SmogRank / India / West Bengal / Kolkata
Kolkata, month by month
Kolkata has a measured daily mean on 1,174 days since 7 May 2023. Its worst month was January 2024, at 261 US AQI (185.9 µg/m³), 5th of 2,385 cities on that month's world ranking. Its cleanest was July 2023, at 58 US AQI (12.8 µg/m³). 2025 averaged 152 US AQI (57.5 µg/m³), against 163 US AQI (72.4 µg/m³) in 2024.
Every month since 2023
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Months without a mean, and why
2 months
| Month | Why |
|---|---|
| Oct 2026 | 6 of 12 days measured; a month needs 9. The others: 5 with no readings from the monitors, 1 with readings for part of the day (a day needs 18 hours). |
| Jan 2026 | 21 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Kolkata's worst months
| Month | US AQI | World rank |
|---|---|---|
| January 2024 | 261185.9 µg/m³ | 5thof 2,385 |
| January 2025 | 248173.4 µg/m³ | 3rdof 2,474 |
| December 2024 | 227152.1 µg/m³ | 5thof 2,616 |
| December 2023 | 227151.7 µg/m³ | 5thof 2,247 |
| November 2024 | 204128.4 µg/m³ | 4thof 2,624 |
| November 2023 | 204128.1 µg/m³ | 4thof 2,243 |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Kolkata's worst days
| Day | US AQI |
|---|---|
| 25 Dec 2023 | 396273.0 µg/m³ |
| 26 Nov 2024 | 362256.0 µg/m³ |
| 14 Jan 2024 | 350250.0 µg/m³ |
| 21 Jan 2024 | 348249.0 µg/m³ |
| 25 Nov 2024 | 340245.0 µg/m³ |
| 12 Jan 2025 | 322236.0 µg/m³ |
| 11 Jan 2025 | 314232.0 µg/m³ |
| 23 Jan 2024 | 312231.0 µg/m³ |
| 15 Dec 2023 | 310230.0 µg/m³ |
| 14 Jan 2025 | 304227.0 µg/m³ |
Daily means, the highest since 7 May 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Kolkata, India, 7 May 2023 – 7 Oct 2026. Monitor data from CPCB via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/in/kolkata/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Kolkata now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 20:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).