Air quality is monitored to measure the concentration of pollutants in the atmosphere and assess their impact on human health and the environment. Various methods and instruments are used depending on the pollutants being measured.
1. Ground-Based Monitoring
- Air Sampling Stations:
- Collect air samples at fixed locations for laboratory analysis.
- Measures gases (CO, NOx, SO₂), particulate matter, and VOCs.
- Continuous Air Quality Monitors:
- Instruments like Gas Analyzers and Particulate Monitors provide real-time data.
- Examples: Infrared analyzers for CO₂, chemiluminescence analyzers for NOx.
- Particulate Matter (PM) Measurement:
- PM₂.₅ and PM₁₀ are measured using filters, optical sensors, or laser-based instruments.
- Meteorological Sensors:
- Measure wind speed, direction, temperature, and humidity to understand pollutant dispersion.
2. Remote Sensing (Satellite Monitoring)
- Satellites measure global air pollutants like NO₂, SO₂, O₃, CO, and aerosols.
- Examples:
- NASA’s Aura satellite monitors ozone and other gases.
- Sentinel-5P provides data on NO₂, CO, and aerosols.
3. Biological Indicators
- Certain plants, lichens, or mosses are used as bioindicators to detect long-term pollution levels.
4. Data Analysis and Air Quality Index (AQI)
- Collected data is analyzed to calculate the Air Quality Index (AQI).
- AQI provides a simple scale (0–500) indicating whether the air is safe or hazardous.
In short:
Air quality is monitored using ground-based instruments, satellites, and biological indicators, measuring gases, particulate matter, and meteorological conditions to assess pollution levels and protect public health.