SmogRank / Thailand / Nan / Nan

Nan, month by month

Nan has a measured daily mean on 621 days since 1 January 2023. Its worst month was April 2026, at 182 US AQI (99.3 µg/m³), 6th of 2,941 cities on that month's world ranking. Its cleanest was September 2025, at 49 US AQI (8.9 µg/m³).

Every month since 2023

2026too few days for a mean (a year needs 200)133 days measured
Jan9 daysFeb106#170Mar152#57Apr182#6May19 daysJunnoneJulnoneAugnoneSep9 daysOct68#142
2025too few days for a mean (a year needs 256)209 days measured
Jan5 daysFeb132#49Mar165#20Apr122#63May74#237Jun56#875JulnoneAug6 daysSep49#918Oct10 daysNov11 daysDec76#417
2024too few days for a mean (a year needs 257)195 days measured
Jan98#97Feb145#21Mar19 daysApr165#7May108#45Jun70#102Jul19 daysAug18 daysSep5 daysOct2 daysNov3 daysDec1 day
2023too few days for a mean (a year needs 256)84 days measured
Jan119#29Feb1 dayMar9 daysApr16 daysMay15 daysJun12 daysJul3 daysAug2 daysSep3 daysOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Nan's measured days, with its place on that month's world ranking under it. A month has a mean once 70% of its days are measured, the rule the monthly rankings use; under that, the square gives the days measured. Each square opens that month's ranking with Nan marked; each year, the year's. A dashed square is the running month, so far.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

Months without a mean, and why

29 months
MonthWhy
Sep 20269 of 30 days measured; a month needs 21. The others: 1 with readings for part of the day (a day needs 18 hours), 20 with under 18 hours of readings or readings that failed our checks.
Aug 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jun 2026No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
May 202619 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Jan 20269 of 31 days measured; a month needs 22. The others: 22 with under 18 hours of readings or readings that failed our checks.
Nov 202511 of 30 days measured; a month needs 21. The others: 19 with under 18 hours of readings or readings that failed our checks.
Oct 202510 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Aug 20256 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Jul 2025No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jan 20255 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Dec 20241 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Nov 20243 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Oct 20242 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks.
Sep 20245 of 30 days measured; a month needs 21. The others: 25 with under 18 hours of readings or readings that failed our checks.
Aug 202418 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks.
Jul 202419 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Mar 202419 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Dec 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Sep 20233 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Aug 20232 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks.
Jul 20233 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 27 with under 18 hours of readings or readings that failed our checks.
Jun 202312 of 30 days measured; a month needs 21. The others: 18 with under 18 hours of readings or readings that failed our checks.
May 202315 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks.
Apr 202316 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 12 with under 18 hours of readings or readings that failed our checks.
Mar 20239 of 31 days measured; a month needs 22. The others: 19 missing from OpenAQ's archive, 3 with under 18 hours of readings or readings that failed our checks.
Feb 20231 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive, 2 with under 18 hours of readings or readings that failed our checks.

A day counts once 18 hours of it are measured; a month needs 70% of its days.

Nan's worst months

MonthUS AQIDays measuredWorld rankEpisode
April 2026 18299.3 µg/m³30 of 306thof 2,941Northern Thailand and Laos, April 2026
March 2025 16575.8 µg/m³27 of 3120thof 2,862–
April 2024 16575.6 µg/m³29 of 307thof 2,520Thailand and Laos, April and May 2024
March 2026 15257.3 µg/m³28 of 3157thof 2,971–
February 2024 14553.4 µg/m³21 of 2921stof 2,486–
February 2025 13248.1 µg/m³28 of 2849thof 2,633–

Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.

Nan's worst days

DayUS AQIEpisode
7 Apr 2023 306228.0 µg/m³Northern Thailand and Laos around Bangkok, 5 to 8 April 2023
18 Apr 2026 280205.0 µg/m³Northern Thailand and Laos, April 2026
27 Mar 2023 272197.0 µg/m³Northern Thailand and Laos, March and April 2023
1 Apr 2023 248173.0 µg/m³Northern Thailand and Laos, March and April 2023
26 Mar 2023 240165.0 µg/m³Northern Thailand and Laos, March and April 2023
8 Apr 2023 236161.0 µg/m³Northern Thailand and Laos around Bangkok, 5 to 8 April 2023
28 Mar 2023 222147.0 µg/m³Northern Thailand and Laos, March and April 2023
2 Apr 2026 215140.0 µg/m³–
13 Apr 2026 215140.0 µg/m³Northern Thailand and Laos, April 2026
5 Apr 2023 214139.0 µg/m³Northern Thailand and Laos around Bangkok, 5 to 8 April 2023

Daily means, the highest since 1 Jan 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.

Use this history

SmogRank, PM2.5 monthly and daily means, Nan, Thailand, 1 Jan 2023 – 12 Oct 2026. Monitor data from Air4Thai via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/th/nan/history (accessed 12 Oct 2026).

Download chart (PNG)

You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.

Nan now: the last 24 hours, its ranks today and the last 12 months day by day.

Updated 2026-10-12 18:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).