Consider the following statements regarding pollution indices and environmental events:

Question

Consider the following statements regarding pollution indices and environmental events:

I. The Air Quality Index (AQI) in India is based on the concentration of multiple pollutants including PM2.5, PM10, NO2, and CO.

II. The Pollutant Standards Index (PSI) is used in India as the primary national air quality index.

III. The Montreal Protocol (1987) is an international agreement aimed at protecting the ozone layer by phasing out ozone depleting substances.

Which of the statements given above is/are correct?

1. A. I and II only
2. B. I and III only (Correct answer)
3. C. II and III only
4. D. I, II and III

Correct Answer

Option B — I and III only

Detailed Solution & Explanation

The correct answer is I and III only.

Key Points

• Statement I is correct. India's National Air Quality Index, launched in 2014, is computed from eight pollutants — $\text{PM}_{2.5}$, $\text{PM}_{10}$, $\text{NO}_2$, $\text{SO}_2$, $\text{CO}$, $\text{O}_3$, $\text{NH}_3$ and $\text{Pb}$ — so the four named in the statement are indeed among them.
• Statement II is incorrect. The Pollutant Standards Index (PSI) is the older United States index, since replaced there by the US AQI. India's national index is the NAQI, not the PSI.
• Statement III is correct. The Montreal Protocol, 1987 protects the ozone layer by phasing out ozone-depleting substances such as CFCs and halons.

Additional Information

• The NAQI reports on a six-category scale: Good (0-50), Satisfactory (51-100), Moderate (101-200), Poor (201-300), Very Poor (301-400) and Severe (401-500).
• The index is deliberately a worst-of measure: the AQI reported for a station is the highest sub-index among the pollutants, so a single bad pollutant sets the headline figure. The tagline used at launch was "One Number, One Colour, One Description".
• A station needs data for a minimum of three pollutants, one of which must be $\text{PM}_{2.5}$ or $\text{PM}_{10}$, before an AQI can be declared.
• Do not confuse the Montreal Protocol's ozone mandate with the Kyoto Protocol's greenhouse-gas mandate — the recurring trap in this topic.