SmogRank / Episodes / India
Bihar, India, May 2026
For 5 days, from 16 to 20 May 2026, 11 cities in India had PM2.5 at least twice their usual for the time of year. The worst reading was Bettiah, Bihar, India: 321.0 µg/m³ on 16 May, about 14× its usual 22.8.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 11 in 1 country
Days 5 16 to 20 May 2026
Worst day 16 May 5 cities counted
Furthest above usual 14× Bettiah
Day by day
Play 16 May 5 cities at twice their usual or more
Patna Bihār Sharīf Rājgīr Chāpra Gaya Munger Siwān Aurangābād Mothīhāri Sasarām Bhāgalpur Jharia Purnia Kathmandu Katihar Arāria Gorakhpur Āsansol Rānīganj Siddharthanagar Durgapur Siliguri Prayagraj Gangtok Phuntsholing Satna Lucknow Samāstipur Varanasi Hājīpur Singrauli Muzaffarpur Arrah Begusarai Kishanganj Buxar Saharsa Bettiah 13 May 14 15 16 17 18 19 20 21 22 23 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
Bettiah Bettiah, 13 May: no reading Bettiah, 14 May: 88.9 µg/m³, 3.9× usual Bettiah, 15 May: no reading Bettiah, 16 May: 321.0 µg/m³, 14× usual Bettiah, 17 May: no reading Bettiah, 18 May: 170.0 µg/m³, 7.5× usual Bettiah, 19 May: no reading Bettiah, 20 May: 24.9 µg/m³, 1.1× usual Bettiah, 21 May: no reading Bettiah, 22 May: no reading Bettiah, 23 May: 24.8 µg/m³, 1.1× usual Kishanganj Kishanganj, 13 May: 40.3 µg/m³, 1.9× usual Kishanganj, 14 May: 54.4 µg/m³, 2.5× usual Kishanganj, 15 May: 62.1 µg/m³, 2.9× usual Kishanganj, 16 May: 58.1 µg/m³, 2.7× usual Kishanganj, 17 May: 54.5 µg/m³, 2.5× usual Kishanganj, 18 May: 53.4 µg/m³, 2.5× usual Kishanganj, 19 May: 54.7 µg/m³, 2.5× usual Kishanganj, 20 May: 56.5 µg/m³, 2.6× usual Kishanganj, 21 May: 47.8 µg/m³, 2.2× usual Kishanganj, 22 May: 51.6 µg/m³, 2.4× usual Kishanganj, 23 May: 47.8 µg/m³, 2.2× usual Saharsa Saharsa, 13 May: 16.3 µg/m³, 0.6× usual Saharsa, 14 May: no reading Saharsa, 15 May: no reading Saharsa, 16 May: 128.0 µg/m³, 4.4× usual Saharsa, 17 May: 41.9 µg/m³, 1.4× usual Saharsa, 18 May: 37.7 µg/m³, 1.3× usual Saharsa, 19 May: 34.9 µg/m³, 1.2× usual Saharsa, 20 May: 62.7 µg/m³, 2.1× usual Saharsa, 21 May: 24.9 µg/m³, 0.8× usual Saharsa, 22 May: 33.7 µg/m³, 1.1× usual Saharsa, 23 May: 42.0 µg/m³, 1.4× usual Begusarai Begusarai, 13 May: 27.7 µg/m³, 1.0× usual Begusarai, 14 May: 34.8 µg/m³, 1.2× usual Begusarai, 15 May: 47.7 µg/m³, 1.7× usual Begusarai, 16 May: 67.2 µg/m³, 2.4× usual Begusarai, 17 May: 71.7 µg/m³, 2.6× usual Begusarai, 18 May: 58.6 µg/m³, 2.1× usual Begusarai, 19 May: 45.9 µg/m³, 1.6× usual Begusarai, 20 May: 67.5 µg/m³, 2.4× usual Begusarai, 21 May: 43.0 µg/m³, 1.5× usual Begusarai, 22 May: 27.8 µg/m³, 1.0× usual Begusarai, 23 May: 38.9 µg/m³, 1.4× usual Varanasi Varanasi, 13 May: 29.4 µg/m³, 1.3× usual Varanasi, 14 May: 23.8 µg/m³, 1.1× usual Varanasi, 15 May: 35.0 µg/m³, 1.6× usual Varanasi, 16 May: 45.4 µg/m³, 2.0× usual Varanasi, 17 May: 40.3 µg/m³, 1.8× usual Varanasi, 18 May: 38.8 µg/m³, 1.7× usual Varanasi, 19 May: 29.0 µg/m³, 1.3× usual Varanasi, 20 May: 33.3 µg/m³, 1.5× usual Varanasi, 21 May: 38.4 µg/m³, 1.7× usual Varanasi, 22 May: 29.5 µg/m³, 1.3× usual Varanasi, 23 May: 40.4 µg/m³, 1.8× usual Singrauli Singrauli, 13 May: no reading Singrauli, 14 May: 60.1 µg/m³, 1.3× usual Singrauli, 15 May: 70.7 µg/m³, 1.6× usual Singrauli, 16 May: no reading Singrauli, 17 May: 100.0 µg/m³, 2.2× usual Singrauli, 18 May: no reading Singrauli, 19 May: 93.6 µg/m³, 2.1× usual Singrauli, 20 May: 97.9 µg/m³, 2.2× usual Singrauli, 21 May: 98.8 µg/m³, 2.2× usual Singrauli, 22 May: 109.0 µg/m³, 2.4× usual Singrauli, 23 May: 76.8 µg/m³, 1.7× usual Hājīpur Hājīpur, 13 May: 56.0 µg/m³, 1.2× usual Hājīpur, 14 May: 45.5 µg/m³, 1.0× usual Hājīpur, 15 May: 72.9 µg/m³, 1.6× usual Hājīpur, 16 May: 87.7 µg/m³, 1.9× usual Hājīpur, 17 May: 96.7 µg/m³, 2.1× usual Hājīpur, 18 May: 78.5 µg/m³, 1.7× usual Hājīpur, 19 May: 67.5 µg/m³, 1.5× usual Hājīpur, 20 May: 83.3 µg/m³, 1.8× usual Hājīpur, 21 May: 75.1 µg/m³, 1.7× usual Hājīpur, 22 May: 62.2 µg/m³, 1.4× usual Hājīpur, 23 May: 70.3 µg/m³, 1.6× usual Arrah Arrah, 13 May: 16.2 µg/m³, 1.0× usual Arrah, 14 May: 16.0 µg/m³, 1.0× usual Arrah, 15 May: 23.0 µg/m³, 1.4× usual Arrah, 16 May: 26.5 µg/m³, 1.6× usual Arrah, 17 May: 37.1 µg/m³, 2.3× usual Arrah, 18 May: 32.3 µg/m³, 2.0× usual Arrah, 19 May: 21.7 µg/m³, 1.3× usual Arrah, 20 May: 28.6 µg/m³, 1.8× usual Arrah, 21 May: 24.5 µg/m³, 1.5× usual Arrah, 22 May: 20.4 µg/m³, 1.3× usual Arrah, 23 May: 32.2 µg/m³, 2.0× usual Buxar Buxar, 13 May: 30.7 µg/m³, 1.1× usual Buxar, 14 May: 27.1 µg/m³, 1.0× usual Buxar, 15 May: 34.3 µg/m³, 1.2× usual Buxar, 16 May: 36.0 µg/m³, 1.3× usual Buxar, 17 May: 40.5 µg/m³, 1.4× usual Buxar, 18 May: 94.6 µg/m³, 3.3× usual Buxar, 19 May: 123.0 µg/m³, 4.3× usual Buxar, 20 May: 56.3 µg/m³, 2.0× usual Buxar, 21 May: 55.8 µg/m³, 2.0× usual Buxar, 22 May: no reading Buxar, 23 May: 76.3 µg/m³, 2.7× usual Samāstipur Samāstipur, 13 May: no reading Samāstipur, 14 May: no reading Samāstipur, 15 May: no reading Samāstipur, 16 May: no reading Samāstipur, 17 May: no reading Samāstipur, 18 May: no reading Samāstipur, 19 May: 52.4 µg/m³, 2.0× usual Samāstipur, 20 May: 18.7 µg/m³, 0.7× usual Samāstipur, 21 May: no reading Samāstipur, 22 May: no reading Samāstipur, 23 May: no reading Muzaffarpur Muzaffarpur, 13 May: 47.3 µg/m³, 1.5× usual Muzaffarpur, 14 May: 42.2 µg/m³, 1.3× usual Muzaffarpur, 15 May: 51.8 µg/m³, 1.6× usual Muzaffarpur, 16 May: 46.0 µg/m³, 1.4× usual Muzaffarpur, 17 May: 47.5 µg/m³, 1.5× usual Muzaffarpur, 18 May: 53.7 µg/m³, 1.7× usual Muzaffarpur, 19 May: 44.7 µg/m³, 1.4× usual Muzaffarpur, 20 May: 76.0 µg/m³, 2.3× usual Muzaffarpur, 21 May: 44.5 µg/m³, 1.4× usual Muzaffarpur, 22 May: 45.3 µg/m³, 1.4× usual Muzaffarpur, 23 May: 53.6 µg/m³, 1.7× usual 13 May 15 17 19 21 23 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. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Bettiah Bihar, India 2 16 May 22.8 14× Saharsa Bihar, India 1 16 May 29.4 4.4× Buxar Bihar, India 2 19 May 28.5 4.3× Kishanganj Bihar, India 5 15 May 21.5 2.9× Begusarai Bihar, India 4 17 May 28.0 2.6× Singrauli Madhya Pradesh, India 3 22 May 45.2 2.4× Muzaffarpur Bihar, India 1 20 May 32.4 2.3× Arrah Bihar, India 2 17 May 16.1 2.3× Hājīpur Bihar, India 1 17 May 45.1 2.1× Varanasi Uttar Pradesh, India 1 16 May 22.3 2.0× Samāstipur Bihar, India 1 19 May 26.1 2.0×
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 35 of 54 episodes in India since our records began, by cities reached.
North-western India, October 2025 170 North-western India, September 2026 57 North-western India, July 2026 51 North-western India, June 2025 47 North-eastern India, March and April 2025 45 North-western India, November 2025 27 North-western India, April 2026 26 North-western India, April and May 2025 26 North-western India and Pakistan, March 2026 25 North-western India, May 2025 23 North-eastern India, July 2026 22 North-eastern India, April 2025 20 Bihar, India, May 2026 11 Bars: cities reached; colour: the level of the episode's highest daily reading. All 54 .
Use this page SmogRank, Bihar, India, May 2026: 11 cities with PM2.5 at twice their usual or more, 16 to 20 May 2026, smogrank.com/episodes/2026-05-bihar-india (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.
