SmogRank / Japan / Miyagi / Shiroishi
Shiroishi, month by month
Shiroishi has a measured daily mean on 1,133 days since 28 July 2023. Its worst month was April 2024, at 61 US AQI (14.7 µg/m³), 424th of 2,520 cities on that month's world ranking. Its cleanest was December 2024, at 25 US AQI (4.5 µg/m³). 2025 averaged 50 US AQI (9.0 µg/m³), against 44 US AQI (7.9 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
2 months
| Month | Why |
|---|---|
| Mar 2024 | 12 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 18 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.
Shiroishi's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| April 2024 | 6114.7 µg/m³ | 424thof 2,520 | Japan and South Korea, April 2024 |
| March 2025 | 5712.5 µg/m³ | 1,156thof 2,862 | Japan and South Korea, March 2025 |
| March 2026 | 5712.2 µg/m³ | 1,175thof 2,971 | – |
| July 2025 | 5712.1 µg/m³ | 811thof 2,889 | – |
| May 2026 | 5511.0 µg/m³ | 656thof 2,874 | – |
| July 2026 | 5410.8 µg/m³ | 1,165thof 2,784 | – |
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.
Shiroishi's worst days
| Day | US AQI | Episode |
|---|---|---|
| 18 Apr 2024 | 15561.9 µg/m³ | Japan and South Korea, April 2024 |
| 26 Mar 2025 | 8628.1 µg/m³ | Japan and South Korea, March 2025 |
| 19 Apr 2024 | 8527.6 µg/m³ | Japan and South Korea, April 2024 |
| 17 Mar 2026 | 8326.2 µg/m³ | – |
| 17 Apr 2024 | 8326.1 µg/m³ | Japan and South Korea, April 2024 |
| 25 Mar 2025 | 7924.3 µg/m³ | Japan and South Korea, March 2025 |
| 14 Feb 2026 | 7823.7 µg/m³ | – |
| 9 Jul 2025 | 7823.4 µg/m³ | – |
| 19 Apr 2025 | 7723.3 µg/m³ | – |
| 14 Jul 2024 | 7622.3 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, Shiroishi, 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/shiroishi/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.
Shiroishi 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).