Question

Which of the following is true according to the Central Pollution Control Board (CPCB), Government of India’s notification issued in the year 2009?

• A. 24 hour averaged standard for PM$_{2.5}$ in ambient air is 60 $\mu g/m^3$; 24 hour averaged standard for PM$_{10}$ in ambient air is 100 $\mu g/m^3$
• B. 24 hour averaged standard for PM$_{2.5}$ in indoor air is 60 $\mu g/m^3$; 24 hour averaged standard for PM$_{10}$ in ambient air is 100 $\mu g/m^3$
• C. 24 hour averaged standard for PM$_{2.5}$ in ambient air is 60 $\mu g/m^3$; 24 hour averaged standard for PM$_{10}$ in indoor air is 100 $\mu g/m^3$
• D. 24 hour averaged standard for PM$_{2.5}$ in indoor air is 60 $\mu g/m^3$; 24 hour averaged standard for PM$_{10}$ in indoor air is 100 $\mu g/m^3$

Hint:

Always differentiate between \textbf{ambient air quality standards} (defined by CPCB) and \textbf{indoor air guidelines} (not covered in CPCB 2009 notification).

Answer 1

The Correct Option is A

Step 1: Recall CPCB 2009 notification.
The CPCB (Central Pollution Control Board) under the National Ambient Air Quality Standards (NAAQS) defined the permissible limits.
Step 2: PM$_{2.5$ limit.}
For ambient air: 24-hour standard = 60 $\mu g/m^3$.
Step 3: PM$_{10$ limit.}
For ambient air: 24-hour standard = 100 $\mu g/m^3$.
Step 4: Verify options.
Only (A) correctly states the ambient air values for both PM$_{2.5}$ and PM$_{10}$. The other options incorrectly mention "indoor air," which is not covered in the 2009 CPCB notification. Final Answer: \[ \boxed{\text{(A) 24-hour PM$_{2.5}$ = 60 $\mu g/m^3$, PM$_{10}$ = 100 $\mu g/m^3$ in ambient air}} \]