SmogRank / Japan / Ibaraki / Hitachi-Naka
Hitachi-Naka, month by month
Hitachi-Naka has a measured daily mean on 1,125 days since 28 July 2023. Its worst month was July 2024, at 57 US AQI (12.5 µg/m³), 360th of 2,566 cities on that month's world ranking. Its cleanest was January 2024, at 27 US AQI (4.9 µg/m³). 2025 averaged 46 US AQI (8.2 µg/m³), against 41 US AQI (7.3 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.
Hitachi-Naka's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2024 | 5712.5 µg/m³ | 360thof 2,566 | – |
| August 2025 | 5611.6 µg/m³ | 869thof 2,901 | Japan, 4 to 5 August 2025 |
| July 2025 | 5511.4 µg/m³ | 961stof 2,889 | Japan and South Korea, June and July 2025 |
| July 2026 | 5410.5 µg/m³ | 1,237thof 2,784 | Japan, July 2026 |
| April 2024 | 519.3 µg/m³ | 1,107thof 2,520 | Japan and South Korea, April 2024 |
| March 2025 | 498.9 µg/m³ | 1,796thof 2,862 | – |
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.
Hitachi-Naka's worst days
| Day | US AQI | Episode |
|---|---|---|
| 7 Jul 2025 | 11139.6 µg/m³ | Japan and South Korea, June and July 2025 |
| 8 Jul 2025 | 10035.2 µg/m³ | Japan and South Korea, June and July 2025 |
| 9 Jul 2025 | 9633.4 µg/m³ | Japan and South Korea, June and July 2025 |
| 20 Dec 2025 | 9030.0 µg/m³ | Japan, December 2025 |
| 5 Aug 2025 | 8829.0 µg/m³ | Japan, 4 to 5 August 2025 |
| 18 Apr 2024 | 8728.6 µg/m³ | Japan and South Korea, April 2024 |
| 16 Jul 2026 | 8427.0 µg/m³ | Japan, July 2026 |
| 6 Jul 2025 | 8225.5 µg/m³ | Japan and South Korea, June and July 2025 |
| 26 Mar 2025 | 7823.4 µg/m³ | – |
| 8 Jul 2024 | 7722.8 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, Hitachi-Naka, 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/hitachi-naka/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.
Hitachi-Naka 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).