SmogRank / Japan / Tochigi / Ashikaga
Ashikaga, month by month
Ashikaga has a measured daily mean on 942 days since 28 July 2023. Its worst month was July 2025, at 58 US AQI (12.7 µg/m³), 702nd of 2,889 cities on that month's world ranking. Its cleanest was September 2026, at 32 US AQI (5.7 µg/m³). 2025 averaged 51 US AQI (9.3 µg/m³), against 45 US AQI (8.1 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 | 14 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks. |
| Jan 2026 | 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 2025 | 15 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Nov 2025 | 20 of 30 days measured; a month needs 21. The others: 10 with under 18 hours of readings or readings that failed our checks. |
| Feb 2025 | 15 of 28 days measured; a month needs 20. The others: 13 with under 18 hours of readings or readings that failed our checks. |
| Jan 2025 | 12 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks. |
| Dec 2024 | 12 of 31 days measured; a month needs 22. The others: 19 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. |
| 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.
Ashikaga's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2025 | 5812.7 µg/m³ | 702ndof 2,889 | Japan and South Korea, June and July 2025 |
| July 2026 | 5812.6 µg/m³ | 791stof 2,784 | – |
| August 2025 | 5612.0 µg/m³ | 768thof 2,901 | Japan, 4 to 5 August 2025 |
| July 2024 | 5511.3 µg/m³ | 520thof 2,566 | – |
| November 2023 | 5310.1 µg/m³ | 600thof 2,243 | Japan, November 2023 |
| June 2025 | 5310.0 µg/m³ | 1,296thof 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.
Ashikaga's worst days
| Day | US AQI | Episode |
|---|---|---|
| 7 Jul 2025 | 10738.1 µg/m³ | Japan and South Korea, June and July 2025 |
| 8 Jul 2025 | 10336.5 µg/m³ | Japan and South Korea, June and July 2025 |
| 9 Jul 2025 | 9834.1 µg/m³ | Japan and South Korea, June and July 2025 |
| 5 Aug 2025 | 8728.5 µg/m³ | Japan, 4 to 5 August 2025 |
| 4 Nov 2023 | 8728.2 µg/m³ | Japan, November 2023 |
| 22 Jul 2026 | 7823.4 µg/m³ | – |
| 21 May 2025 | 7722.9 µg/m³ | – |
| 19 Apr 2025 | 7622.3 µg/m³ | – |
| 3 Nov 2023 | 7522.1 µg/m³ | Japan, November 2023 |
| 5 Nov 2023 | 7521.8 µg/m³ | Japan, November 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, Ashikaga, 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/ashikaga/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.
Ashikaga now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 22:07 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).