SmogRank / Japan / Hiroshima / Onomichi
Onomichi, month by month
Onomichi has a measured daily mean on 1,102 days since 28 July 2023. Its worst month was July 2025, at 67 US AQI (17.7 µg/m³), 261st of 2,889 cities on that month's world ranking. Its cleanest was December 2024, at 34 US AQI (6.2 µg/m³). 2025 averaged 60 US AQI (13.8 µg/m³), against 48 US AQI (8.7 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
3 months
| Month | Why |
|---|---|
| Apr 2025 | 9 of 30 days measured; a month needs 21. The others: 21 with under 18 hours of readings or readings that failed our checks. |
| Feb 2024 | 17 of 29 days measured; a month needs 21. The others: 1 missing from OpenAQ's archive, 11 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.
Onomichi's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2025 | 6717.7 µg/m³ | 261stof 2,889 | Japan and South Korea, June and July 2025 |
| March 2026 | 6617.3 µg/m³ | 698thof 2,971 | Japan and South Korea, March 2026 |
| June 2025 | 6516.8 µg/m³ | 320thof 2,508 | Japan and South Korea, June and July 2025 Japan, June 2025 |
| February 2026 | 6416.3 µg/m³ | 719thof 2,866 | South Korea and Japan, 19 to 21 February 2026 South Korea and Japan, 10 to 15 February 2026and 1 more |
| March 2025 | 6315.7 µg/m³ | 881stof 2,862 | Japan and South Korea, March 2025 Japan and South Korea, February and March 2025 |
| May 2025 | 6215.1 µg/m³ | 400thof 2,826 | Japan, May 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.
Onomichi's worst days
| Day | US AQI | Episode |
|---|---|---|
| 2 Mar 2025 | 15967.2 µg/m³ | Japan and South Korea, February and March 2025 |
| 3 Jul 2025 | 15358.7 µg/m³ | Japan and South Korea, June and July 2025 |
| 4 Jul 2025 | 14854.7 µg/m³ | Japan and South Korea, June and July 2025 |
| 2 Jul 2025 | 11942.9 µg/m³ | Japan and South Korea, June and July 2025 |
| 28 Feb 2025 | 10938.9 µg/m³ | Japan and South Korea, February and March 2025 |
| 23 Jan 2025 | 10236.1 µg/m³ | Japan and South Korea, 17 to 24 January 2025 |
| 5 Jul 2025 | 9934.7 µg/m³ | Japan and South Korea, June and July 2025 |
| 29 Mar 2026 | 9834.4 µg/m³ | Japan and South Korea, March 2026 |
| 30 Mar 2026 | 9834.2 µg/m³ | Japan and South Korea, March 2026 |
| 24 Jan 2025 | 9834.1 µg/m³ | Japan and South Korea, 17 to 24 January 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, Onomichi, 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/onomichi/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.
Onomichi 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).