SmogRank / Thailand / Roi Et / Roi Et

Roi Et, month by month

Roi Et has a measured daily mean on 656 days since 1 January 2023. Its worst month was April 2024, at 122 US AQI (44.1 µg/m³), 40th of 2,520 cities on that month's world ranking. Its cleanest was August 2026, at 32 US AQI (5.8 µg/m³).

Every month since 2023

202674 so far255 days measured325th of 2,793 in the world
Jan94#155Feb82#354Mar92#244Apr116#118May73#264Jun52#674Jul3 daysAug32#2,536Sep53#636Oct67#175
2025too few days for a mean (a year needs 256)213 days measured
Jan5 daysFeb80#288Mar115#141Apr109#95May18 daysJun71#225JulnoneAug6 daysSep37#1,805Oct10 daysNov12 daysDec73#480
2024too few days for a mean (a year needs 257)115 days measured
Jan70#294Feb12 daysMar19 daysApr122#40May81#90Jun3 daysJulnoneAugnoneSepnoneOctnoneNovnoneDecnone
2023too few days for a mean (a year needs 256)73 days measured
Jan71#151Feb2 daysMar9 daysApr18 daysMay15 daysJun6 daysJulnoneAugnoneSepnoneOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Roi Et'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 Roi Et 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

27 months
MonthWhy
Jul 20263 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Nov 202512 of 30 days measured; a month needs 21. The others: 18 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.
May 202518 of 31 days measured; a month needs 22. The others: 13 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 2024No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 2024No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Sep 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 2024No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 2024No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jun 20243 of 30 days measured; a month needs 21. The others: 27 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.
Feb 202412 of 29 days measured; a month needs 21. The others: 1 missing from OpenAQ's archive, 16 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 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 2023No day measured. The others: 1 missing from OpenAQ's archive, 30 with under 18 hours of readings or readings that failed our checks.
Jun 20236 of 30 days measured; a month needs 21. The others: 24 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 202318 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 10 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 20232 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive, 1 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.

Roi Et's worst months

MonthUS AQIDays measuredWorld rankEpisode
April 2024 12244.1 µg/m³29 of 3040thof 2,520Thailand and Laos, April and May 2024
April 2026 11641.5 µg/m³29 of 30118thof 2,941–
March 2025 11541.2 µg/m³26 of 31141stof 2,862Thailand and Laos, March 2025
April 2025 10938.6 µg/m³22 of 3095thof 2,951–
January 2026 9432.0 µg/m³31 of 31155thof 2,617–
March 2026 9231.1 µg/m³31 of 31244thof 2,971–

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.

Roi Et's worst days

DayUS AQIEpisode
25 Mar 2025 17387.2 µg/m³Thailand and Laos, March 2025
26 Mar 2025 17183.4 µg/m³Thailand and Laos, March 2025
7 May 2026 16981.6 µg/m³–
24 Mar 2025 16574.8 µg/m³Thailand and Laos, March 2025
22 Apr 2025 16574.8 µg/m³–
13 Apr 2024 16170.2 µg/m³–
27 Mar 2025 16068.3 µg/m³Thailand and Laos, March 2025
25 Jan 2025 15967.5 µg/m³Northern Thailand, January 2025
4 Apr 2025 15966.7 µg/m³–
5 Apr 2025 15865.9 µg/m³–

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, Roi Et, Thailand, 1 Jan 2023 – 12 Oct 2026. Monitor data from Air4Thai via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/th/roi-et/history (accessed 12 Oct 2026).

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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.

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

Updated 2026-10-12 21:07 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).