SmogRank / Vietnam / Hanoi / Hanoi
Hanoi, month by month
Hanoi has a measured daily mean on 683 days since 1 January 2023. Its worst month was January 2025, at 169 US AQI (81.8 µg/m³), 14th of 2,474 cities on that month's world ranking. Its cleanest was July 2024, at 80 US AQI (24.4 µg/m³). 2024 averaged 121 US AQI (43.5 µg/m³), against 116 US AQI (41.6 µg/m³) in 2023.
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
24 months
| Month | Why |
|---|---|
| Sep 2026 | 1 of 30 days measured; a month needs 21. The others: 29 with under 18 hours of readings or readings that failed our checks. |
| Aug 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jun 2026 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| May 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Apr 2026 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Mar 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Feb 2026 | No day measured. The others: 28 with under 18 hours of readings or readings that failed our checks. |
| Jan 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Dec 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Nov 2025 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Oct 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2025 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jun 2025 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| May 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Apr 2025 | 9 of 30 days measured; a month needs 21. The others: 21 with under 18 hours of readings or readings that failed our checks. |
| Dec 2024 | 11 of 31 days measured; a month needs 22. The others: 20 with under 18 hours of readings or readings that failed our checks. |
| Aug 2024 | 7 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks. |
| Dec 2023 | 19 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Nov 2023 | 6 of 30 days measured; a month needs 21. The others: 24 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 9 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 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. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Hanoi's worst months
| Month | US AQI | World rank |
|---|---|---|
| January 2025 | 16981.8 µg/m³ | 14thof 2,474 |
| January 2023 | 16980.9 µg/m³ | 14thof 1,261 |
| November 2024 | 15967.0 µg/m³ | 16thof 2,624 |
| October 2024 | 14955.0 µg/m³ | 10thof 2,020 |
| March 2024 | 14653.8 µg/m³ | 8thof 1,698 |
| April 2023 | 13147.6 µg/m³ | 12thof 1,622 |
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.
Hanoi's worst days
| Day | US AQI |
|---|---|
| 20 Jan 2025 | 231156.0 µg/m³ |
| 5 Mar 2024 | 205130.0 µg/m³ |
| 21 Jan 2023 | 203128.0 µg/m³ |
| 19 Jan 2025 | 203128.0 µg/m³ |
| 18 Jan 2025 | 200125.0 µg/m³ |
| 10 Jan 2023 | 194117.0 µg/m³ |
| 26 Dec 2023 | 194117.0 µg/m³ |
| 10 Dec 2024 | 194117.0 µg/m³ |
| 8 Jan 2023 | 193116.0 µg/m³ |
| 30 Jan 2023 | 192114.0 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, Hanoi, Vietnam, 1 Jan 2023 – 12 Oct 2026. Monitor data from Spartan and Hanoi Air Quality Monitoring Network via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/vn/hanoi/history (accessed 12 Oct 2026). Contains readings from Vietnam's government monitors, no reuse terms published.
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.
Hanoi 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).