Question

According to the National Ambient Air Quality Standards (CPCB, Govt. of India, 2009), which of the following statement(s) is/are correct?

• A. SO2 and NO2 have annual average standards; while O3 and CO have eight hour average standards.
• B. SO2 and CO have annual average standards; while O3 and NO2 have eight hour average standards.
• C. SO2 and CO have eight hour average standards; while O3 and NO2 have hourly average standards.
• D. SO2 and NO2 have 24 hour average standards; while O3 and CO have hourly average standards.

Hint:

NAAQS standards differ by pollutant: gaseous pollutants like O3 and CO use short-term averages (hourly), while SO2 and NO2 use both 24-hour and annual limits.

Answer 1

The Correct Option is A, D

As per NAAQS 2009:
SO2: annual + 24-hour standards exist → matches (A) and (D).
NO2: annual + 24-hour standards exist → again matches (A) and (D).
O3: only 1-hour and 8-hour standards exist → matches (A).
CO: 1-hour and 8-hour standards exist → matches (A).
Statement (B) is incorrect because CO does not have annual standards.
Statement (C) is incorrect because SO2 and CO do not have 8-hour standards.
Final Answer: (A), (D)