Estimated reading time: 4 minutes
Table of contents
Why is Air Quality Index in the News?
Delhi’s AQI is currently around 159, marking unhealthy air conditions dominated by high PM2.5 (68 µg/m³) and PM10 (165 µg/m³) levels. Meteorologists have warned that stagnant wind speeds below 10 km/h are reducing pollutant dispersion, worsening the situation in northern India.
Meanwhile, Mumbai’s air quality remains “Moderate” with an AQI of 135, though some areas like Kalamboli have slipped into the “Poor” category at 201, attributed to post-monsoon atmospheric changes and rising vehicular emissions. The Central Pollution Control Board (CPCB) has reported similar moderate air quality levels across cities such as Jaipur (174), Meerut (181), and Jodhpur (125). Environmental experts caution that with the onset of the winter season and upcoming Diwali festivities, pollution levels may spike further in the coming week
Why Air Quality Index Matters?
Have you ever wondered what those “AQI numbers” shown on your weather app actually mean?
The Air Quality Index (AQI) is a scientific tool that indicates how polluted or clean the air around us is. It plays a crucial role in environmental management, health policy, and urban planning, helping people and governments take timely action.
In simple terms, AQI converts complex air pollutant data into a single number and color code that everyone can understand.
What Is Air Quality Index (AQI)?
The Air Quality Index is an indicator that measures and categorizes air pollution levels in a specific region. It is calculated based on the concentration of major air pollutants such as:
- PM10 (Particulate Matter ≤10 µm)
- PM2.5 (Particulate Matter ≤2.5 µm)
- NO₂ (Nitrogen Dioxide)
- SO₂ (Sulphur Dioxide)
- CO (Carbon Monoxide)
- O₃ (Ozone)
- NH₃ (Ammonia)
- Pb (Lead)
Each pollutant is given a sub-index, and the highest sub-index among them becomes the overall AQI.
How Is AQI Calculated in India?
India’s National Air Quality Index (NAQI) was launched in 2014 by the Ministry of Environment, Forest and Climate Change (MoEFCC) under the Swachh Bharat Mission.
The Central Pollution Control Board (CPCB) manages it across 400+ cities.
| AQI Range | Category | Color Code | Health Impact |
| 0–50 | Good | Green | Minimal impact |
| 51–100 | Satisfactory | Light Green | Minor breathing discomfort |
| 101–200 | Moderate | Yellow | Discomfort to sensitive people |
| 201–300 | Poor | Orange | Breathing issues for all |
| 301–400 | Very Poor | Red | Respiratory illness on prolonged exposure |
| 401–500 | Severe | Maroon | Serious health effects even on healthy people |
Note: CPCB monitors AQI in real-time using Continuous Ambient Air Quality Monitoring Stations (CAAQMS).
Geographical Aspects of Air Pollution in India
The Indo-Gangetic Plains (covering Punjab, Haryana, Delhi, Uttar Pradesh, and Bihar) consistently show high AQI values, especially in winter months due to:
- Stubble burning,
- Temperature inversion,
- Vehicular and industrial emissions,
- Low wind speed and topographical trapping of pollutants.
In contrast, coastal cities like Chennai or Mumbai often record better AQI levels because sea breeze helps disperse pollutants.
Government Initiatives to Improve Air Quality
- National Clean Air Programme (NCAP) – launched in 2019, aims to reduce PM2.5 and PM10 levels by 20–30% by 2024–25.
- Commission for Air Quality Management (CAQM) – monitors NCR and adjoining states.
- Graded Response Action Plan (GRAP) – enforces emergency measures like ban on construction and firecrackers.
- BS-VI Emission Standards – reduce vehicular pollution significantly.
- Smog Towers and Electric Vehicles (EVs) – introduced as part of long-term urban pollution control.
Important Facts for Exams
- India’s first AQI system was launched in Delhi, 2014.
- PM2.5 is the most harmful pollutant for human lungs.
- CPCB is the nodal agency for AQI implementation.
- Data sources include IMD, ISRO, and Urban Local Bodies.
- Winter inversion and low boundary layer height trap pollutants
Sources: CPCB
Frequently Asked Questions (FAQs)
Q1. What is the full form of AQI?
Answer: AQI stands for Air Quality Index, which indicates the pollution level in the atmosphere.
Q2. Which organization releases AQI data in India?
Answer: The Central Pollution Control Board (CPCB) under the MoEFCC.
Q3. What is the acceptable level of AQI for healthy living?
Answer: AQI between 0–100 is considered Good to Satisfactory.
Q4. Why is AQI higher in winter?
Answer: Due to temperature inversion, low wind speed, and increased biomass burning.
Q5. Which cities in India record the worst AQI?
Answer: Delhi, Ghaziabad, Faridabad, and Lucknow are among the most polluted cities.
