SmogRank / Japan / Yamanashi / Yamanashi

Yamanashi, month by month

Yamanashi has a measured daily mean on 408 days since 28 July 2023. Its worst month was July 2026, at 57 US AQI (12.3 µg/m³), 843rd of 2,784 cities on that month's world ranking. Its cleanest was June 2026, at 37 US AQI (6.7 µg/m³).

Every month since 2023

2026too few days for a mean (a year needs 200)183 days measured
JannoneFeb4 daysMar9 daysApr48#1,355May47#1,183Jun37#1,589Jul57#843Aug19 daysSep19 daysOct47#1,006
2025too few days for a mean (a year needs 256)99 days measured
Jan6 daysFeb3 daysMar10 daysApr10 daysMay12 daysJun16 daysJul5 daysAug6 daysSep4 daysOct12 daysNov7 daysDec8 days
2024too few days for a mean (a year needs 257)93 days measured
Jan7 daysFeb9 daysMar13 daysApr12 daysMay6 daysJun9 daysJul10 daysAug5 daysSep3 daysOct6 daysNov11 daysDec2 days
2023too few days for a mean (a year needs 256)33 days measured
JanFebMarAprMayJunJul2 daysAug4 daysSep2 daysOct6 daysNov11 daysDec8 days
Each square is a month's mean PM2.5 in US AQI from Yamanashi's measured days, with its place on that month's world ranking under it. A month has a mean once 70% of its days are measured, the rule the monthly rankings use; under that, the square gives the days measured. Each square opens that month's ranking with Yamanashi marked; each year, the year's. A dashed square is the running month, so far.
Good0–50
Moderate51–100
Unhealthy for sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

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

35 months
MonthWhy
Sep 202619 of 30 days measured; a month needs 21. The others: 1 with readings for part of the day (a day needs 18 hours), 10 with under 18 hours of readings or readings that failed our checks.
Aug 202619 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Mar 20269 of 31 days measured; a month needs 22. The others: 22 with under 18 hours of readings or readings that failed our checks.
Feb 20264 of 28 days measured; a month needs 20. The others: 24 with under 18 hours of readings or readings that failed our checks.
Jan 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Dec 20258 of 31 days measured; a month needs 22. The others: 23 with under 18 hours of readings or readings that failed our checks.
Nov 20257 of 30 days measured; a month needs 21. The others: 23 with under 18 hours of readings or readings that failed our checks.
Oct 202512 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks.
Sep 20254 of 30 days measured; a month needs 21. The others: 26 with under 18 hours of readings or readings that failed our checks.
Aug 20256 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Jul 20255 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Jun 202516 of 30 days measured; a month needs 21. The others: 14 with under 18 hours of readings or readings that failed our checks.
May 202512 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks.
Apr 202510 of 30 days measured; a month needs 21. The others: 20 with under 18 hours of readings or readings that failed our checks.
Mar 202510 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Feb 20253 of 28 days measured; a month needs 20. The others: 25 with under 18 hours of readings or readings that failed our checks.
Jan 20256 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Dec 20242 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks.
Nov 202411 of 30 days measured; a month needs 21. The others: 19 with under 18 hours of readings or readings that failed our checks.
Oct 20246 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Sep 20243 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Aug 20245 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Jul 202410 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Jun 20249 of 30 days measured; a month needs 21. The others: 21 with under 18 hours of readings or readings that failed our checks.
May 20246 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Apr 202412 of 30 days measured; a month needs 21. The others: 18 with under 18 hours of readings or readings that failed our checks.
Mar 202413 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 17 with under 18 hours of readings or readings that failed our checks.
Feb 20249 of 29 days measured; a month needs 21. The others: 1 missing from OpenAQ's archive, 19 with under 18 hours of readings or readings that failed our checks.
Jan 20247 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks.
Dec 20238 of 31 days measured; a month needs 22. The others: 23 with under 18 hours of readings or readings that failed our checks.
Nov 202311 of 30 days measured; a month needs 21. The others: 19 with under 18 hours of readings or readings that failed our checks.
Oct 20236 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Sep 20232 of 30 days measured; a month needs 21. The others: 28 with under 18 hours of readings or readings that failed our checks.
Aug 20234 of 31 days measured; a month needs 22. The others: 27 with under 18 hours of readings or readings that failed our checks.
Jul 20232 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.

Yamanashi's worst months

MonthUS AQIDays measuredWorld rank
July 2026 5712.3 µg/m³29 of 31843rdof 2,784
April 2026 488.6 µg/m³30 of 301,355thof 2,941
May 2026 478.4 µg/m³31 of 311,183rdof 2,874
June 2026 376.7 µg/m³30 of 301,589thof 2,497

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.

Yamanashi's worst days

DayUS AQIEpisode
26 Mar 2025 13850.4 µg/m³Japan and South Korea, March 2025
19 Jan 2025 13348.6 µg/m³–
5 Aug 2025 12244.0 µg/m³Japan, 4 to 5 August 2025
5 Dec 2023 10135.5 µg/m³–
20 Dec 2025 9834.4 µg/m³–
6 Jan 2025 9633.5 µg/m³–
26 Nov 2024 9633.1 µg/m³–
18 Apr 2025 9432.3 µg/m³–
21 May 2025 9331.8 µg/m³Japan, May 2025
26 Aug 2025 9331.6 µg/m³Japan, 25 to 27 August 2025

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, Yamanashi, 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/yamanashi/history (accessed 13 Oct 2026).

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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.

Yamanashi now: the last 24 hours, its ranks today and the last 12 months day by day.

Updated 2026-10-13 04:07 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).