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Q86 (IAS/2016) Environment & Ecology › Pollution & Conservation › Air quality standards Official Key

In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index? 1. Carbon dioxide 2. Carbon monoxide 3. Nitrogen dioxide 4. Sulfur dioxide 5. Methane Select the correct answer using the code given below.

Result
Your answer: —  ·  Correct: B
Explanation

The correct answer is option B (2, 3, and 4 only) because the National Air Quality Index (AQI) considers eight pollutants: PM10, PM 2.5, NO2, SO2, CO, O3, NH3, and Pb[2]. This clearly shows that carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide (SO2) are considered in the AQI calculation, which corresponds to statements 2, 3, and 4.

Notably, carbon dioxide (CO2) and methane (CH4) are **not** included in the list of pollutants monitored by India's National AQI, despite being important greenhouse gases. The National Air Quality Index was launched by the Prime Minister in April 2015 starting with four cities to disseminate air quality information[1], and it focuses on pollutants with direct health impacts rather than general greenhouse gases.

Therefore, only carbon monoxide, nitrogen dioxide, and sulfur dioxide from the given list are actually used in calculating India's Air Quality Index, making option B the correct answer.

Sources
  1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > c) National Air Quality Index > p. 70
  2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > c) National Air Quality Index > p. 70
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Q. In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality…
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Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10
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This is a classic 'Index Composition' question. UPSC loves asking what goes INSIDE a basket (CPI, WPI, IIP, AQI). The trap here is confusing 'Greenhouse Gases' (CO2, Methane) with 'Criteria Air Pollutants' (SO2, NO2, PM). If it's a daily health index, CO2 is rarely included because it isn't toxic at ambient levels.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
In Indian cities, is carbon dioxide normally considered in calculating the Air Quality Index (AQI)?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > c) National Air Quality Index > p. 70
Presence: 5/5
“(c) National Air Quality Index . National Air Quality index 'aras launched by the Prime Minister in April, 2015 starting with four cities to disseminate air quality information. The AQI has six categories of air quality, viz Good, Satisfactory, Moderately Polluted, Poor, Very Poor and Severe. Each of these categories is associated with likely health impacts. AQI considers eight pollutants (PMro, PM 2.S, NOz, SOz, CO, O3, NH3 and Pb) for which (up to z4-hourly averaging period) National Ambient Air Quality Standards are prescribed.”
Why this source?
  • Explicit list of pollutants used for the National AQI in India is given and CO2 is not among the eight listed (PM10, PM2.5, NO2, SO2, CO, O3, NH3, Pb).
  • This snippet comes from a source describing the National Air Quality Index methodology, directly relevant to AQI calculations in India.
Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > A step further > p. 119
Presence: 3/5
“The major pollutants present in the air are particulate matter (dust, soot) and gases like carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide. The air quality index (AQI) is a tool used to describe the air quality. (a) with no dust particles; (b) with dust particles Fig. 8.5: Lime water turns milky in the presence of carbon dioxide”
Why this source?
  • Describes major air pollutants and lists common gases (CO, O3, NO2, SO2) associated with AQI-type monitoring but does not include CO2.
  • Supports the notion that commonly monitored urban air-quality gases are those other than CO2.
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