SmogRank / Laos / Vientiane Prefecture / Vientiane
Vientiane, month by month
Vientiane has a measured daily mean on 1,133 days since 1 January 2023. Its worst month was April 2026, at 179 US AQI (95.1 µg/m³), 8th of 2,941 cities on that month's world ranking. Its cleanest was August 2024, at 42 US AQI (7.5 µg/m³). 2025 averaged 91 US AQI (30.8 µg/m³), against 81 US AQI (25.2 µg/m³) in 2024.
Every month since 2023
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
9 months
| Month | Why |
|---|---|
| Mar 2024 | 16 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks. |
| Feb 2024 | No day measured. The others: 1 missing from OpenAQ's archive, 28 with under 18 hours of readings or readings that failed our checks. |
| Jan 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Dec 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Nov 2023 | 18 of 30 days measured; a month needs 21. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Apr 2023 | 19 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 9 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 2 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive, 9 with under 18 hours of readings or readings that failed our checks. |
| Feb 2023 | 2 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. |
| Jan 2023 | 12 of 31 days measured; a month needs 22. The others: 7 missing from OpenAQ's archive, 12 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.
Vientiane's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| April 2026 | 17995.1 µg/m³ | 8thof 2,941 | Northern Thailand and Laos, April 2026 Northern Thailand and Laos, March and April 2026 |
| March 2025 | 16576.0 µg/m³ | 19thof 2,862 | Thailand and Laos, March 2025 |
| April 2024 | 16068.9 µg/m³ | 11thof 2,520 | Thailand and Laos, April and May 2024 |
| January 2026 | 15459.8 µg/m³ | 31stof 2,617 | – |
| January 2025 | 15358.8 µg/m³ | 23rdof 2,474 | – |
| March 2026 | 13850.5 µg/m³ | 83rdof 2,971 | Northern Thailand and Laos, March and April 2026 |
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.
Vientiane's worst days
| Day | US AQI | Episode |
|---|---|---|
| 6 Apr 2023 | 257182.0 µg/m³ | Northern Thailand and Laos around Bangkok, 5 to 8 April 2023 |
| 5 Apr 2026 | 243168.0 µg/m³ | Northern Thailand and Laos, March and April 2026 |
| 17 Apr 2026 | 236161.0 µg/m³ | Northern Thailand and Laos, April 2026 |
| 13 Apr 2026 | 232157.0 µg/m³ | Northern Thailand and Laos, April 2026 |
| 24 Mar 2025 | 229154.0 µg/m³ | Thailand and Laos, March 2025 |
| 6 Apr 2026 | 228153.0 µg/m³ | Northern Thailand and Laos, March and April 2026 |
| 25 Mar 2025 | 225150.0 µg/m³ | Thailand and Laos, March 2025 |
| 7 Apr 2023 | 221146.0 µg/m³ | Northern Thailand and Laos around Bangkok, 5 to 8 April 2023 |
| 4 Apr 2026 | 221146.0 µg/m³ | Northern Thailand and Laos, March and April 2026 |
| 16 Apr 2026 | 220145.0 µg/m³ | Northern Thailand and Laos, 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, Vientiane, Laos, 1 Jan 2023 – 12 Oct 2026. Monitor data from AirGradient via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/la/vientiane/history (accessed 12 Oct 2026).
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.
Vientiane now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 23:07 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).