Seasonal · 6 min read
Kolkata air pollution this winter: Howrah's Ghusuri runs worst as Kali Puja nears
Kolkata air pollution, winter 2026. CPCB put Kolkata in the Moderate band on 14 of 40 days and Howrah on 20. Worst monitors, weekly trend, Kali Puja rules.
By the Good Air team
In this article · 7 sections
Kolkata air pollution has turned for winter 2026. CPCB's daily bulletin put Kolkata's India NAQI in the Moderate band (101 to 200) on 14 of the 40 days from 15 September to 24 October 2026, and Howrah on 20. Neither city has had a Poor day on the bulletin yet. On 24 October Kolkata was at 105 and Howrah at 132 (CPCB, 24 October).
Among the 12 West Bengal Pollution Control Board (WBPCB) monitors we track, Ghusuri in Howrah had the worst air from 1 to 24 October, with a mean daily India NAQI of 136. Rabindra Bharati University in north Kolkata (130) and Jadavpur (125) came next. Kali Puja and Diwali fall on Sunday 8 November 2026; last year Kolkata's AQI doubled over Kali Puja night.
Key findings
- The season turned at the end of September. The mean of all 12 monitors went from 58 in the week of 22 to 28 September to 127 the week after.
- Howrah is worse than Kolkata. Howrah's five monitors averaged 117 in October, Kolkata's seven 102.
- Two Kolkata monitors had Poor days: Rabindra Bharati University (228 on 5 October, 232 on 6 October) and Victoria (203 on 3 October, 212 on 6 October).
- Only Ghusuri was above 100 every day in October. Bidhannagar (82) and Rabindra Sarobar (83) were cleanest.
- Last winter was far worse. Kolkata was Poor (201 to 300) on 34 days from November 2025 to February 2026 in CPCB's bulletin, and Howrah on 46.
Which parts of Kolkata have the worst air?
The table ranks monitors by mean daily NAQI from 1 to 24 October 2026. PM2.5 is the October mean in µg/m³. "Days above 100" counts Moderate-or-worse days from 15 September to 24 October, out of the days each monitor reported fully. On NAQI, 51 to 100 is Satisfactory, 101 to 200 Moderate and 201 to 300 Poor.
| Rank | Monitor | City | 15–30 Sep | 1–24 Oct | PM2.5 Oct | Days above 100 |
|---|---|---|---|---|---|---|
| 1 | Ghusuri | Howrah | 70 | 136 | 68 | 29 of 40 |
| 2 | Rabindra Bharati University | Kolkata | 83 | 130 | 60 | 23 of 38 |
| 3 | Jadavpur | Kolkata | 71 | 125 | 64 | 23 of 40 |
| 4 | Padmapukur | Howrah | 80 | 117 | 58 | 19 of 40 |
| 5 | Dasnagar | Howrah | 76 | 112 | 58 | 23 of 40 |
| 6 | Botanical Garden | Howrah | 75 | 111 | 58 | 20 of 39 |
| 7 | Belur Math | Howrah | 71 | 110 | 56 | 18 of 40 |
| 8 | Victoria | Kolkata | 68 | 108 | 52 | 11 of 40 |
| 9 | Fort William | Kolkata | 76 | 102 | 54 | 19 of 40 |
| 10 | Ballygunge | Kolkata | 62 | 86 | 41 | 8 of 39 |
| 11 | Rabindra Sarobar | Kolkata | 49 | 83 | 33 | 1 of 38 |
| 12 | Bidhannagar | Kolkata | 55 | 82 | 42 | 4 of 40 |
Ranks use unrounded means. All five Howrah monitors sit in the top seven, and every monitor got worse from September to October. Bidhannagar in Salt Lake and Rabindra Sarobar stayed Satisfactory on average.
The ranking holds on PM2.5 alone. On CPCB's 24-hour scale, PM2.5 above 60 µg/m³ is Moderate. Ghusuri's daily PM2.5 was above that on 20 days and Jadavpur's on 18; Ballygunge and Rabindra Sarobar never crossed it.
How has Kolkata's air changed week by week?
Our city figure averages the monitors' daily NAQI. The CPCB columns count days the 4 pm bulletin put the city at 101 or above.
| Week | Kolkata (our monitors) | Kolkata Moderate days (CPCB) | Howrah (our monitors) | Howrah Moderate days (CPCB) |
|---|---|---|---|---|
| 15–21 Sep | 59 | 0 of 7 | 74 | 0 of 7 |
| 22–28 Sep | 56 | 0 of 7 | 62 | 0 of 7 |
| 29 Sep–5 Oct | 127 | 7 of 7 | 128 | 7 of 7 |
| 6–12 Oct | 109 | 5 of 7 | 124 | 6 of 7 |
| 13–19 Oct | 85 | 1 of 7 | 105 | 3 of 7 |
| 20–24 Oct | 92 | 1 of 5 | 113 | 4 of 5 |
The cleanest day was 22 September, when Kolkata's monitors averaged 36, the same as CPCB's bulletin (CPCB, 22 September). On 27 September the Kolkata average jumped from 46 to 89. Howrah peaked at 146 on 3 October and Kolkata at 148 on 6 October.
During Durga Puja, from Saptami on 18 October to Dashami on 21 October 2026 (West Bengal holiday list, notification of 27 November 2025), Kolkata's monitors averaged 83 to 97 a day and Howrah's 106 to 116. On 24 October Kolkata's average was 100 and Howrah's 122.
In the same 40 days of 2025, CPCB put Kolkata at Moderate or worse on 12 days and Howrah on 11, including Kali Puja on 20 October.
How bad does Kolkata's air get in winter?
Much worse. Every CPCB bulletin from November 2025 to February 2026:
| Month | Kolkata mean AQI | Kolkata Poor days | Howrah mean AQI | Howrah Poor or worse days |
|---|---|---|---|---|
| Nov 2025 | 175 | 7 | 177 | 9 |
| Dec 2025 | 202 | 13 | 227 | 23 |
| Jan 2026 | 198 | 13 | 199 | 14 |
| Feb 2026 | 157 | 1 | 155 | 0 |
The worst day was 12 December 2025: Kolkata 291 and Howrah 306, Very Poor (CPCB, 12 December 2025). Why winter is worse:
- Weather. A six-year WBPCB analysis, reported by the Times of India, named lower wind speeds, temperature inversions and more emissions from vehicles and biomass burning. WBPCB chairman Kalyan Rudra said pollution blown in from outside the state often undoes the city's clean-air work in winter (Times of India, reproduced by the University of Chicago's Breathe, 25 August 2025).
- Burning. A Bose Institute study of Kolkata's winters from 2016 to 2023 found biomass and waste burning to be the main source of PM2.5's most toxic parts, with PM2.5 above 70 µg/m³ on nearly 75% of days from October to February. Under the National Clean Air Programme (NCAP), emissions from vehicles, industry and road dust fell, but biomass burning did not (Down To Earth, 5 May 2025).
The WBPCB analysis found winter 2024-25 was Kolkata's cleanest since 2019, with PM2.5 at 73 µg/m³ in December 2024. Last winter's bulletins show that did not hold.
Kali Puja and Diwali 2026: what to expect
Kali Puja falls on Sunday 8 November 2026, with 9 and 10 November as extra state holidays (West Bengal holiday list, notification of 27 November 2025). Diwali is on the same day in the central government's list (DoPT holiday list, reproduced by StaffNews).
Kolkata's 24-hour AQI was 88 in CPCB's bulletin on 20 October 2025, the day of Kali Puja, and 174 the next afternoon. Howrah went from 82 to 205, Poor (CPCB, 20 October 2025; 21 October 2025). Firecracker rules for 2026 are not out yet. As of 25 October 2026 we could not find a 2026 order from WBPCB, Kolkata Police or the Calcutta High Court. These were the rules in 2025:
- Green crackers only, 8 pm to 10 pm. WBPCB chairman Kalyan Rudra said on 13 October 2025 that only green fireworks certified by PESO or NEERI could be burst, for two hours on Kali Puja and Diwali night (PTI via The Week, 13 October 2025).
- Chhath: 6 am to 8 am. Kolkata Police set the same Kali Puja window and 6 am to 8 am for Chhath, and banned sound crackers and sky lanterns, citing Supreme Court and Calcutta High Court directions (Daily World, 17 October 2025).
- Enforcement. Over Kali Puja 2025, Kolkata Police arrested 183 people for bursting banned firecrackers and seized over 850 kg (National Herald, 21 October 2025).
We could not confirm a current decibel limit from WBPCB or the police. Check their notices in early November for the 2026 order. Our Diwali 2026 air quality guide covers how to protect your home on the night.
How our numbers compare with CPCB's bulletin
Close, not identical. On 1 October 2026 CPCB put Kolkata at 112 and our seven-monitor mean was 107 (CPCB, 1 October). The bulletin covers the 24 hours to 4 pm; our days run 5:30 am to 5:30 am India time. Use ours to compare monitors, CPCB's for the official band.
How we measured
- Data. Hourly readings from the 12 WBPCB monitors in CPCB's network, seven in Kolkata and five in Howrah, the same ones CPCB's bulletin counts, on India's NAQI scale. No satellite estimates or low-cost sensors.
- Valid days. A day counts only if a monitor reported at least 12 hourly readings. Days run midnight to midnight UTC.
- Dropped. None. Every monitor had at least 38 valid days of 40, and none was frozen (no flat days, no repeated daily values).
- City averages. The mean of each city's valid monitors that day; the last week has five days. We never use hourly peaks.
- CPCB figures. Every 4 pm bulletin from 15 September 2025 to 28 February 2026 and from 15 September to 24 October 2026.
Live readings: Kolkata, Howrah and all of India. See also India's air quality after the monsoon.
Frequently asked questions
How bad is Kolkata's air pollution in winter 2026?
So far, Moderate at worst. CPCB's bulletin put Kolkata's India NAQI between 101 and 200 on 14 of the 40 days from 15 September to 24 October 2026, and Howrah on 20, with no Poor day for either city. Last winter was worse: Kolkata was Poor on 34 days from November 2025 to February 2026, peaking at 291 on 12 December 2025.
Which area of Kolkata has the worst air pollution?
Among the 12 WBPCB monitors we track, Ghusuri in Howrah had the highest mean daily India NAQI from 1 to 24 October 2026, at 136. In Kolkata itself, Rabindra Bharati University in the north (130) and Jadavpur in the south (125) were worst. Bidhannagar (82) and Rabindra Sarobar (83) were cleanest.
When is Kali Puja 2026?
Kali Puja falls on Sunday 8 November 2026, the same day as Diwali, according to the West Bengal government's 2026 holiday list. The state has also listed 9 and 10 November as extra holidays. In 2025, Kolkata's 24-hour AQI rose from 88 to 174 over Kali Puja night in CPCB's bulletin.
What time can you burst crackers on Kali Puja in Kolkata?
The 2026 rules had not been announced as of 25 October 2026. In 2025, WBPCB and Kolkata Police allowed only certified green crackers, from 8 pm to 10 pm on Kali Puja and Diwali night, and from 6 am to 8 am on Chhath Puja. Sound crackers and sky lanterns were banned. Check WBPCB and Kolkata Police notices for 2026.
Is Howrah more polluted than Kolkata?
Yes, so far this season. Howrah's five WBPCB monitors averaged a daily India NAQI of 117 from 1 to 24 October 2026, against 102 for Kolkata's seven. CPCB's bulletin put Howrah in the Moderate band on 20 of the 40 days from 15 September, and Kolkata on 14.
