Question

What are the different techniques of monitoring air quality of a place? Discuss briefly any two of the methods.

Hint:

For exams, mention the \textbf{Air Quality Index (AQI)}, which is the standard numerical value calculated based on these monitoring techniques to communicate air health to the public.

Answer 1

Step 1: Understanding the Concept:
Air quality monitoring involves the systematic measurement of pollutants like $PM_{2.5}$, $PM_{10}$, $SO_x$, $NO_x$, and $O_3$ to assess environmental health and compliance with standards.

Step 2 : Detailed Explanation:

Techniques of Monitoring:
- Passive Sampling (using diffusive samplers).
- Active Sampling (pumping air through a filter/medium).
- Continuous Real-time Monitoring (using automated sensors).
- Remote Sensing (using satellites or LIDAR).

Discussion of Two Methods:
1.
Continuous Online Monitoring: This method uses automated electronic sensors to provide real-time data on pollutant concentrations. It is highly accurate and allows for immediate public health warnings (e.g., AQI updates).
2.
Passive Sampling: This involves using simple tubes or badges that absorb pollutants from the air via natural diffusion. While they don't provide real-time data, they are low-cost, don't require power, and are excellent for identifying long-term trends over wide areas.

Step 3: Final Answer:
Air monitoring is done through various physical and electronic means, with Continuous Monitoring being the most precise for real-time analysis, and Passive Sampling being a cost-effective alternative for long-term study.