From clean air to a toxic chamber: Indian cities with the lowest and highest AQI levels, as per CBCP's new report

India’s air on 15 December 2025 told two very different stories. In some corners of the country, the sky was clear and the Air Quality Index sat comfortably in the “good” range. In others, especially around Delhi and the Indo‑Gangetic belt, the air was thick with fine particles, pushing into “very poor” and even “severe” territory according to the Central Pollution Control Board’s (CPCB) official 4 pm bulletin for that day.

CPCB’s daily AQI bulletin for 15 December 2025 at 4 pm pooled 24‑hour data from hundreds of monitoring stations across India. Each station’s Air Quality Index was calculated based on key pollutants such as PM2.5, PM10, nitrogen dioxide, ozone and others, then classified into standard bands: “good” (0–50), “satisfactory” (51–100), “moderate” (101–200), “poor” (201–300), “very poor” (301–400) and “severe” (401–500).

This single snapshot shows how uneven India’s winter air can be. Some locations reported AQI values that pose minimal health concern, while others recorded levels high enough to trigger warnings for vulnerable groups and, in the worst cases, potential emergency measures.

On 15 December, only a limited number of cities and stations made it into the “good” AQI band, with values below 50, meaning pollution levels were considered safe for almost everyone. Among the best performers listed in the bulletin were:

Aizawl, Mizoram: This hill city often fares well in national comparisons, and on 15 December its AQI stayed in the “good” category, signalling low levels of fine particulate matter and other pollutants.

Chamarajanagar, Karnataka: Situated away from heavy industry and dense traffic corridors, it also reported “good” air quality, reflecting the cleaner background levels seen in parts of southern India.

Several other smaller towns, particularly in the South and Northeast, registered AQI in the “good” or “satisfactory” range. In practical terms, this meant that people could exercise outdoors, send children to play outside and go about daily life without significant additional health risks from the air alone, according to CPCB’s own health messaging.

At the other extreme, the 15 December bulletin showed a cluster of locations with AQI values in the “very poor” to “severe” bands. These were concentrated largely in:

Delhi NCR: Several monitoring stations in and around the capital recorded AQI close to or above 400, brushing into the “severe” category. Fine particulate matter (PM2.5) was the dominant pollutant, reflecting the combined impact of traffic, industry, winter inversion layers and regional pollution drifting into the city.

Neighbouring towns in Uttar Pradesh and Haryana: Cities around Delhi, such as those in the wider NCR belt, also fell into “very poor” territory, with AQI values above 300, again mainly due to high PM2.5 levels.

In CPCB’s health framework, “very poor” air can cause respiratory discomfort and aggravate heart and lung disease, especially in older adults, children and those with existing conditions, while “severe” air can trigger more serious health effects, including a higher likelihood of hospital admissions and acute events with prolonged exposure. On a day like 15 December, residents in these worst hit areas were advised to limit outdoor exertion, especially during peak traffic hours, and for sensitive groups to stay indoors as much as possible.

Beyond the numbers, the 15 December data shows why AQI is more than a technical index. For people living in the cleanest cities, it highlights the value of preserving low pollution through careful urban planning, transport policies and protection of green cover. For those in the hardest hit pockets of Delhi NCR and neighbouring states, it is a clear signal that the air on that particular day carried real health risks, especially for children, older adults, pregnant women and anyone with asthma, COPD or heart disease.