SmogRank / Finland / Uusimaa / Helsinki
Helsinki, month by month
Helsinki has a measured daily mean on 1,236 days since 1 January 2023. Its worst month was March 2026, at 54 US AQI (10.6 µg/m³), 1,515th of 2,971 cities on that month's world ranking. Its cleanest was December 2024, at 17 US AQI (3.1 µg/m³). 2025 averaged 34 US AQI (6.1 µg/m³), against 32 US AQI (5.7 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
5 months
| Month | Why |
|---|---|
| Jun 2025 | 20 of 30 days measured; a month needs 21. The others: 10 with under 18 hours of readings or readings that failed our checks. |
| Oct 2024 | 15 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Sep 2024 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2024 | 15 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | 15 of 31 days measured; a month needs 22. The others: 16 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.
Helsinki's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| March 2026 | 5410.6 µg/m³ | 1,515thof 2,971 | Europe, 18 to 25 March 2026 Europe, 1 to 12 March 2026 |
| July 2025 | 529.9 µg/m³ | 1,283rdof 2,889 | – |
| February 2025 | 478.5 µg/m³ | 1,456thof 2,633 | Europe, 14 February to 1 March 2025 |
| May 2024 | 468.2 µg/m³ | 1,238thof 2,684 | – |
| March 2025 | 468.2 µg/m³ | 1,901stof 2,862 | Europe, 14 February to 1 March 2025 |
| April 2023 | 458.1 µg/m³ | 803rdof 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.
Helsinki's worst days
| Day | US AQI | Episode |
|---|---|---|
| 24 Feb 2025 | 10537.1 µg/m³ | Europe, 14 February to 1 March 2025 |
| 11 Mar 2026 | 9633.4 µg/m³ | Europe, 1 to 12 March 2026 |
| 12 Mar 2026 | 8829.2 µg/m³ | Europe, 1 to 12 March 2026 |
| 25 Mar 2026 | 8527.5 µg/m³ | Europe, 18 to 25 March 2026 |
| 9 Mar 2026 | 8225.7 µg/m³ | Europe, 1 to 12 March 2026 |
| 1 Jun 2024 | 8024.4 µg/m³ | – |
| 17 Apr 2023 | 7622.5 µg/m³ | – |
| 10 Mar 2026 | 7622.3 µg/m³ | Europe, 1 to 12 March 2026 |
| 23 Feb 2025 | 7421.6 µg/m³ | Europe, 14 February to 1 March 2025 |
| 25 Mar 2025 | 7321.0 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, Helsinki, Finland, 1 Jan 2023 – 12 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/fi/helsinki/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.
Helsinki 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).