SmogRank / France / Hauts-de-France / Boulogne-sur-Mer
Boulogne-sur-Mer, month by month
Boulogne-sur-Mer has a measured daily mean on 654 days since 11 January 2023. Its worst month was February 2025, at 74 US AQI (21.2 µg/m³), 475th of 2,633 cities on that month's world ranking. Its cleanest was September 2026, at 34 US AQI (6.2 µg/m³).
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
27 months
| Month | Why |
|---|---|
| Oct 2026 | 7 of 12 days measured; a month needs 9. The others: 3 with no readings from the monitor, 2 with readings for part of the day (a day needs 18 hours). |
| Jun 2026 | 18 of 30 days measured; a month needs 21. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Oct 2025 | 17 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks. |
| Jun 2025 | 18 of 30 days measured; a month needs 21. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| May 2025 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Apr 2025 | 7 of 30 days measured; a month needs 21. The others: 23 with under 18 hours of readings or readings that failed our checks. |
| Mar 2025 | 18 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks. |
| Oct 2024 | 13 of 31 days measured; a month needs 22. The others: 18 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 | 13 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks. |
| Jun 2024 | 2 of 30 days measured; a month needs 21. The others: 28 with under 18 hours of readings or readings that failed our checks. |
| May 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Apr 2024 | 2 of 30 days measured; a month needs 21. The others: 28 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | 10 of 31 days measured; a month needs 22. The others: 21 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 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Oct 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2023 | 1 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Jun 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| May 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Apr 2023 | No day measured. The others: 3 missing from OpenAQ's archive, 27 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | No day measured. The others: 20 missing from OpenAQ's archive, 11 with under 18 hours of readings or readings that failed our checks. |
| Feb 2023 | 4 of 28 days measured; a month needs 20. The others: 21 missing from OpenAQ's archive, 3 with under 18 hours of readings or readings that failed our checks. |
| Jan 2023 | 7 of 31 days measured; a month needs 22. The others: 14 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.
Boulogne-sur-Mer's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| February 2025 | 7421.2 µg/m³ | 475thof 2,633 | Europe, 14 February to 1 March 2025 Europe, 1 to 14 February 2025 |
| March 2026 | 6918.7 µg/m³ | 645thof 2,971 | Europe, 18 to 25 March 2026 Europe, 1 to 12 March 2026 |
| January 2025 | 6114.2 µg/m³ | 533rdof 2,474 | Germany, France and 19 more countries, January 2025 Western Europe, January 2025and 1 more |
| December 2024 | 5712.2 µg/m³ | 654thof 2,616 | Europe, 24 December 2024 to 3 January 2025 Europe, 12 to 14 December 2024 |
| December 2025 | 5511.2 µg/m³ | 1,091stof 3,006 | Europe, December 2025 to January 2026 |
| November 2024 | 5511.1 µg/m³ | 683rdof 2,624 | Europe, November 2024 |
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.
Boulogne-sur-Mer's worst days
| Day | US AQI | Episode |
|---|---|---|
| 5 Mar 2025 | 14352.5 µg/m³ | Germany, Poland and 25 more countries, March 2025 |
| 10 Mar 2025 | 13950.9 µg/m³ | Germany, Poland and 25 more countries, March 2025 |
| 23 Mar 2026 | 13850.7 µg/m³ | Europe, 18 to 25 March 2026 |
| 10 Feb 2025 | 12143.8 µg/m³ | Europe, 1 to 14 February 2025 |
| 7 Mar 2026 | 12043.1 µg/m³ | Europe, 1 to 12 March 2026 |
| 25 Mar 2025 | 11942.9 µg/m³ | Europe, March 2025 |
| 26 Jan 2026 | 11240.1 µg/m³ | Europe, January and February 2026 |
| 9 Mar 2026 | 11139.6 µg/m³ | Europe, 1 to 12 March 2026 |
| 8 Mar 2026 | 10738.1 µg/m³ | Europe, 1 to 12 March 2026 |
| 20 Mar 2026 | 10637.4 µg/m³ | Europe, 18 to 25 March 2026 |
Daily means, the highest since 11 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, Boulogne-sur-Mer, France, 11 Jan 2023 – 7 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/fr/boulogne-sur-mer/history (accessed 13 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.
Boulogne-sur-Mer now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 04:07 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).