AQI Categories: Levels, Colours & Health Effects
India's Air Quality Index uses six categories, each with a colour and a health message defined by the Central Pollution Control Board. The category is decided by the overall AQI value, which itself is the highest pollutant sub-index.
| AQI | Category | Associated health impact |
|---|---|---|
| 0–50 | Good | Air quality is considered satisfactory and air pollution poses little or no risk. |
| 51–100 | Satisfactory | Acceptable air quality; minor breathing discomfort possible for unusually sensitive people. |
| 101–200 | Moderate | May cause breathing discomfort to people with lung disease such as asthma, and to children and older adults. |
| 201–300 | Poor | May cause breathing discomfort to most people on prolonged exposure. |
| 301–400 | Very Poor | May cause respiratory illness on prolonged exposure; effects more pronounced for people with lung and heart disease. |
| 401–500 | Severe | Affects healthy people and seriously impacts those with existing diseases; avoid outdoor activity. |
Who should act, and when
Healthy adults are usually unaffected until the "Poor" range, but sensitive groups — children, older adults, pregnant people and those with asthma, COPD or heart disease — should reduce prolonged or heavy outdoor exertion once the AQI passes 100, and stay indoors as it climbs into the "Very Poor" and "Severe" bands. When the index is high, an N95/FFP2 mask outdoors and an indoor air purifier meaningfully reduce exposure to fine particles.
Frequently asked questions
What colour is used for severe AQI?
The "Severe" category (401–500) is shown in dark maroon; "Very Poor" (301–400) is red.
What is the highest AQI category?
"Severe" (401–500) is the worst category and indicates air that affects healthy people and seriously harms those with existing illness.