SmogRank / Japan / Okayama / Kasaoka
Kasaoka, month by month
Kasaoka has a measured daily mean on 1,126 days since 28 July 2023. Its worst month was April 2024, at 65 US AQI (16.7 µg/m³), 333rd of 2,520 cities on that month's world ranking. Its cleanest was September 2026, at 36 US AQI (6.4 µg/m³). 2025 averaged 56 US AQI (12.0 µg/m³), against 58 US AQI (12.7 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
2 months
| Month | Why |
|---|---|
| Jan 2024 | 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.
Kasaoka's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| April 2024 | 6516.7 µg/m³ | 333rdof 2,520 | Japan and South Korea, April 2024 |
| March 2025 | 6416.2 µg/m³ | 840thof 2,862 | Japan and South Korea, March 2025 Japan, March 2025and 1 more |
| July 2025 | 6416.2 µg/m³ | 325thof 2,889 | Japan and South Korea, June and July 2025 |
| June 2025 | 6416.1 µg/m³ | 363rdof 2,508 | Japan and South Korea, June and July 2025 Japan, June 2025 |
| June 2024 | 6315.7 µg/m³ | 187thof 2,563 | South Korea and Japan, June 2024 |
| November 2023 | 6315.5 µg/m³ | 139thof 2,243 | Okayama, Fukuoka and Hiroshima, Japan, November 2023 Japan, November 2023 |
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.
Kasaoka's worst days
| Day | US AQI | Episode |
|---|---|---|
| 4 Jul 2025 | 14754.1 µg/m³ | Japan and South Korea, June and July 2025 |
| 2 Mar 2025 | 14653.7 µg/m³ | Japan and South Korea, February and March 2025 |
| 3 Jul 2025 | 13348.5 µg/m³ | Japan and South Korea, June and July 2025 |
| 14 Feb 2024 | 12946.9 µg/m³ | Japan, 14 to 15 February 2024 |
| 18 Apr 2024 | 11541.1 µg/m³ | Japan and South Korea, April 2024 |
| 4 Nov 2023 | 11039.2 µg/m³ | Japan, November 2023 |
| 28 Feb 2025 | 10236.1 µg/m³ | Japan and South Korea, February and March 2025 |
| 23 Jan 2025 | 10235.8 µg/m³ | Japan and South Korea, 17 to 24 January 2025 |
| 1 Mar 2025 | 10135.5 µg/m³ | Japan and South Korea, February and March 2025 |
| 10 Dec 2023 | 9935.0 µg/m³ | Japan, 9 to 10 December 2023 |
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, Kasaoka, 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/kasaoka/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.
Kasaoka now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 20:07 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).