SmogRank / Japan / Hyōgo / Aioi
Aioi, month by month
Aioi has a measured daily mean on 762 days since 28 July 2023. Its worst month was July 2025, at 63 US AQI (15.7 µg/m³), 354th of 2,889 cities on that month's world ranking. Its cleanest was September 2026, at 32 US AQI (5.8 µg/m³).
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
18 months
| Month | Why |
|---|---|
| Dec 2024 | 14 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks. |
| Nov 2024 | 4 of 30 days measured; a month needs 21. The others: 26 with under 18 hours of readings or readings that failed our checks. |
| Oct 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2024 | 5 of 30 days measured; a month needs 21. The others: 25 with under 18 hours of readings or readings that failed our checks. |
| Aug 2024 | 6 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks. |
| Jul 2024 | 13 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks. |
| Jun 2024 | 10 of 30 days measured; a month needs 21. The others: 20 with under 18 hours of readings or readings that failed our checks. |
| May 2024 | 10 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks. |
| Apr 2024 | 15 of 30 days measured; a month needs 21. The others: 15 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | 9 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 21 with under 18 hours of readings or readings that failed our checks. |
| Feb 2024 | 3 of 29 days measured; a month needs 21. The others: 1 missing from OpenAQ's archive, 25 with under 18 hours of readings or readings that failed our checks. |
| Jan 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Dec 2023 | 5 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks. |
| Nov 2023 | 7 of 30 days measured; a month needs 21. The others: 23 with under 18 hours of readings or readings that failed our checks. |
| Oct 2023 | 8 of 31 days measured; a month needs 22. The others: 23 with under 18 hours of readings or readings that failed our checks. |
| Sep 2023 | 5 of 30 days measured; a month needs 21. The others: 25 with under 18 hours of readings or readings that failed our checks. |
| Aug 2023 | 4 of 31 days measured; a month needs 22. The others: 27 with under 18 hours of readings or readings that failed our checks. |
| Jul 2023 | 2 of 31 days measured; a month needs 22. The others: 2 with under 18 hours of readings or readings that failed our checks. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Aioi's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2025 | 6315.7 µg/m³ | 354thof 2,889 | Japan and South Korea, June and July 2025 |
| August 2025 | 6215.2 µg/m³ | 342ndof 2,901 | Japan, 25 to 27 August 2025 |
| June 2025 | 6215.0 µg/m³ | 443rdof 2,508 | Japan and South Korea, June and July 2025 |
| July 2026 | 6114.5 µg/m³ | 551stof 2,784 | Japan and South Korea, July 2026 |
| April 2025 | 5813.0 µg/m³ | 659thof 2,951 | Japan and South Korea, April 2025 |
| March 2025 | 5812.6 µg/m³ | 1,140thof 2,862 | Japan and South Korea, March 2025 Japan and South Korea, February and 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.
Aioi's worst days
| Day | US AQI | Episode |
|---|---|---|
| 5 Jul 2025 | 11641.6 µg/m³ | Japan and South Korea, June and July 2025 |
| 9 Jul 2025 | 11340.5 µg/m³ | Japan and South Korea, June and July 2025 |
| 4 Jul 2025 | 11340.2 µg/m³ | Japan and South Korea, June and July 2025 |
| 22 Jul 2026 | 10336.2 µg/m³ | Japan and South Korea, July 2026 |
| 23 Jan 2025 | 10236.1 µg/m³ | Japan and South Korea, 17 to 24 January 2025 |
| 2 Jul 2025 | 10235.8 µg/m³ | Japan and South Korea, June and July 2025 |
| 18 Apr 2024 | 9934.9 µg/m³ | Japan and South Korea, April 2024 |
| 23 Jul 2026 | 9934.9 µg/m³ | Japan and South Korea, July 2026 |
| 1 Mar 2025 | 9934.7 µg/m³ | Japan and South Korea, February and March 2025 |
| 3 Jul 2025 | 9733.9 µg/m³ | Japan and South Korea, June and July 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, Aioi, 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/aioi/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.
Aioi now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 19:07 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).