SmogRank / Japan / Chiba / Sukayama
Sukayama, month by month
Sukayama has a measured daily mean on 1,136 days since 28 July 2023. Its worst month was July 2024, at 65 US AQI (16.8 µg/m³), 138th of 2,566 cities on that month's world ranking. Its cleanest was February 2025, at 32 US AQI (5.7 µg/m³). 2025 averaged 52 US AQI (9.9 µg/m³), against 52 US AQI (9.4 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
1 month
| Month | Why |
|---|---|
| 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.
Sukayama's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2024 | 6516.8 µg/m³ | 138thof 2,566 | Japan, 6 to 8 July 2024 |
| August 2025 | 5913.5 µg/m³ | 493rdof 2,901 | Chiba, Ibaraki and Yamanashi, Japan, August 2025 |
| July 2026 | 5611.8 µg/m³ | 929thof 2,784 | Japan and South Korea, July 2026 Japan, July 2026 |
| November 2025 | 5611.7 µg/m³ | 793rdof 2,715 | – |
| December 2025 | 5511.4 µg/m³ | 1,056thof 3,006 | Japan, December 2025 |
| February 2026 | 5511.4 µg/m³ | 1,114thof 2,866 | – |
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.
Sukayama's worst days
| Day | US AQI | Episode |
|---|---|---|
| 8 Jul 2025 | 10537.2 µg/m³ | Japan and South Korea, June and July 2025 |
| 7 Jul 2025 | 9633.4 µg/m³ | Japan and South Korea, June and July 2025 |
| 22 Jul 2026 | 9331.8 µg/m³ | Japan and South Korea, July 2026 |
| 30 Aug 2025 | 9130.4 µg/m³ | Chiba, Ibaraki and Yamanashi, Japan, August 2025 |
| 16 Jul 2026 | 8929.6 µg/m³ | Japan and South Korea, July 2026 Japan, July 2026 |
| 8 Jul 2024 | 8929.5 µg/m³ | Japan, 6 to 8 July 2024 |
| 7 Jul 2024 | 8728.5 µg/m³ | Japan, 6 to 8 July 2024 |
| 21 Nov 2025 | 8728.5 µg/m³ | – |
| 6 Jul 2024 | 8728.3 µg/m³ | Japan, 6 to 8 July 2024 |
| 20 Dec 2025 | 8728.2 µg/m³ | Japan, December 2025 |
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, Sukayama, 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/sukayama/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.
Sukayama 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).