SmogRank / History / City race
Cities in Thailand, worst air first, day by day
Each measured city's average over the 30 days to every day since January 2023, worst first. Find your own city to follow it through the race, or keep to one country.
The worst cities in Thailand for PM2.5 over the 30 days to 13 Dec 2025: Samut Sakhon 42.1 µg/m³, Sukhothai 39.9 µg/m³ and Mueang Nonthaburi 34.8 µg/m³.
- 1Samut SakhonSamut Sakhon42.1
- 2SukhothaiSukhothai39.9
- 3Mueang NonthaburiNonthaburi34.8
- 4Khlong LuangPathum Thani33.9
- 5Khlong Sam WaBangkok33.8
- 6Khan Na YaoBangkok32.8
- 7KalasinKalasin32.7
- 8Ban Thai TanAng Thong32.3
- 9Nong KhaemBangkok32.1
- 10Lat KrabangBangkok31.9
- 11Maha SarakhamMaha Sarakham31.7
- 12Phra PradaengSamut Prakan31.5
- 13Bang NaBangkok31.1
- 14YasothonYasothon30.6
- 15Ban Talat BuengChon Buri30.0
- 16PhetchaburiPhetchaburi29.6
- 17Mae SaiChiang Rai29.6
- 18LamphunLamphun29.1
- 19Uthai ThaniUthai Thani29.1
- 20Ban Samae DamBangkok28.8
+ 45 more cities, 28.6 µg/m³ and below
Not counted on this day, too few days measured: Bang Pakong since 3 Nov 2025, Ratchaburi since 20 Oct 2025, Trat since 20 Oct 2025 and 5 more cities.
Cities counted each day
A city's number is its average over the 30 days, shown only when 21 of them were measured (5 of 7 on the 7-day race), the same minimum as the 30- and 7-day boards. A city whose monitors go quiet fades out where it stood rather than sliding down, so a gap never reads as cleaner air. Some large countries are thin or missing because their monitors' licences don't allow reuse. How we rank.
Not covered: the government monitoring networks of China and Turkey, which publish only on their own websites; we are building the readers for them. Most cities there are missing from this board, not clean. Why.