SmogRank / Thailand / Phayao / Phayao

Phayao, month by month

Phayao has a measured daily mean on 729 days since 1 January 2023. Its worst month was April 2026, at 182 US AQI (99.2 µg/m³), 7th of 2,941 cities on that month's world ranking. Its cleanest was September 2025, at 47 US AQI (8.4 µg/m³).

Every month since 2023

202694 so far253 days measured160th of 2,791 in the world
Jan86#197Feb90#255Mar154#47Apr182#7May70#290Jun55#547Jul3 daysAug52#997Sep53#636Oct58#336
2025too few days for a mean (a year needs 256)220 days measured
Jan5 daysFeb117#79Mar154#43Apr93#149May21 daysJun57#756JulnoneAug6 daysSep47#1,085Oct10 daysNov12 daysDec75#438
2024too few days for a mean (a year needs 257)183 days measured
Jan18 daysFeb144#22Mar18 daysApr164#8May99#55Jun53#601Jul17 daysAug18 daysSep5 daysOct2 daysNov3 daysDecnone
2023too few days for a mean (a year needs 256)73 days measured
Jan16 daysFeb1 dayMar6 daysApr17 daysMay14 daysJun11 daysJul3 daysAug2 daysSep3 daysOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Phayao'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 Phayao 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 202521 of 31 days measured; a month needs 22. The others: 10 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 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 202417 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks.
Mar 202418 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks.
Jan 202418 of 31 days measured; a month needs 22. The others: 13 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 202311 of 30 days measured; a month needs 21. The others: 19 with under 18 hours of readings or readings that failed our checks.
May 202314 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks.
Apr 202317 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 11 with under 18 hours of readings or readings that failed our checks.
Mar 20236 of 31 days measured; a month needs 22. The others: 19 missing from OpenAQ's archive, 6 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.
Jan 202316 of 31 days measured; a month needs 22. The others: 7 missing from OpenAQ's archive, 8 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.

Phayao's worst months

MonthUS AQIDays measuredWorld rankEpisode
April 2026 18299.2 µg/m³30 of 307thof 2,941Northern Thailand and Laos, April 2026
Northern Thailand and Laos, March and April 2026
April 2024 16474.0 µg/m³28 of 308thof 2,520Thailand and Laos, April and May 2024
March 2026 15460.3 µg/m³30 of 3147thof 2,971Northern Thailand and Laos, March and April 2026
March 2025 15459.9 µg/m³28 of 3143rdof 2,862–
February 2024 14453.0 µg/m³22 of 2922ndof 2,486–
February 2025 11742.1 µg/m³28 of 2879thof 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.

Phayao's worst days

DayUS AQIEpisode
7 Apr 2023 322236.0 µg/m³Northern Thailand and Laos around Bangkok, 5 to 8 April 2023
1 Apr 2023 280205.0 µg/m³Northern Thailand and Laos, March and April 2023
8 Apr 2023 261186.0 µg/m³Northern Thailand and Laos around Bangkok, 5 to 8 April 2023
26 Mar 2023 250175.0 µg/m³Northern Thailand and Laos, March and April 2023
2 Apr 2026 243168.0 µg/m³Northern Thailand and Laos, March and April 2026
27 Mar 2023 231156.0 µg/m³Northern Thailand and Laos, March and April 2023
29 Mar 2026 231156.0 µg/m³–
28 Mar 2023 227152.0 µg/m³Northern Thailand and Laos, March and April 2023
30 Mar 2026 226151.0 µg/m³–
5 Apr 2026 223148.0 µg/m³Northern Thailand and Laos, March and April 2026

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, Phayao, Thailand, 1 Jan 2023 – 12 Oct 2026. Monitor data from Air4Thai via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/th/phayao/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.

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

Updated 2026-10-12 19:07 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).