SmogRank / Episodes / India

North-eastern India and Bhutan, September 2026

For 6 days, from 4 to 9 September 2026, 14 cities in India and Bhutan had PM2.5 at least twice their usual for the time of year. The worst reading was Bihār Sharīf, Bihar, India: 107.0 µg/m³ on 4 September, about 2.0× its usual 52.4.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached14in 2 countries
Days64 to 9 September 2026
Worst day6 September8 cities counted
Furthest above usual6.2×Sasarām

Day by day

6 September 8 cities at twice their usual or more
RānīganjĀsansolJhariaKolkataHaldiaKatiharBaripādaRairangpurPurniaBegusaraiSaharsaKishanganjArāriaRājgīrJodaSamāstipurDhakaRourkelaPatnaHājīpurSiliguriMuzaffarpurArrahChāpraDera Colliery TownshipAngulBhubaneswarGangtokMothīhāriSiwānBettiahNalbāriGuwahatiGorakhpurDurgapurGayaBihār SharīfShrīrāmpurCuttackByasanagarPhuntsholingKeonjhargarhMungerAgartalaBarbilBhāgalpurBelpaharSasarām
1 Sep23456789101112
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

Bihār SharīfBihār Sharīf, 1 September: no readingBihār Sharīf, 2 September: no readingBihār Sharīf, 3 September: 93.8 µg/m³Bihār Sharīf, 4 September: 107.0 µg/m³, 2.0× its usual 52.4Bihār Sharīf, 5 September: 12.5 µg/m³Bihār Sharīf, 6 September: no readingBihār Sharīf, 7 September: no readingBihār Sharīf, 8 September: 17.8 µg/m³Bihār Sharīf, 9 September: 14.2 µg/m³Bihār Sharīf, 10 September: 7.4 µg/m³Bihār Sharīf, 11 September: no readingBihār Sharīf, 12 September: no readingBhāgalpurBhāgalpur, 1 September: 44.8 µg/m³Bhāgalpur, 2 September: 74.2 µg/m³Bhāgalpur, 3 September: 72.2 µg/m³Bhāgalpur, 4 September: 82.9 µg/m³, 3.3× its usual 25.3Bhāgalpur, 5 September: 80.8 µg/m³, 3.2× its usual 25.3Bhāgalpur, 6 September: 89.8 µg/m³, 3.5× its usual 25.8Bhāgalpur, 7 September: no readingBhāgalpur, 8 September: 37.2 µg/m³Bhāgalpur, 9 September: 41.3 µg/m³Bhāgalpur, 10 September: 50.5 µg/m³Bhāgalpur, 11 September: 25.6 µg/m³Bhāgalpur, 12 September: 24.7 µg/m³BelpaharBelpahar, 1 September: 15.5 µg/m³Belpahar, 2 September: 13.7 µg/m³Belpahar, 3 September: 16.8 µg/m³Belpahar, 4 September: 56.9 µg/m³, 4.2× its usual 13.4Belpahar, 5 September: 35.6 µg/m³, 2.7× its usual 13.4Belpahar, 6 September: 52.4 µg/m³, 3.9× its usual 13.5Belpahar, 7 September: 55.2 µg/m³, 4.1× its usual 13.4Belpahar, 8 September: 66.8 µg/m³, 4.9× its usual 13.5Belpahar, 9 September: 53.3 µg/m³, 3.8× its usual 14.1Belpahar, 10 September: 11.1 µg/m³Belpahar, 11 September: 6.3 µg/m³Belpahar, 12 September: 9.0 µg/m³SasarāmSasarām, 1 September: 49.8 µg/m³Sasarām, 2 September: 39.0 µg/m³Sasarām, 3 September: 56.5 µg/m³Sasarām, 4 September: 38.1 µg/m³, 3.7× its usual 10.4Sasarām, 5 September: 28.9 µg/m³, 2.8× its usual 10.4Sasarām, 6 September: 63.7 µg/m³, 5.4× its usual 11.7Sasarām, 7 September: 35.6 µg/m³, 3.0× its usual 11.8Sasarām, 8 September: no readingSasarām, 9 September: 76.8 µg/m³, 6.2× its usual 12.4Sasarām, 10 September: no readingSasarām, 11 September: no readingSasarām, 12 September: 11.4 µg/m³MungerMunger, 1 September: no readingMunger, 2 September: no readingMunger, 3 September: no readingMunger, 4 September: no readingMunger, 5 September: 59.8 µg/m³, 2.6× its usual 22.6Munger, 6 September: no readingMunger, 7 September: 22.8 µg/m³Munger, 8 September: 19.4 µg/m³Munger, 9 September: no readingMunger, 10 September: no readingMunger, 11 September: no readingMunger, 12 September: 15.0 µg/m³ShrīrāmpurShrīrāmpur, 1 September: 20.6 µg/m³Shrīrāmpur, 2 September: 27.2 µg/m³Shrīrāmpur, 3 September: 33.8 µg/m³Shrīrāmpur, 4 September: 28.3 µg/m³Shrīrāmpur, 5 September: 36.3 µg/m³, 2.1× its usual 17.0Shrīrāmpur, 6 September: 34.6 µg/m³, 2.0× its usual 17.2Shrīrāmpur, 7 September: 32.5 µg/m³Shrīrāmpur, 8 September: 29.9 µg/m³Shrīrāmpur, 9 September: 27.4 µg/m³Shrīrāmpur, 10 September: 20.0 µg/m³Shrīrāmpur, 11 September: 16.0 µg/m³Shrīrāmpur, 12 September: 19.1 µg/m³KeonjhargarhKeonjhargarh, 1 September: no readingKeonjhargarh, 2 September: 33.7 µg/m³Keonjhargarh, 3 September: 14.9 µg/m³Keonjhargarh, 4 September: 18.2 µg/m³Keonjhargarh, 5 September: 30.3 µg/m³, 2.2× its usual 13.6Keonjhargarh, 6 September: 25.3 µg/m³Keonjhargarh, 7 September: 34.8 µg/m³, 2.6× its usual 13.6Keonjhargarh, 8 September: 25.7 µg/m³Keonjhargarh, 9 September: 28.5 µg/m³, 2.1× its usual 13.8Keonjhargarh, 10 September: 20.6 µg/m³Keonjhargarh, 11 September: 18.1 µg/m³Keonjhargarh, 12 September: 22.0 µg/m³AgartalaAgartala, 1 September: 21.7 µg/m³Agartala, 2 September: 22.7 µg/m³Agartala, 3 September: 23.3 µg/m³Agartala, 4 September: 29.8 µg/m³Agartala, 5 September: 29.6 µg/m³, 2.8× its usual 10.5Agartala, 6 September: 30.1 µg/m³, 2.8× its usual 10.7Agartala, 7 September: 34.2 µg/m³Agartala, 8 September: 35.9 µg/m³Agartala, 9 September: 28.9 µg/m³Agartala, 10 September: 24.4 µg/m³Agartala, 11 September: 23.2 µg/m³Agartala, 12 September: 23.3 µg/m³DurgapurDurgapur, 1 September: 14.6 µg/m³Durgapur, 2 September: 25.8 µg/m³Durgapur, 3 September: 28.6 µg/m³Durgapur, 4 September: 24.5 µg/m³Durgapur, 5 September: 32.7 µg/m³Durgapur, 6 September: 41.2 µg/m³, 2.0× its usual 20.3Durgapur, 7 September: 26.7 µg/m³Durgapur, 8 September: 29.6 µg/m³Durgapur, 9 September: 29.5 µg/m³Durgapur, 10 September: 12.0 µg/m³Durgapur, 11 September: 12.2 µg/m³Durgapur, 12 September: 17.2 µg/m³BarbilBarbil, 1 September: 22.9 µg/m³Barbil, 2 September: 31.6 µg/m³Barbil, 3 September: 9.3 µg/m³Barbil, 4 September: 30.5 µg/m³Barbil, 5 September: 21.1 µg/m³Barbil, 6 September: 34.6 µg/m³, 2.0× its usual 17.1Barbil, 7 September: 53.3 µg/m³, 3.2× its usual 16.8Barbil, 8 September: 35.4 µg/m³, 2.1× its usual 17.1Barbil, 9 September: 31.3 µg/m³Barbil, 10 September: 21.4 µg/m³Barbil, 11 September: 9.4 µg/m³Barbil, 12 September: 13.7 µg/m³PhuntsholingPhuntsholing, 1 September: 1.4 µg/m³Phuntsholing, 2 September: 3.0 µg/m³Phuntsholing, 3 September: 5.2 µg/m³Phuntsholing, 4 September: 10.1 µg/m³Phuntsholing, 5 September: 24.2 µg/m³Phuntsholing, 6 September: 29.9 µg/m³, 2.6× its usual 11.4Phuntsholing, 7 September: 27.2 µg/m³Phuntsholing, 8 September: 41.6 µg/m³Phuntsholing, 9 September: 35.3 µg/m³Phuntsholing, 10 September: 21.3 µg/m³Phuntsholing, 11 September: 10.5 µg/m³Phuntsholing, 12 September: 8.7 µg/m³GayaGaya, 1 September: 53.4 µg/m³Gaya, 2 September: 10.5 µg/m³Gaya, 3 September: 61.9 µg/m³Gaya, 4 September: 32.7 µg/m³Gaya, 5 September: 26.3 µg/m³Gaya, 6 September: 29.0 µg/m³Gaya, 7 September: 28.7 µg/m³Gaya, 8 September: 49.3 µg/m³, 2.0× its usual 24.6Gaya, 9 September: 24.3 µg/m³Gaya, 10 September: 22.3 µg/m³Gaya, 11 September: 23.2 µg/m³Gaya, 12 September: 22.9 µg/m³ByasanagarByasanagar, 1 September: no readingByasanagar, 2 September: 43.8 µg/m³Byasanagar, 3 September: 39.2 µg/m³Byasanagar, 4 September: 31.6 µg/m³Byasanagar, 5 September: 34.3 µg/m³Byasanagar, 6 September: 34.7 µg/m³Byasanagar, 7 September: 32.3 µg/m³Byasanagar, 8 September: 41.0 µg/m³, 2.3× its usual 17.9Byasanagar, 9 September: 32.6 µg/m³Byasanagar, 10 September: 17.8 µg/m³Byasanagar, 11 September: 14.8 µg/m³Byasanagar, 12 September: 25.7 µg/m³CuttackCuttack, 1 September: 20.1 µg/m³Cuttack, 2 September: 22.8 µg/m³Cuttack, 3 September: 16.4 µg/m³Cuttack, 4 September: 26.1 µg/m³Cuttack, 5 September: 19.4 µg/m³Cuttack, 6 September: 17.2 µg/m³Cuttack, 7 September: 19.7 µg/m³Cuttack, 8 September: 27.0 µg/m³Cuttack, 9 September: 40.7 µg/m³, 2.3× its usual 18.0Cuttack, 10 September: 29.6 µg/m³Cuttack, 11 September: 11.3 µg/m³Cuttack, 12 September: 12.6 µg/m³1 Sep357911
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
SasarāmBihar, India5 76.89 September12.46.2×
BelpaharOdisha, India6 66.88 September13.54.9×
BhāgalpurBihar, India3 89.86 September25.83.5×
BarbilOdisha, India3 53.37 September16.83.2×
AgartalaTripura, India2 30.16 September10.72.8×
MungerBihar, India1 59.85 September22.62.6×
KeonjhargarhOdisha, India3 34.87 September13.62.6×
PhuntsholingChukha, Bhutan1 29.96 September11.42.6×
ByasanagarOdisha, India1 41.08 September17.92.3×
CuttackOdisha, India1 40.79 September18.02.3×
ShrīrāmpurWest Bengal, India2 36.35 September17.02.1×
Bihār SharīfBihar, India1 107.04 September52.42.0×
GayaBihar, India1 49.38 September24.62.0×
DurgapurWest Bengal, India1 41.26 September20.32.0×

Daily means in µg/m³, over the days each city counted in this episode. Highest: its highest of those days. Usual: the city's median for the time of year of that day (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that, with a usual under 5 µg/m³ taken as 5.

Against other episodes in India and Bhutan

Number 18 of 54 episodes in India and Bhutan since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 54.

Use this page

SmogRank, North-eastern India and Bhutan, September 2026: 14 cities with PM2.5 at twice their usual or more, 4 to 9 September 2026, smogrank.com/episodes/2026-09-north-eastern-india-and-bhutan (accessed 4 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.