Question

Consider the following statements:

P: According to the National Ambient Air Quality Standards (Central Pollution Control Board, Govt. of India, notification 2009), annual time-weighted average \( \text{PM}_{10} \) standard is more than \( \text{PM}_{2.5} \) standard.

Q: According to the National Air Quality Index released by Govt. of India in 2015, sub-index value of \( \text{PM}_{10} \) can be less than that of \( \text{PM}_{2.5} \).

Choose the correct option from the following:

• A. P is TRUE; Q is FALSE
• B. P is FALSE; Q is TRUE
• C. P is TRUE; Q is TRUE
• D. P is FALSE; Q is FALSE

Hint:

\( \text{PM}_{10} \) refers to particles with diameter ≤ 10 µm; \( \text{PM}_{2.5} \) refers to finer particles ≤ 2.5 µm. \( \text{PM}_{2.5} \) is more harmful due to deeper penetration into lungs, hence its stricter standards. AQI sub-index values vary with pollutant concentration ranges, and may differ even for related pollutants.

Answer 1

The Correct Option is C

Step 1: Analyze Statement P.
According to the National Ambient Air Quality Standards (NAAQS), notified by the Central Pollution Control Board (CPCB) in 2009:
Annual average standard for \( \text{PM}_{10} = 60 \, \mu g/m^3 \)
Annual average standard for \( \text{PM}_{2.5} = 40 \, \mu g/m^3 \)
\[ \text{Since } 60 > 40, \quad \text{P is TRUE.} \] Step 2: Analyze Statement Q.
The National Air Quality Index (AQI) released in 2015 uses sub-indices for pollutants including \( \text{PM}_{10} \) and \( \text{PM}_{2.5} \).
Sub-index values are calculated based on concentration ranges. It is possible for \( \text{PM}_{10} \) levels to fall in a lower AQI category (e.g., 'Moderate'), while \( \text{PM}_{2.5} \) levels fall in a higher one (e.g., 'Poor'), based on their respective concentration thresholds. \[ \text{Hence, it is possible that the sub-index of PM}_{10} \text{ is less than that of PM}_{2.5}. \Rightarrow \text{Q is TRUE.} \] Final Conclusion:
Both statements P and Q are TRUE.