollution" is following the "soot pollution" , "photochemical smog pollution", the emergence of the third environmental pollution. American experts found that there are more than 500 kinds of volatile organic compounds in indoor air, of which there are more than 20 kinds of carcinogenic substances and more than 200 kinds of disease-causing viruses. SUCH is committed to providing high quality air sensors to protect human health. Below is a detailed introduction about air quality sensors.

What Is an Air Quality Sensor?

An air quality sensor is a specialized device designed to measure and monitor various air pollutants, such as carbon dioxide (CO₂), volatile organic compounds (VOCs), formaldehyde (CH₂O), and particulate matter like PM2.5 and PM10. These sensors are used in a wide array of applications, from indoor air monitoring in homes and offices to industrial emissions detection and urban environmental surveillance.

These air quality sensors can be standalone units, embedded in smart building systems, or integrated into IoT platforms. Converting environmental signals into readable data.

How Do Air Quality Sensors Work?

The working principle of air quality sensors varies depending on the target pollutant. Most sensors rely on either electrochemical, optical, infrared, or semiconductor technology.

1. Gas Sensors:

• NDIR (Nondispersive Infrared) sensors measure gases like CO₂ by detecting how much infrared light is absorbed by gas molecules.
• MOS (Metal Oxide Semiconductor) sensors detect gases such as VOCs or formaldehyde by measuring changes in the electrical resistance of a semiconductor when exposed to certain gases.
• Electrochemical sensors measure gas concentrations by generating a current when gas molecules react at an electrode surface.

2. Particulate Matter Sensors:

• These typically use laser scattering technology, where particles in the air scatter a laser beam. The amount and angle of scattering are used to determine the size and concentration of PM1.0, PM2.5, and PM10 particles.

3. Temperature and Humidity Sensors:

• These sensors provide supporting data to understand air quality variations. For instance, high humidity can affect VOC readings or promote mold growth.

Once the pollutants are detected, the sensors process the signals through a microcontroller unit (MCU) and output them through digital (e.g., RS485, Modbus) or analog (e.g., 4–20mA, 0–10V) interfaces for monitoring and control.

Key Components of Air Quality Sensors

The key components of air pollution sensors work together to ensure accuracy, durability, and efficient data transmission. At the heart of the sensor is the sensor probe, which detects specific gases or particles in the air. The data collected by the sensor probe is then processed by the microcontroller unit (MCU), which converts the raw signals into usable information. This data is then transmitted via a signal output interface, which supports various protocols like RS485, Modbus RTU, 4–20mA, 0–10V, or wireless communication via Wi-Fi or Bluetooth, making the sensors suitable for integration into IoT systems. For real-time monitoring, some air quality sensors come with a display screen (either LCD or LED) that shows the air quality data. The housing of the sensor is typically constructed from high-strength materials such as ABS or polycarbonate, offering durability and protection against environmental factors, often with an IP65+ rating for water and dust resistance. The sensor’s power supply unit generally operates on 5V, 12V, or 24V DC, depending on the application and the output requirements. Additionally, some models feature three-color LED indicators to provide visual alarms, as well as alarm relay outputs that can trigger external devices such as ventilation fans or sirens to respond to air quality changes.

Main Types of Air Quality Sensors

Air quality sensors are categorized based on what they detect and how they’re used:

By Pollutant Type:

• CO₂ Sensors: Detect carbon dioxide levels, crucial for HVAC systems and indoor air quality control.
• TVOC Sensors: Measure volatile organic compounds emitted from paint, furniture, solvents, and cleaning products.
• Formaldehyde (CH₂O) Sensors: Target this hazardous compound often found in new construction and furnishings.
• PM Sensors (PM1.0, PM2.5, PM10): Detect fine dust, smoke, and combustion-related particles.
• Ozone (O₃), NOx, and SO₂ Sensors: Monitor outdoor pollutants from vehicles, industry, or ozone generators.

By Physical Structure:

• Wall-mounted Sensors: Installed in fixed positions in buildings or industrial environments.
• Ceiling-mounted Sensors: Often used in HVAC systems and smart ceilings.
• Portable Air Quality Monitors: Handheld or wearable devices for personal or field use.
• Smart Sensors with IoT Support: Communicate via Wi-Fi, Zigbee, or LoRa for remote access and integration with smart systems.

Air Quality Sensor Applications

• Indoor Air Quality Monitoring: Homes, offices, hospitals, and schools use air quality sensors to maintain healthy indoor environments. These sensors detect harmful gases released by materials, poor ventilation, or indoor activities, and trigger air purifiers or fresh air systems.
• Industrial Safety and Compliance: Factories and laboratories use air sensors to detect toxic emissions, gas leaks, and particulate pollution. In hazardous environments like chemical processing plants, real-time monitoring ensures worker safety and regulatory compliance.
• Building Automation and HVAC: Sensors are key to smart building management, where they feed data into BMS systems to optimize airflow, reduce energy use, and maintain comfort levels. Demand-controlled ventilation systems rely heavily on CO₂ and VOC sensors.
• Smart Cities and Environmental Monitoring: Deployed on street poles, rooftops, and transport systems, outdoor air quality sensors track pollution trends, inform citizens via apps, and guide urban planning and regulatory actions.
• Agricultural and Greenhouse Monitoring: In greenhouses or animal barns, air pollution sensors monitor CO₂ levels, ammonia, and humidity to ensure optimal conditions for growth and animal welfare.
• Automotive and Public Transport: Modern vehicles use air quality sensors inside the cabin to adjust ventilation, recirculate air, or trigger alerts when pollutants exceed thresholds. Public transport systems use them in stations and tunnels for ventilation control.

Benefits of SUCH Air Quality Sensors

• Real-time Monitoring: Continuous 24/7 data collection ensures timely responses to pollution spikes.
• High Precision and Sensitivity: Modern sensors offer precise measurements with minimal interference.
• Wide Detection Range: From 0–1000 μg/m³ for PM and 0–5000 ppm for gases.
• Multi-parameter Measurement: Many air purity sensors combine gas, particle, temperature, and humidity data in one module.
• Versatile Output Signals: Compatible with various control and monitoring systems.
• Compact Design: Easy to install even in constrained environments.