SmogRank / Japan / Yamanashi / Ōtsuki
Ōtsuki, month by month
Ōtsuki has a measured daily mean on 1,118 days since 28 July 2023. Its worst month was August 2025, at 72 US AQI (20.3 µg/m³), 198th of 2,901 cities on that month's world ranking. Its cleanest was September 2026, at 22 US AQI (3.9 µg/m³). 2025 averaged 58 US AQI (12.7 µg/m³), against 55 US AQI (11.1 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
2 months
| Month | Why |
|---|---|
| Jan 2026 | 19 of 31 days measured; a month needs 22. The others: 12 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.
Ōtsuki's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| August 2025 | 7220.3 µg/m³ | 198thof 2,901 | Chiba, Ibaraki and Yamanashi, Japan, August 2025 Japan, 25 to 27 August 2025 |
| July 2025 | 7119.7 µg/m³ | 212thof 2,889 | Japan and South Korea, June and July 2025 |
| June 2025 | 6918.8 µg/m³ | 263rdof 2,508 | Japan and South Korea, June and July 2025 Japan, June 2025 |
| July 2024 | 6617.4 µg/m³ | 133rdof 2,566 | – |
| August 2024 | 6516.6 µg/m³ | 146thof 2,010 | – |
| May 2025 | 6215.2 µg/m³ | 396thof 2,826 | Japan, May 2025 |
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.
Ōtsuki's worst days
| Day | US AQI | Episode |
|---|---|---|
| 9 Jul 2025 | 11139.7 µg/m³ | Japan and South Korea, June and July 2025 |
| 26 Mar 2025 | 10436.9 µg/m³ | Japan and South Korea, March 2025 |
| 8 Jul 2025 | 10336.4 µg/m³ | Japan and South Korea, June and July 2025 |
| 7 Jul 2025 | 9834.5 µg/m³ | Japan and South Korea, June and July 2025 |
| 21 May 2025 | 9532.9 µg/m³ | Japan, May 2025 |
| 10 Jul 2025 | 9432.2 µg/m³ | Japan and South Korea, June and July 2025 |
| 25 Aug 2025 | 9030.0 µg/m³ | Japan, 25 to 27 August 2025 |
| 6 Jul 2024 | 8829.2 µg/m³ | – |
| 4 Aug 2025 | 8828.7 µg/m³ | – |
| 26 Jun 2024 | 8628.1 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, Ōtsuki, 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/otsuki/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.
Ōtsuki now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 18:07 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).