SmogRank / Japan / Hokkaido / Tomakomai
Tomakomai, month by month
Tomakomai has a measured daily mean on 1,113 days since 28 July 2023. Its worst month was July 2024, at 51 US AQI (9.2 µg/m³), 951st of 2,566 cities on that month's world ranking. Its cleanest was January 2026, at 24 US AQI (4.4 µg/m³). 2025 averaged 34 US AQI (6.1 µg/m³), against 34 US AQI (6.1 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
2 months
| Month | Why |
|---|---|
| Sep 2025 | 14 of 30 days measured; a month needs 21. The others: 16 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.
Tomakomai's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2024 | 519.2 µg/m³ | 951stof 2,566 | – |
| March 2026 | 468.3 µg/m³ | 2,060thof 2,971 | Japan and South Korea, March 2026 |
| November 2025 | 458.1 µg/m³ | 1,509thof 2,715 | – |
| July 2025 | 447.9 µg/m³ | 1,800thof 2,889 | – |
| May 2025 | 437.7 µg/m³ | 1,433rdof 2,826 | – |
| June 2025 | 427.5 µg/m³ | 1,920thof 2,508 | – |
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.
Tomakomai's worst days
| Day | US AQI | Episode |
|---|---|---|
| 31 Mar 2026 | 9432.1 µg/m³ | Japan and South Korea, March 2026 |
| 30 Mar 2026 | 8929.4 µg/m³ | Japan and South Korea, March 2026 |
| 14 Feb 2024 | 8527.2 µg/m³ | Hokkaido and Aomori, Japan, February 2024 |
| 3 Jul 2024 | 7321.0 µg/m³ | – |
| 5 Sept 2026 | 7120.0 µg/m³ | – |
| 16 Jul 2024 | 6919.0 µg/m³ | – |
| 12 Jul 2024 | 6818.1 µg/m³ | – |
| 18 Jul 2024 | 6717.7 µg/m³ | – |
| 13 Jul 2024 | 6416.0 µg/m³ | – |
| 6 Nov 2025 | 6416.0 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, Tomakomai, 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/tomakomai/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.
Tomakomai now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 21:07 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).