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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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Don’t just practise – reverse-engineer the question. This panel shows where this PYQ came from (books / web), how the examiner broke it into hidden statements, and which nearby micro-concepts you were supposed to learn from it. Treat it like an autopsy of the question: what might have triggered it, which exact lines in the book matter, and what linked ideas you should carry forward to future questions.
Q. In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality…
At a glance
Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10

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.
Statement 2
In Indian cities, is carbon monoxide 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?
  • Explicitly lists CO among the eight pollutants that AQI considers in India (PM10, PM2.5, NO2, SO2, CO, O3, NH3, Pb).
  • Named as part of the National Air Quality Index framework described for India.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > b) Urban > p. 66
Presence: 3/5
“(b) Urban . In urban areas, exposure to indoor air pollution has increased due to a variety of reasons, such as dk sr{ANKAri ,", r. -, ,\/ • r construction of more tightly sealed buildings, • r reduced ventilation, • . the use of synthetic materials for building and furnishing and• . the use of chemical products, pesticides, and household care products. • r Indoor air pollution can begin within the building or drawn in from outdoors. • r Other than nitrogen dioxide, carbon monoxide, and lead, there are a number of other poliutants that affect the air quality.”
Why this source?
  • Specifically names carbon monoxide as a pollutant that affects urban air quality.
  • Links CO to urban/indoor air pollution context, supporting its relevance to city-level air quality assessment.
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?
  • Identifies carbon monoxide as one of the major gaseous pollutants in air.
  • Notes the AQI as the tool used to describe air quality, connecting pollutants to AQI usage.
Statement 3
In Indian cities, is nitrogen 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?
  • Explicitly states the National AQI considers eight pollutants and lists NO2 (rendered as NOz/NOx) among them.
  • Gives the AQI framework used in India, directly linking NO2 to AQI calculation.
Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > A step further > p. 119
Presence: 4/5
“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?
  • Identifies nitrogen dioxide as a major air pollutant in the air.
  • Notes AQI is the tool used to describe air quality, implying inclusion of major pollutants like NO2.
Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 17: Contemporary Issues > 1. Air Pollution > p. 38
Presence: 3/5
“The presence in the Earth's atmosphere of man-caused or manmade contaminants which may adversely affect property, or the lives of plants, animals, or humans. Commonly air pollution include carbon dioxide, carbon monoxide, lead, nitrogen oxide, ozone, smoke, and sulphur dioxide. The tremendous increase of vehicles during the last three decades in the country has increased the air pollution, especially in the large cities. Consequently, the urban population is suffering more by cough, nausea, irritation of eyes, and various bronchial and visibility problems. Because of the emission of carbon-dioxide, carbon monoxide, nitrogen oxide, and suspended particles of lead and heavy metals, the urban environment is more polluted than the rural environment.”
Why this source?
  • Lists nitrogen oxide as a common urban pollutant caused by vehicles in cities.
  • Supports the relevance of NO2 as a pollutant that AQI would track in urban India.
Statement 4
In Indian cities, is sulfur 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?
  • Directly lists the eight pollutants considered by the National AQI and includes SO2 (sulfur dioxide) among them.
  • Specifies the AQI framework used in India, tying pollutant inclusion to official standards and averaging periods.
Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > A step further > p. 119
Presence: 4/5
“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?
  • Identifies sulfur dioxide as one of the major gaseous air pollutants found in the air.
  • Mentions the AQI as the tool used to describe air quality, linking pollutant relevance to AQI assessment.
Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 17: Contemporary Issues > 1. Air Pollution > p. 38
Presence: 3/5
“The presence in the Earth's atmosphere of man-caused or manmade contaminants which may adversely affect property, or the lives of plants, animals, or humans. Commonly air pollution include carbon dioxide, carbon monoxide, lead, nitrogen oxide, ozone, smoke, and sulphur dioxide. The tremendous increase of vehicles during the last three decades in the country has increased the air pollution, especially in the large cities. Consequently, the urban population is suffering more by cough, nausea, irritation of eyes, and various bronchial and visibility problems. Because of the emission of carbon-dioxide, carbon monoxide, nitrogen oxide, and suspended particles of lead and heavy metals, the urban environment is more polluted than the rural environment.”
Why this source?
  • Names sulphur dioxide among common urban air pollutants in India, supporting its relevance for urban air-quality metrics.
  • Provides context on urban pollution sources and health effects, reinforcing why SO2 would be monitored.
Statement 5
In Indian cities, is methane 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?
  • Snippet explicitly lists the eight pollutants used by the National AQI (PM10, PM2.5, NO2, SO2, CO, O3, NH3, Pb).
  • Methane (CH4) is not included in that enumerated list, implying it is not normally considered in AQI calculations.
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?
  • NCERT lists major gaseous pollutants used in air-quality contexts (CO, O3, NO2, SO2) and particulate matter, without mentioning methane.
  • This corroborates that typical AQI-relevant pollutants discussed in classroom/official descriptions do not include methane.
Pattern takeaway: UPSC consistently sets traps by mixing Global Warming gases (CO2, CH4) with Public Health pollutants. Whenever you study an environmental protocol or index, explicitly note what is EXCLUDED to avoid these 'odd-one-out' traps.
How you should have studied
  1. [THE VERDICT]: Sitter. Direct lift from Shankar IAS (Chapter 5) or any basic current affairs note on the 'Swachh Bharat'/'AQI Launch' (2015).
  2. [THE CONCEPTUAL TRIGGER]: The launch of the National Air Quality Index (NAQI) by the PM in 2015. When a new index arrives, memorize its parameters, not just the launch date.
  3. [THE HORIZONTAL EXPANSION]: Memorize the 'AQI 8': PM10, PM2.5, NO2, SO2, CO, O3, NH3, Pb. Contrast this with the 'NAAQS 12' (National Ambient Air Quality Standards) which adds Benzene, Benzo(a)Pyrene, Arsenic, and Nickel.
  4. [THE STRATEGIC METACOGNITION]: Categorization is key. Create three mental buckets: 1. Greenhouse Gases (Kyoto basket), 2. Ozone Depleting Substances (Montreal basket), 3. Ambient Air Pollutants (AQI basket). Never mix them.
Concept hooks from this question
📌 Adjacent topic to master
S1
👉 Components of India's National AQI (the 8 pollutants)
💡 The insight

Reference [1] explicitly lists the eight pollutants used in calculating the National AQI, which directly answers whether CO2 is included.

High-yield for UPSC environment questions: knowing the specific pollutants used in India's AQI helps answer policy and monitoring questions, connect to health impact discussions, and distinguish local air-quality metrics from greenhouse‑gas metrics. Master by memorizing the pollutant list and practicing application to case questions about monitoring and indices.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > c) National Air Quality Index > p. 70
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > A step further > p. 119
🔗 Anchor: "In Indian cities, is carbon dioxide normally considered in calculating the Air Q..."
📌 Adjacent topic to master
S1
👉 Distinguishing CO (carbon monoxide) vs CO2 (carbon dioxide) in air‑quality context
💡 The insight

Several references mention CO (carbon monoxide) among AQI/urban pollutants while CO2 is discussed separately as a greenhouse gas, highlighting different monitoring and health relevance.

Important for UPSC to avoid conflating local air‑pollution indicators with climate gases. Questions often probe monitoring priorities, health impacts, and policy instruments; understanding which gases affect AQI vs climate (and why) aids clear answers. Study by comparing health effects, monitoring methods, and policy responses for each gas.

📚 Reading List :
  • Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 17: Contemporary Issues > 1. Air Pollution > p. 38
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > carBon dEBt. > p. 54
🔗 Anchor: "In Indian cities, is carbon dioxide normally considered in calculating the Air Q..."
📌 Adjacent topic to master
S1
👉 National Air Quality Monitoring Programme (NAMP) & CPCB role
💡 The insight

Reference [3] describes NAMP objectives and implementation by CPCB, which underpins how AQI data are gathered and used in India.

Knowing institutional frameworks (CPCB, NAMP) is crucial for UPSC: connects technical indices to governance, compliance, and city-level action plans. Useful for questions on implementation, data interpretation, and policy measures. Prepare by reviewing CPCB programmes, monitoring networks, and objectives.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) National Air Quality Monitoring Programme > p. 69
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > c) National Air Quality Index > p. 70
🔗 Anchor: "In Indian cities, is carbon dioxide normally considered in calculating the Air Q..."
📌 Adjacent topic to master
S2
👉 Pollutant list used in India's AQI
💡 The insight

Reference [1] explicitly enumerates the eight pollutants (including CO) that the National AQI uses.

High-yield for UPSC environment questions — knowing which pollutants the AQI tracks (PM10, PM2.5, NO2, SO2, CO, O3, NH3, Pb) helps answer policy, monitoring and health-impact questions. Connects to topics on air quality standards and mitigation measures; revise official frameworks and practice matching pollutants to indices.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > c) National Air Quality Index > p. 70
🔗 Anchor: "In Indian cities, is carbon monoxide normally considered in calculating the Air ..."
📌 Adjacent topic to master
S2
👉 Common urban air pollutants and their relevance
💡 The insight

References [2], [5], and [7] list CO among major urban pollutants and link them to health/urban impact.

Useful across GS papers and essay questions — mastering common urban pollutants (CO, PM, NOx, SO2, O3, Pb) aids answers on urban health, transport policy, and emission controls. Prepare by grouping pollutants by source, health effects, and monitoring approaches.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > A step further > p. 119
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > b) Urban > p. 66
🔗 Anchor: "In Indian cities, is carbon monoxide normally considered in calculating the Air ..."
📌 Adjacent topic to master
S2
👉 CPCB & National Air Quality Monitoring Programme (NAMP)
💡 The insight

Reference [3] names the CPCB-run NAMP which underpins ambient air quality monitoring used for AQI and related assessments.

Important for centre-state governance and institutional questions in UPSC — knowing CPCB's role and NAMP objectives helps answer questions on monitoring, compliance, and non-attainment city identification. Study institutional mandates, monitoring networks, and link to AQI data sources.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) National Air Quality Monitoring Programme > p. 69
🔗 Anchor: "In Indian cities, is carbon monoxide normally considered in calculating the Air ..."
📌 Adjacent topic to master
S3
👉 Pollutants included in the National AQI
💡 The insight

Reference [1] explicitly lists the eight pollutants used by India's AQI, directly addressing whether NO2 is considered.

High-yield for environment syllabus: knowing which pollutants constitute the AQI helps answer questions on air-quality policy and health advisories. It connects to topics on NAAQS, health impacts, and urban pollution control; learn by memorising the standard pollutant list and practising application-based MCQs.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > c) National Air Quality Index > p. 70
🔗 Anchor: "In Indian cities, is nitrogen dioxide normally considered in calculating the Air..."
🌑 The Hidden Trap

The 'NAAQS 12' vs 'AQI 8' gap. The 4 pollutants monitored in NAAQS but NOT used for the daily AQI calculation are Benzene, Benzo(a)Pyrene, Arsenic, and Nickel. A future question will likely ask: 'Which of these is monitored under NAAQS but not part of the daily AQI?'

⚡ Elimination Cheat Code

Use the 'Toxicity Logic'. AQI measures immediate threat to life/lungs. We exhale CO2 constantly; it is not toxic at city concentrations (it's a climate warmer, not a lung poison). Therefore, CO2 cannot be a parameter for a 'Health Index'. Eliminate Option 1 (CO2) -> A, C, and D are removed instantly. Answer is B.

🔗 Mains Connection

Link to Mains GS-2 (Health) and GS-3 (Environment): The AQI categories (Good to Severe) trigger the 'Graded Response Action Plan' (GRAP) in Delhi-NCR. Mentioning GRAP stages (e.g., halting construction at 'Severe') adds policy depth to your pollution answers.

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SIMILAR QUESTIONS

CDS-I · 2013 · Q1 Relevance score: -1.42

Which one among the following has been included as a parameter for the first time under the National Ambient Air Quality Standards (NAAQS), based on Central Pollution Control Board and IIT, Kanpur research, WHO guidelines and European Union limits and practices ?

CDS-II · 2017 · Q120 Relevance score: -1.82

Which on^ of the following is not included in the National Air Quality Index? a

CDS-I · 2018 · Q41 Relevance score: -2.89

Consider the following constituent gases of the atmosphere : 1. Argon 2. Neon 3. Helium 4. Carbon dioxide Which one of the following is the correct descending sequence of the above gases in terms of the volume percentage?

CDS-I · 2009 · Q109 Relevance score: -4.13

Which one of the following is associated with the formation of brown air in traffic congested cities ?

NDA-II · 2017 · Q67 Relevance score: -4.19

Which one of the following gases is placed second in respect of abundance in the Earth’s atmosphere ?