What is Air Quality Index (AQI)?
The air quality in any city is determined by the Air Quality Index (AQI). This indicator is developed by government agencies. To assess a city's AQI, various pollutants are considered. During the evaluation, the concentration of these pollutants in the air is measured. The AQI levels help inform people about whether air pollution is increasing or decreasing. Additionally, it is explained how air pollution can be harmful to people's health and in what ways. When the AQI rises, people are advised to take precautions, such as wearing masks outdoors and using air purifiers indoors.
Most Polluted City/States in India
Updated: December 13, 2025| Rank | City, States | AQI |
|---|---|---|
| 1 | Muzaffarnagar, Uttar Pradesh | 400 |
| 2 | Noida, Uttar Pradesh | 386 |
| 3 | Meerut, Uttar Pradesh | 384 |
| 4 | Baghpat, Uttar Pradesh | 383 |
| 5 | Greater Noida, Uttar Pradesh | 373 |
| 6 | Mandideep, Madhya Pradesh | 370 |
| 7 | Ghaziabad, Uttar Pradesh | 363 |
| 8 | Ballabgarh, Haryana | 359 |
| 9 | Delhi, Delhi | 349 |
| 10 | Kaithal, Haryana | 324 |
Frequently Asked Questions
What is a good AQI level?
A good AQI level is between 0 and 50, indicating air quality that poses little or no risk to health.
What is the safe range of AQI?
The safe range of AQI is from 0 to 100, covering the categories of "Good" (0-50) and "Moderate" (51-100).
What are the criteria for AQI?
AQI criteria include measuring the concentration of pollutants like PM2.5, PM10, ozone, nitrogen dioxide, sulphur dioxide, carbon monoxide, and ammonia over a specified averaging period.
What are the 8 parameters of AQI?
The 8 parameters of AQI are: Particulate Matter (PM10), Particulate Matter (PM2.5), Ozone (O3), Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2), Carbon Monoxide (CO), Ammonia (NH3), and Lead (Pb).
How is AQI calculated?
AQI is calculated using pollutant concentration data, which is converted into an AQI value for each pollutant through specific formulae. The highest value among these is reported as the overall AQI for the location.
What are the 6 categories of AQI?
The 6 categories of AQI are: 0-50: Good 51-100: Moderate 101-200: Poor 201-300: Unhealthy 301-400: Severe 401-500+: Hazardous