SmogRank / Episodes / Thailand

Northern Thailand and Laos, February 2024

For 2 days, from 9 to 10 February 2024, 12 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: 89.0 µg/m³ on 10 February, about 2.1× its usual 41.8. Readings stopped after 10 February, so this episode may have run longer.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached12in 2 countries
Days29 to 10 February 2024
Worst day9 February9 cities counted
Furthest above usual2.7×Chaiyaphum

Day by day

9 February 9 cities at twice their usual or more
LoeiUdon ThaniKhon KaenBueng KanPakxanNanSakon NakhonUttaraditPhraePhichitNakhon RatchasimaPhayaoMukdahanBuri RamKamphaeng PhetAmnat CharoenSurinChiang RaiChai NatLop BuriLamphunSing BuriChiang MaiMae SaiMae SotBan HouakhouaChiang KhongUbon RatchathaniNakhon SawanPhetchabunSi Sa KetYasothonKalasinLampangSukhothaiNong Bua LamphuChaiyaphum
6 Feb78910111213
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

SukhothaiSukhothai, 6 February: 56.0 µg/m³Sukhothai, 7 February: 55.3 µg/m³Sukhothai, 8 February: no readingSukhothai, 9 February: 77.6 µg/m³, 2.3× its usual 33.1Sukhothai, 10 February: 69.8 µg/m³, 2.1× its usual 33.0Sukhothai, 11 February: no readingSukhothai, 12 February: no readingSukhothai, 13 February: 77.4 µg/m³ChaiyaphumChaiyaphum, 6 February: 54.1 µg/m³Chaiyaphum, 7 February: 77.5 µg/m³Chaiyaphum, 8 February: no readingChaiyaphum, 9 February: 74.0 µg/m³, 2.7× its usual 27.1Chaiyaphum, 10 February: 44.5 µg/m³Chaiyaphum, 11 February: no readingChaiyaphum, 12 February: no readingChaiyaphum, 13 February: 38.8 µg/m³Nong Bua LamphuNong Bua Lamphu, 6 February: 43.1 µg/m³Nong Bua Lamphu, 7 February: 60.6 µg/m³Nong Bua Lamphu, 8 February: no readingNong Bua Lamphu, 9 February: 71.2 µg/m³, 2.6× its usual 27.1Nong Bua Lamphu, 10 February: 35.1 µg/m³Nong Bua Lamphu, 11 February: no readingNong Bua Lamphu, 12 February: no readingNong Bua Lamphu, 13 February: 44.3 µg/m³PhetchabunPhetchabun, 6 February: 38.7 µg/m³Phetchabun, 7 February: 54.3 µg/m³Phetchabun, 8 February: no readingPhetchabun, 9 February: 68.6 µg/m³, 2.0× its usual 33.6Phetchabun, 10 February: 53.9 µg/m³Phetchabun, 11 February: no readingPhetchabun, 12 February: no readingPhetchabun, 13 February: 48.1 µg/m³Nakhon SawanNakhon Sawan, 6 February: 59.5 µg/m³Nakhon Sawan, 7 February: 60.2 µg/m³Nakhon Sawan, 8 February: no readingNakhon Sawan, 9 February: 68.4 µg/m³, 2.0× its usual 33.5Nakhon Sawan, 10 February: 35.5 µg/m³Nakhon Sawan, 11 February: no readingNakhon Sawan, 12 February: no readingNakhon Sawan, 13 February: 58.9 µg/m³KalasinKalasin, 6 February: 62.6 µg/m³Kalasin, 7 February: 66.8 µg/m³Kalasin, 8 February: no readingKalasin, 9 February: 66.1 µg/m³, 2.1× its usual 31.9Kalasin, 10 February: 29.9 µg/m³Kalasin, 11 February: no readingKalasin, 12 February: no readingKalasin, 13 February: 40.0 µg/m³Ubon RatchathaniUbon Ratchathani, 6 February: 63.6 µg/m³Ubon Ratchathani, 7 February: 72.4 µg/m³Ubon Ratchathani, 8 February: no readingUbon Ratchathani, 9 February: 62.8 µg/m³, 2.0× its usual 30.8Ubon Ratchathani, 10 February: 25.3 µg/m³Ubon Ratchathani, 11 February: no readingUbon Ratchathani, 12 February: no readingUbon Ratchathani, 13 February: 39.7 µg/m³YasothonYasothon, 6 February: 54.6 µg/m³Yasothon, 7 February: 59.6 µg/m³Yasothon, 8 February: no readingYasothon, 9 February: 59.3 µg/m³, 2.1× its usual 28.8Yasothon, 10 February: 21.8 µg/m³Yasothon, 11 February: no readingYasothon, 12 February: no readingYasothon, 13 February: 33.4 µg/m³Si Sa KetSi Sa Ket, 6 February: 42.7 µg/m³Si Sa Ket, 7 February: 43.2 µg/m³Si Sa Ket, 8 February: no readingSi Sa Ket, 9 February: 50.5 µg/m³, 2.1× its usual 23.7Si Sa Ket, 10 February: no readingSi Sa Ket, 11 February: no readingSi Sa Ket, 12 February: no readingSi Sa Ket, 13 February: 29.2 µg/m³LampangLampang, 6 February: 74.6 µg/m³Lampang, 7 February: 67.9 µg/m³Lampang, 8 February: no readingLampang, 9 February: 78.2 µg/m³Lampang, 10 February: 89.0 µg/m³, 2.1× its usual 41.8Lampang, 11 February: no readingLampang, 12 February: no readingLampang, 13 February: 59.5 µg/m³Chiang KhongChiang Khong, 6 February: 45.2 µg/m³Chiang Khong, 7 February: 42.1 µg/m³Chiang Khong, 8 February: no readingChiang Khong, 9 February: 65.9 µg/m³Chiang Khong, 10 February: 55.1 µg/m³, 2.0× its usual 26.9Chiang Khong, 11 February: no readingChiang Khong, 12 February: no readingChiang Khong, 13 February: 40.7 µg/m³Ban HouakhouaBan Houakhoua, 6 February: 45.2 µg/m³Ban Houakhoua, 7 February: 42.1 µg/m³Ban Houakhoua, 8 February: no readingBan Houakhoua, 9 February: 65.9 µg/m³Ban Houakhoua, 10 February: 55.1 µg/m³, 2.0× its usual 26.9Ban Houakhoua, 11 February: no readingBan Houakhoua, 12 February: no readingBan Houakhoua, 13 February: 40.7 µg/m³6 Feb78910111213
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
ChaiyaphumChaiyaphum, Thailand1 74.09 February27.12.7×
Nong Bua LamphuNong Bua Lamphu, Thailand1 71.29 February27.12.6×
SukhothaiSukhothai, Thailand2 77.69 February33.12.3×
LampangLampang, Thailand1 89.010 February41.82.1×
KalasinKalasin, Thailand1 66.19 February31.92.1×
YasothonYasothon, Thailand1 59.39 February28.82.1×
Si Sa KetSi Sa Ket, Thailand1 50.59 February23.72.1×
PhetchabunPhetchabun, Thailand1 68.69 February33.62.0×
Nakhon SawanNakhon Sawan, Thailand1 68.49 February33.52.0×
Ubon RatchathaniUbon Ratchathani, Thailand1 62.89 February30.82.0×
Chiang KhongChiang Rai, Thailand1 55.110 February26.92.0×
Ban HouakhouaBokeo, Laos1 55.110 February26.92.0×

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 Thailand and Laos

Number 17 of 24 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 24.

Use this page

SmogRank, Northern Thailand and Laos, February 2024: 12 cities with PM2.5 at twice their usual or more, 9 to 10 February 2024, smogrank.com/episodes/2024-02-northern-thailand-and-laos (accessed 5 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.