SmogRank / Episodes / Thailand

North-western Thailand and Laos, February 2023

For 1 day, on 15 February 2023, 10 cities in Thailand and Laos had PM2.5 at least twice their usual for the time of year. The worst reading was Lampang, Lampang, Thailand: 182.0 µg/m³ on 15 February, about 3.7× its usual 48.8.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached10in 2 countries
Days115 February 2023
Worst day15 February10 cities counted
Furthest above usual4.6×Ban Houakhoua

Day by day

15 February 10 cities at twice their usual or more
UttaraditTakMae SotPhichitLoeiPhetchabunVientianeTha BoNong Bua LamphuUdon ThaniYangonPakxanKalasinRoi EtPhraeKamphaeng PhetMae SaiChiang MaiSukhothaiChiang RaiLamphunPhayaoLampangBan Houakhoua
12 Feb131415161718
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

LampangLampang, 12 February: no readingLampang, 13 February: no readingLampang, 14 February: no readingLampang, 15 February: 182.0 µg/m³, 3.7× its usual 48.8Lampang, 16 February: no readingLampang, 17 February: no readingLampang, 18 February: no readingPhayaoPhayao, 12 February: no readingPhayao, 13 February: no readingPhayao, 14 February: no readingPhayao, 15 February: 136.0 µg/m³, 3.4× its usual 39.5Phayao, 16 February: no readingPhayao, 17 February: no readingPhayao, 18 February: no readingBan HouakhouaBan Houakhoua, 12 February: no readingBan Houakhoua, 13 February: no readingBan Houakhoua, 14 February: no readingBan Houakhoua, 15 February: 130.0 µg/m³, 4.6× its usual 28.1Ban Houakhoua, 16 February: no readingBan Houakhoua, 17 February: no readingBan Houakhoua, 18 February: no readingLamphunLamphun, 12 February: no readingLamphun, 13 February: no readingLamphun, 14 February: no readingLamphun, 15 February: 124.0 µg/m³, 3.4× its usual 36.0Lamphun, 16 February: no readingLamphun, 17 February: no readingLamphun, 18 February: no readingSukhothaiSukhothai, 12 February: no readingSukhothai, 13 February: no readingSukhothai, 14 February: no readingSukhothai, 15 February: 103.0 µg/m³, 3.0× its usual 34.5Sukhothai, 16 February: no readingSukhothai, 17 February: no readingSukhothai, 18 February: no readingChiang RaiChiang Rai, 12 February: no readingChiang Rai, 13 February: no readingChiang Rai, 14 February: no readingChiang Rai, 15 February: 98.0 µg/m³, 3.3× its usual 29.9Chiang Rai, 16 February: no readingChiang Rai, 17 February: no readingChiang Rai, 18 February: no readingMae SaiMae Sai, 12 February: no readingMae Sai, 13 February: no readingMae Sai, 14 February: no readingMae Sai, 15 February: 94.7 µg/m³, 2.5× its usual 38.0Mae Sai, 16 February: no readingMae Sai, 17 February: no readingMae Sai, 18 February: no readingPhraePhrae, 12 February: no readingPhrae, 13 February: no readingPhrae, 14 February: no readingPhrae, 15 February: 92.4 µg/m³, 2.3× its usual 40.3Phrae, 16 February: no readingPhrae, 17 February: no readingPhrae, 18 February: no readingKamphaeng PhetKamphaeng Phet, 12 February: no readingKamphaeng Phet, 13 February: no readingKamphaeng Phet, 14 February: no readingKamphaeng Phet, 15 February: 91.2 µg/m³, 2.5× its usual 36.6Kamphaeng Phet, 16 February: no readingKamphaeng Phet, 17 February: no readingKamphaeng Phet, 18 February: no readingChiang MaiChiang Mai, 12 February: no readingChiang Mai, 13 February: no readingChiang Mai, 14 February: no readingChiang Mai, 15 February: 88.9 µg/m³, 3.0× its usual 29.2Chiang Mai, 16 February: no readingChiang Mai, 17 February: no readingChiang Mai, 18 February: no reading12 Feb131415161718
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
Ban HouakhouaBokeo, Laos1 130.015 February28.14.6×
LampangLampang, Thailand1 182.015 February48.83.7×
PhayaoPhayao, Thailand1 136.015 February39.53.4×
LamphunLamphun, Thailand1 124.015 February36.03.4×
Chiang RaiChiang Rai, Thailand1 98.015 February29.93.3×
SukhothaiSukhothai, Thailand1 103.015 February34.53.0×
Chiang MaiChiang Mai, Thailand1 88.915 February29.23.0×
Mae SaiChiang Rai, Thailand1 94.715 February38.02.5×
Kamphaeng PhetKamphaeng Phet, Thailand1 91.215 February36.62.5×
PhraePhrae, Thailand1 92.415 February40.32.3×

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 Thailand and Laos

Number 15 of 23 episodes in Thailand and Laos since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 23.

Use this page

SmogRank, North-western Thailand and Laos, February 2023: 10 cities with PM2.5 at twice their usual or more, 15 February 2023, smogrank.com/episodes/2023-02-north-western-thailand-and-laos (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.