SmogRank / Episodes / India

North-eastern India, September 2026

For 2 days, from 28 to 29 September 2026, 10 cities in India had PM2.5 at least twice their usual for the time of year. The worst reading was Kolkata, West Bengal, India: 65.0 µg/m³ on 29 September, about 2.7× its usual 24.5.

Likely wildfire smokeFires were detected within 300 km of the city on 87% of the counted city-days.
Cities reached10in 1 country
Days228 to 29 September 2026
Worst day29 September8 cities counted
Furthest above usual4.7×Purnia

Day by day

29 September 8 cities at twice their usual or more
ĀsansolRānīganjDurgapurJhariaBhāgalpurRairangpurBaripādaKatiharRājgīrBihār SharīfSaharsaGayaBarbilJodaSamāstipurArāriaRourkelaKishanganjPatnaHājīpurMuzaffarpurArrahChāpraDhakaVaranasiBilāspurPurniaShrīrāmpurHaldiaKeonjhargarhAgartalaKolkataBelpaharBegusaraiSasarāmBhelai
25 Sep26272829301 Oct2
Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.

How it spread

PurniaPurnia, 25 September: 137.0 µg/m³, 5.4× usualPurnia, 26 September: 49.7 µg/m³, 2.0× usualPurnia, 27 September: no readingPurnia, 28 September: no readingPurnia, 29 September: 51.8 µg/m³, 2.0× usualPurnia, 30 September: no readingPurnia, 1 October: no readingPurnia, 2 October: no readingSasarāmSasarām, 25 September: 12.0 µg/m³, 0.9× usualSasarām, 26 September: 20.0 µg/m³, 1.6× usualSasarām, 27 September: 33.0 µg/m³, 2.6× usualSasarām, 28 September: 33.8 µg/m³, 2.6× usualSasarām, 29 September: 49.0 µg/m³, 3.8× usualSasarām, 30 September: no readingSasarām, 1 October: no readingSasarām, 2 October: no readingBegusaraiBegusarai, 25 September: no readingBegusarai, 26 September: 11.4 µg/m³, 1.0× usualBegusarai, 27 September: 25.9 µg/m³, 2.2× usualBegusarai, 28 September: 32.1 µg/m³, 2.7× usualBegusarai, 29 September: 35.7 µg/m³, 3.0× usualBegusarai, 30 September: no readingBegusarai, 1 October: no readingBegusarai, 2 October: no readingKolkataKolkata, 25 September: 12.8 µg/m³, 0.5× usualKolkata, 26 September: 18.4 µg/m³, 0.8× usualKolkata, 27 September: 35.8 µg/m³, 1.5× usualKolkata, 28 September: 48.7 µg/m³, 2.0× usualKolkata, 29 September: 65.0 µg/m³, 2.7× usualKolkata, 30 September: no readingKolkata, 1 October: no readingKolkata, 2 October: no readingBhelaiBhelai, 25 September: 7.1 µg/m³, 0.7× usualBhelai, 26 September: 8.1 µg/m³, 0.8× usualBhelai, 27 September: no readingBhelai, 28 September: 47.0 µg/m³, 4.7× usualBhelai, 29 September: 24.5 µg/m³, 2.5× usualBhelai, 30 September: no readingBhelai, 1 October: no readingBhelai, 2 October: no readingAgartalaAgartala, 25 September: 16.2 µg/m³, 0.9× usualAgartala, 26 September: 20.7 µg/m³, 1.1× usualAgartala, 27 September: 28.9 µg/m³, 1.5× usualAgartala, 28 September: 46.6 µg/m³, 2.5× usualAgartala, 29 September: 50.5 µg/m³, 2.7× usualAgartala, 30 September: no readingAgartala, 1 October: no readingAgartala, 2 October: no readingHaldiaHaldia, 25 September: 9.5 µg/m³, 0.5× usualHaldia, 26 September: 12.1 µg/m³, 0.6× usualHaldia, 27 September: 22.9 µg/m³, 1.1× usualHaldia, 28 September: 41.1 µg/m³, 2.0× usualHaldia, 29 September: 40.7 µg/m³, 2.0× usualHaldia, 30 September: no readingHaldia, 1 October: no readingHaldia, 2 October: no readingKeonjhargarhKeonjhargarh, 25 September: 18.4 µg/m³, 1.3× usualKeonjhargarh, 26 September: 20.6 µg/m³, 1.5× usualKeonjhargarh, 27 September: 26.9 µg/m³, 1.9× usualKeonjhargarh, 28 September: 35.5 µg/m³, 2.5× usualKeonjhargarh, 29 September: 19.6 µg/m³, 1.4× usualKeonjhargarh, 30 September: no readingKeonjhargarh, 1 October: no readingKeonjhargarh, 2 October: no readingBelpaharBelpahar, 25 September: 4.8 µg/m³, 0.2× usualBelpahar, 26 September: 8.7 µg/m³, 0.4× usualBelpahar, 27 September: 20.9 µg/m³, 0.9× usualBelpahar, 28 September: no readingBelpahar, 29 September: 62.5 µg/m³, 2.8× usualBelpahar, 30 September: no readingBelpahar, 1 October: no readingBelpahar, 2 October: no readingShrīrāmpurShrīrāmpur, 25 September: 14.0 µg/m³, 0.7× usualShrīrāmpur, 26 September: 18.9 µg/m³, 0.9× usualShrīrāmpur, 27 September: no readingShrīrāmpur, 28 September: no readingShrīrāmpur, 29 September: 42.1 µg/m³, 2.0× usualShrīrāmpur, 30 September: no readingShrīrāmpur, 1 October: no readingShrīrāmpur, 2 October: no reading25 Sep26272829301 Oct2
Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

Every city it reached

CityDaysHighestUsualAbove usual
PurniaBihar, India1 137.025 September25.35.4×
BhelaiChhattisgarh, India1 47.028 September10.04.7×
SasarāmBihar, India2 49.029 September12.93.8×
BegusaraiBihar, India2 35.729 September11.83.0×
BelpaharOdisha, India1 62.529 September22.42.8×
AgartalaTripura, India2 50.529 September18.82.7×
KolkataWest Bengal, India2 65.029 September24.52.7×
KeonjhargarhOdisha, India1 35.528 September14.12.5×
HaldiaWest Bengal, India2 41.128 September20.12.0×
ShrīrāmpurWest Bengal, India1 42.129 September21.02.0×

Daily means in µg/m³. Usual: the city's median for this time of year (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that.

Against other episodes in India

Number 4 of 5 episodes in India since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading.

Use this page

SmogRank, North-eastern India, September 2026: 10 cities with PM2.5 at twice their usual or more, 28 to 29 September 2026, smogrank.com/episodes/2026-09-north-eastern-india-2 (accessed 2 October 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms.

An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes. Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source. Fire detections from NASA FIRMS; smoke maps from NOAA HMS.