SmogRank / Japan / Aichi / Nishio
Nishio, month by month
Nishio has a measured daily mean on 1,050 days since 28 July 2023. Its worst month was March 2025, at 59 US AQI (13.3 µg/m³), 1,088th of 2,862 cities on that month's world ranking. Its cleanest was May 2024, at 37 US AQI (6.7 µg/m³). 2025 averaged 54 US AQI (10.7 µg/m³), against 44 US AQI (8.0 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
5 months
| Month | Why |
|---|---|
| Oct 2024 | 21 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks. |
| Feb 2024 | 19 of 29 days measured; a month needs 21. The others: 1 missing from OpenAQ's archive, 9 with under 18 hours of readings or readings that failed our checks. |
| Jan 2024 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Aug 2023 | 20 of 31 days measured; a month needs 22. The others: 11 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.
Nishio's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| March 2025 | 5913.3 µg/m³ | 1,088thof 2,862 | Japan and South Korea, March 2025 Japan, March 2025 |
| February 2026 | 5913.2 µg/m³ | 908thof 2,866 | – |
| August 2025 | 5812.8 µg/m³ | 606thof 2,901 | Japan, 4 to 5 August 2025 |
| April 2025 | 5712.4 µg/m³ | 716thof 2,951 | – |
| July 2026 | 5511.4 µg/m³ | 1,021stof 2,784 | Japan and South Korea, July 2026 |
| July 2025 | 5511.2 µg/m³ | 1,016thof 2,889 | 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.
Nishio's worst days
| Day | US AQI | Episode |
|---|---|---|
| 11 Nov 2025 | 15155.7 µg/m³ | – |
| 26 Mar 2025 | 13950.8 µg/m³ | Japan and South Korea, March 2025 |
| 9 Jul 2025 | 9432.3 µg/m³ | Japan and South Korea, June and July 2025 |
| 27 Mar 2025 | 9130.6 µg/m³ | Japan and South Korea, March 2025 Japan, March 2025 |
| 7 Jul 2025 | 9130.5 µg/m³ | Japan and South Korea, June and July 2025 |
| 5 Jul 2025 | 9130.4 µg/m³ | Japan and South Korea, June and July 2025 |
| 1 Feb 2025 | 9029.9 µg/m³ | Japan and South Korea, 31 January to 1 February 2025 |
| 8 Jul 2025 | 8829.0 µg/m³ | Japan and South Korea, June and July 2025 |
| 4 Nov 2023 | 8527.5 µg/m³ | Japan, November 2023 |
| 15 Oct 2024 | 8225.7 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, Nishio, 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/nishio/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.
Nishio 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).