SmogRank / Japan / Kanagawa / Ayase
Ayase, month by month
Ayase has a measured daily mean on 955 days since 28 July 2023. Its worst month was July 2024, at 69 US AQI (18.8 µg/m³), 114th of 2,566 cities on that month's world ranking. Its cleanest was September 2026, at 36 US AQI (6.4 µg/m³). 2025 averaged 54 US AQI (10.8 µg/m³), against 56 US AQI (11.6 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
10 months
| Month | Why |
|---|---|
| Mar 2026 | 21 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks. |
| Jan 2026 | 8 of 31 days measured; a month needs 22. The others: 23 with under 18 hours of readings or readings that failed our checks. |
| Dec 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. |
| Mar 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. |
| Feb 2025 | 9 of 28 days measured; a month needs 20. The others: 19 with under 18 hours of readings or readings that failed our checks. |
| Jan 2025 | 11 of 31 days measured; a month needs 22. The others: 20 with under 18 hours of readings or readings that failed our checks. |
| Dec 2024 | 9 of 31 days measured; a month needs 22. The others: 22 with under 18 hours of readings or readings that failed our checks. |
| Nov 2024 | 14 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Nov 2023 | 16 of 30 days measured; a month needs 21. The others: 14 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.
Ayase's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2024 | 6918.8 µg/m³ | 114thof 2,566 | Japan, 6 to 8 July 2024 |
| August 2025 | 6315.3 µg/m³ | 332ndof 2,901 | Japan, 25 to 27 August 2025 Japan, 4 to 5 August 2025 |
| July 2025 | 6014.1 µg/m³ | 491stof 2,889 | Japan and South Korea, June and July 2025 |
| April 2024 | 6013.7 µg/m³ | 514thof 2,520 | Japan and South Korea, April 2024 |
| July 2026 | 5813.1 µg/m³ | 712thof 2,784 | Japan, July 2026 |
| June 2025 | 5812.7 µg/m³ | 704thof 2,508 | Japan and South Korea, June and July 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.
Ayase's worst days
| Day | US AQI | Episode |
|---|---|---|
| 7 Jul 2025 | 15459.2 µg/m³ | Japan and South Korea, June and July 2025 |
| 8 Jul 2025 | 13850.5 µg/m³ | Japan and South Korea, June and July 2025 |
| 9 Jul 2025 | 12043.4 µg/m³ | Japan and South Korea, June and July 2025 |
| 4 Aug 2025 | 9934.8 µg/m³ | Japan, 4 to 5 August 2025 |
| 26 Mar 2025 | 9834.2 µg/m³ | Japan and South Korea, March 2025 |
| 6 Jul 2025 | 9834.2 µg/m³ | Japan and South Korea, June and July 2025 |
| 20 May 2025 | 9733.7 µg/m³ | Japan, May 2025 |
| 16 Jul 2026 | 9331.5 µg/m³ | Japan, July 2026 |
| 6 Jul 2024 | 9130.6 µg/m³ | Japan, 6 to 8 July 2024 |
| 26 Jun 2024 | 9030.2 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, Ayase, 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/ayase/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.
Ayase 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).