SmogRank / Japan / Nagasaki / Iki
Iki, month by month
Iki has a measured daily mean on 1,143 days since 28 July 2023. Its worst month was April 2024, at 58 US AQI (12.9 µg/m³), 605th of 2,520 cities on that month's world ranking. Its cleanest was July 2024, at 19 US AQI (3.5 µg/m³). 2025 averaged 42 US AQI (7.6 µg/m³), against 40 US AQI (7.2 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.
Iki's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| April 2024 | 5812.9 µg/m³ | 605thof 2,520 | Japan and South Korea, April 2024 |
| March 2026 | 5310.2 µg/m³ | 1,848thof 3,285 | Japan and South Korea, March 2026 |
| January 2025 | 5310.0 µg/m³ | 1,226thof 2,754 | Japan and South Korea, 17 to 24 January 2025 |
| March 2024 | 529.4 µg/m³ | 516thof 1,698 | Japan, March 2024 |
| March 2025 | 519.2 µg/m³ | 1,940thof 3,102 | – |
| April 2026 | 519.1 µg/m³ | 1,355thof 3,307 | – |
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.
Iki's worst days
| Day | US AQI | Episode |
|---|---|---|
| 18 Apr 2024 | 12244.0 µg/m³ | Japan and South Korea, April 2024 |
| 19 Apr 2024 | 11340.2 µg/m³ | Japan and South Korea, April 2024 |
| 11 Feb 2024 | 11239.8 µg/m³ | Japan, 11 to 12 February 2024 |
| 21 Jan 2025 | 9834.2 µg/m³ | Japan and South Korea, 17 to 24 January 2025 |
| 28 Mar 2026 | 8426.7 µg/m³ | Japan and South Korea, March 2026 |
| 4 Mar 2024 | 8326.4 µg/m³ | Japan, March 2024 |
| 16 Jan 2026 | 8226.0 µg/m³ | South Korea and Japan, January 2026 |
| 22 Jan 2025 | 8225.8 µg/m³ | Japan and South Korea, 17 to 24 January 2025 |
| 28 Jul 2023 | 8125.2 µg/m³ | – |
| 29 Dec 2023 | 8125.0 µg/m³ | Japan, 29 to 31 December 2023 |
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, Iki, Japan, 28 Jul 2023 – 13 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/iki/history (accessed 13 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.
Iki now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 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).