“Every November, the city wakes to a haze that won't lift until February. In summer, Nor'westers scrub the sky clean in twenty minutes.”
Kolkata Air Quality & AQI History
Kolkata air quality analysis
Kolkata's air is not uniformly bad — it is seasonally catastrophic. Across some 1,500 days of readings, the median AQI in January is 291. In July it is 28. That is a tenfold swing inside a single calendar year, driven almost entirely by winter temperature inversions that cap the city and hold pollution near ground level.
The pattern shows up in the correlation too: temperature and AQI move against each other at about −0.71. Cold days are dirty days. Of the days recorded here, roughly 330 exceeded an AQI of 200, while over 500 sat at 50 or below.
About this data
What this page shows
A daily AQI time series since January 2022, a month-by-month distribution that exposes the winter spike, seasonal averages by year, and a stacked breakdown of the individual pollutants — PM2.5, PM10, NO₂, SO₂, CO and O₃ — behind the headline index. Mean AQI across the whole record sits in the low 120s.
Where the data comes from
Readings come from the Open-Meteo air quality API, which serves the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis for Kolkata. This is a modelled product assimilating satellite and ground observations, not a direct feed from a CPCB monitoring station.
Limitations worth knowing
Because the source is a reanalysis grid rather than a physical monitor, the values describe the city as a whole and will not match any single CPCB station reading on a given day. Treat them as a consistent basis for comparing seasons and years, not as a substitute for regulatory monitoring. Coverage begins in 2022, which is too short a window to establish a long-term pollution trend — four winters is enough to characterise the seasonal cycle and no more. Early rows in the series carry null values where the upstream model had no output.
Embed this page
Drop these charts into your blog, brief, or report. Updates flow through automatically.