SmogRank / Japan / Chiba / Katsuura
Katsuura, month by month
Katsuura has a measured daily mean on 855 days since 3 May 2024. Its worst month was July 2024, at 54 US AQI (10.7 µg/m³), 597th of 2,566 cities on that month's world ranking. Its cleanest was December 2024, at 22 US AQI (4.0 µg/m³).
Every month since 2024
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
Katsuura's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2024 | 5410.7 µg/m³ | 597thof 2,566 | – |
| August 2025 | 529.9 µg/m³ | 1,303rdof 3,095 | Japan, 25 to 27 August 2025 |
| July 2025 | 498.9 µg/m³ | 1,582ndof 3,073 | Japan and South Korea, June and July 2025 |
| April 2025 | 468.3 µg/m³ | 1,789thof 3,145 | – |
| July 2026 | 458.1 µg/m³ | 1,981stof 3,035 | – |
| March 2025 | 448.0 µg/m³ | 2,139thof 3,102 | Japan and South Korea, March 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.
Katsuura's worst days
| Day | US AQI | Episode |
|---|---|---|
| 25 Aug 2025 | 11742.0 µg/m³ | Japan, 25 to 27 August 2025 |
| 7 Jul 2025 | 11240.1 µg/m³ | Japan and South Korea, June and July 2025 |
| 6 Jul 2025 | 11239.8 µg/m³ | Japan and South Korea, June and July 2025 |
| 8 Jul 2025 | 9935.0 µg/m³ | Japan and South Korea, June and July 2025 |
| 26 Mar 2025 | 8627.9 µg/m³ | Japan and South Korea, March 2025 |
| 27 Mar 2025 | 7522.0 µg/m³ | Japan and South Korea, March 2025 |
| 4 Aug 2025 | 7521.9 µg/m³ | – |
| 30 Aug 2025 | 7321.0 µg/m³ | – |
| 4 Jul 2024 | 7119.7 µg/m³ | – |
| 9 Jul 2025 | 7119.6 µg/m³ | Japan and South Korea, June and July 2025 |
Daily means, the highest since 3 May 2024; 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, Katsuura, Japan, 3 May 2024 – 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/katsuura/history (accessed 14 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.
Katsuura now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-14 02:07 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).