Methodology: How DailyAQI Computes the Index

DailyAQI is built for transparency and accuracy. Here is exactly how the numbers on this site are produced.

Data source

Pollutant measurements come from Central Pollution Control Board (CPCB) continuous monitoring stations, published through the Government of India's open-data portal (data.gov.in) under the Government Open Data License – India. Each city may have several stations; we use the most representative recent readings.

How the AQI is calculated

For each pollutant we take the reported 24-hour concentration and convert it to a sub-index using the CPCB breakpoint table (for PM2.5, PM10, NO₂, O₃, SO₂ and NH₃). The overall city AQI is the maximum of these sub-indices, and the pollutant responsible is labelled the dominant pollutant — this is the official Indian method. In practice, India's AQI is almost always driven by particulate matter (PM2.5 or PM10).

We currently exclude carbon monoxide (CO) from the calculation: the open-data feed reports CO in units that do not match the CPCB mg/m³ breakpoints, and rather than publish a figure we cannot verify, we omit it. Because CO effectively never determines the Indian AQI, this keeps our headline number aligned with CPCB's published values.

Our integrity rule

We never invent or estimate a reading. If a city has no fresh station data, the page clearly says "data updating" instead of showing a number. Timestamps and station counts are shown so you can judge how current a reading is.

Limitations

Readings are indicative and can lag the source or vary between nearby stations. For medical decisions or official action, always consult CPCB and local health advisories directly.