SmogRank / Japan / Hokkaido / Chitose
Chitose, month by month
Chitose has a measured daily mean on 1,066 days since 28 July 2023. Its worst month was July 2024, at 57 US AQI (12.5 µg/m³), 360th of 2,566 cities on that month's world ranking. Its cleanest was August 2026, at 34 US AQI (6.2 µg/m³). 2025 averaged 51 US AQI (9.2 µg/m³), against 51 US AQI (9.2 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
4 months
| Month | Why |
|---|---|
| Sep 2025 | 14 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Jan 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. |
| Aug 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. |
| Jul 2023 | 4 of 31 days measured; a month needs 22. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Chitose's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2024 | 5712.5 µg/m³ | 360thof 2,566 | – |
| July 2025 | 5712.3 µg/m³ | 768thof 2,889 | – |
| June 2025 | 5712.2 µg/m³ | 774thof 2,508 | – |
| March 2026 | 5511.1 µg/m³ | 1,401stof 2,971 | Japan and South Korea, March 2026 |
| May 2025 | 5410.9 µg/m³ | 720thof 2,826 | – |
| October 2024 | 5310.2 µg/m³ | 509thof 2,020 | – |
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.
Chitose's worst days
| Day | US AQI | Episode |
|---|---|---|
| 30 Mar 2026 | 9231.3 µg/m³ | Japan and South Korea, March 2026 |
| 14 Feb 2024 | 9130.4 µg/m³ | Hokkaido and Aomori, Japan, February 2024 |
| 16 Jul 2024 | 8426.9 µg/m³ | – |
| 18 Jul 2024 | 8426.6 µg/m³ | – |
| 31 Mar 2026 | 8225.8 µg/m³ | Japan and South Korea, March 2026 |
| 29 Mar 2026 | 7823.8 µg/m³ | Japan and South Korea, March 2026 |
| 12 Jul 2024 | 7723.3 µg/m³ | – |
| 3 Jul 2025 | 7723.0 µg/m³ | – |
| 3 Jul 2024 | 7522.1 µg/m³ | – |
| 6 Nov 2025 | 7320.9 µg/m³ | – |
Daily means, the highest since 28 Jul 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, Chitose, Japan, 28 Jul 2023 – 12 Oct 2026. Monitor data from Ministry of the Environment Air Pollutant Wide Area Monitoring System via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/jp/chitose/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.
Chitose now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 17:07 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).