UPSC Prelims 2016 Q86: Environment & Ecology – Pollution & Waste Management
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.
- (a) 1, 2 and 3 only
- (b) 2, 3 and 4 only
- (c) 1, 4 and 5 only
- (d) 1, 2, 3, 4 and 5
Answer: (b) 2, 3 and 4 only
Explanation
Air Quality Index (AQI)
India's National Air Quality Index was launched in 2015.
It turns the levels of eight pollutants into one number, one colour.
| Gas in the question | Counted in the Air Quality Index? |
|---|---|
| 1. Carbon dioxide | No |
| 2. Carbon monoxide | Yes |
| 3. Nitrogen dioxide | Yes |
| 4. Sulfur dioxide | Yes |
| 5. Methane | No |
The eight pollutants:
| Type | Pollutants |
|---|---|
| Particles | PM10, PM2.5 |
| Gases | Nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, ammonia |
| Metal | Lead |
The index has six categories, from Good to Severe.
Carbon dioxide and methane are greenhouse gases, not health pollutants in this index.
Answer: (b) 2, 3 and 4 only.
Why each option is right or wrong
- (a) Incorrect. Carbon dioxide is not considered in calculating the Air Quality Index.
- (b) CORRECT. Carbon monoxide, nitrogen dioxide and sulfur dioxide are counted.
- (c) Incorrect. Carbon dioxide and methane are greenhouse gases, not index pollutants.
- (d) Incorrect. The index leaves out carbon dioxide and methane.
Key point
National AQI (2015): eight pollutants - PM10, PM2.5, NO2, SO2, CO, ozone, ammonia, lead; six categories; no carbon dioxide or methane.
Remember
AQI: eight pollutants; no carbon dioxide, no methane.
Common mistakes
- Including carbon dioxide, the best-known gas, in the index.
- Forgetting ammonia and lead, the less obvious pollutants.
- Confusing air quality pollutants with greenhouse gases.
Exam tip
AQI is about health, not climate. Greenhouse gases are out.
Sources
- Central Pollution Control Board — National Air Quality Index
- Press Information Bureau — National Air Quality Index launched (6 April 2015)