Air monitors work primarily by using a combination of laser technology and electrochemical methods to measure the concentration of particulate matter and gases in the air. This involves detecting and quantifying pollutants to assess air quality.
Here's a more detailed breakdown:
1. Particulate Matter (PM) Measurement (Laser Technology):
- Laser Scattering: Many air monitors use a laser beam to illuminate airborne particles.
- Light Detection: When particles pass through the laser beam, they scatter the light. A detector measures the amount of scattered light.
- Correlation to Particle Size and Concentration: The intensity of the scattered light is directly related to the size and concentration of the particles. Larger and more numerous particles scatter more light. The monitor uses algorithms to correlate the light scattering data to the concentration of PM2.5 (particulate matter with a diameter of 2.5 micrometers or less) and PM10 (particulate matter with a diameter of 10 micrometers or less). These are common air pollutants.
2. Gas Measurement (Electrochemical Sensors):
- Electrochemical Cells: Air monitors often employ electrochemical sensors to detect specific gases like carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), and sulfur dioxide (SO2).
- Chemical Reaction: These sensors contain electrochemical cells with electrodes and electrolytes. When a target gas comes into contact with the sensor, it undergoes a chemical reaction at the electrode.
- Current Generation: This reaction generates an electrical current that is proportional to the concentration of the gas.
- Signal Processing: The monitor measures this current and converts it into a concentration reading (e.g., parts per million - ppm).
3. Sensor Gas Module and Diode Colors (Simplified Explanation):
The reference mentions a sensor gas module with two cells and diodes. This refers to the electrochemical sensors described above. Each sensor likely contains multiple electrodes within a cell. The color change of the diodes, depending on air quality, likely refers to an indicator light system communicating the current air quality level based on the sensor readings. These diodes act as a visual display, showing the current concentration of pollutants.
In summary, air monitors use laser technology to detect and measure particulate matter, and electrochemical sensors to detect and measure gases, providing a comprehensive assessment of air quality.
