Kolkata, India Air Quality & Smog

Dominant pollutants, when pollution and smog are worst, a notable historical episode, and the official monitoring agencies for Kolkata, India — plus how to check the current reading. Kolkata reports air quality on the National Air Quality Index — our full guide explains how that scale works and how it compares to the US AQI.

Dominant pollutants

PM2.5, PM10.

Seasonal pattern: when smog is worst

Kolkata's winter (November–February) is its problem season: cool, stagnant air traps particulate from vehicles, biomass and coal burning, and pollution transported down the Indo-Gangetic Plain. In bad winters the city ranks among India's most polluted, with "Very Poor" days comparable to Delhi's.

A notable air-quality episode

Recent winters have repeatedly pushed Kolkata into the "Very Poor" and "Severe" AQI bands, with the West Bengal Pollution Control Board issuing advisories during the worst Indo-Gangetic Plain episodes.

The local index and who runs it

Kolkata reports air quality using the National Air Quality Index, not the US AQI — so the same air can read as a different number than you may be used to. The CPCB portal publishes WBPCB's station readings across Kolkata.

• West Bengal Pollution Control Board (WBPCB)
• CPCB

How to check air quality in Kolkata

For the official live reading, the agency portals above are the canonical source. To understand what the numbers mean, start with our guide to the National Air Quality Index and the broader comparison of world air-quality indices. Smog Report puts glanceable air quality on your iPhone — widgets, Live Activities, Siri, and Apple Watch — free and with no account.

Common questions about Kolkata air quality

Why does Kolkata have air-quality and smog problems?

Kolkata's winter (November–February) is its problem season: cool, stagnant air traps particulate from vehicles, biomass and coal burning, and pollution transported down the Indo-Gangetic Plain. In bad winters the city ranks among India's most polluted, with "Very Poor" days comparable to Delhi's.

What are the main air pollutants in Kolkata?

Kolkata's dominant pollutants are PM2.5, PM10. The reading on any given day is usually driven by whichever of these is highest.

Has Kolkata had a major air-quality or smog event?

Recent winters have repeatedly pushed Kolkata into the "Very Poor" and "Severe" AQI bands, with the West Bengal Pollution Control Board issuing advisories during the worst Indo-Gangetic Plain episodes.

What air-quality index does Kolkata use?

Kolkata reports air quality on the National Air Quality Index (AQI), not the US AQI — so the same air can read as a different number than you may be used to. For live, glanceable readings on your iPhone, the free Smog Report app auto-selects the right local index for wherever you are.

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