SmogRank / Italy / Aosta Valley / Aosta

Aosta, month by month

Aosta has a measured daily mean on 596 days since 11 January 2023. Its worst month was February 2023, at 67 US AQI (17.6 µg/m³), 212th of 1,129 cities on that month's world ranking. Its cleanest was May 2025, at 25 US AQI (4.5 µg/m³).

Every month since 2023

2026too few days for a mean (a year needs 199)180 days measured
Jan3 daysFebnoneMarnoneApr42#1,744May34#1,882Jun47#933Jul47#1,744Aug52#938Sep53#657Oct61#235
2025too few days for a mean (a year needs 256)178 days measured
JannoneFebnoneMar2 daysApr39#2,033May25#2,464Jun58#675Jul31#2,486Aug51#1,452Sep27#2,690Oct13 daysNovnoneDecnone
2024too few days for a mean (a year needs 257)182 days measured
Jan3 daysFeb57#436Mar13 daysApr33#1,711May25#2,365Jun39#1,661Jul47#1,174Aug15 daysSepnoneOct7 daysNovnoneDecnone
2023too few days for a mean (a year needs 256)56 days measured
Jan7 daysFeb67#212Mar20 daysApr3 daysMaynoneJunnoneJul1 dayAugnoneSepnoneOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Aosta'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 Aosta marked; each year, the year's. A dashed square is the running month, so far.
Good0–50
Moderate51–100
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

27 months
MonthWhy
Mar 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Feb 2026No day measured. The others: 28 with under 18 hours of readings or readings that failed our checks.
Jan 20263 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Dec 2025No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2025No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 202513 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks.
Mar 20252 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks.
Feb 2025No day measured. The others: 28 with under 18 hours of readings or readings that failed our checks.
Jan 2025No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Dec 2024No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 20247 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks.
Sep 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 202415 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks.
Mar 202413 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks.
Jan 20243 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Dec 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Sep 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 20231 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Jun 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
May 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Apr 20233 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Mar 202320 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Jan 20237 of 31 days measured; a month needs 22. The others: 14 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.

Aosta's worst months

MonthUS AQIDays measuredWorld rankEpisode
February 2023 6717.6 µg/m³25 of 28212thof 1,129Europe, 6 to 25 February 2023
June 2025 5812.9 µg/m³21 of 30675thof 2,508Europe, June 2025
February 2024 5712.5 µg/m³29 of 29436thof 2,486Italy, Switzerland and France, February 2024
September 2026 5310.0 µg/m³30 of 30657thof 2,981–
August 2026 529.8 µg/m³31 of 31938thof 2,896–
August 2025 519.1 µg/m³31 of 311,452ndof 2,901–

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.

Aosta's worst days

DayUS AQIEpisode
26 Sept 2026 11541.0 µg/m³–
22 Feb 2023 10336.2 µg/m³Europe, 6 to 25 February 2023
10 Jun 2025 10235.9 µg/m³Europe, June 2025
22 Feb 2024 9230.9 µg/m³Italy, Switzerland and France, February 2024
24 Feb 2023 9030.1 µg/m³Europe, 6 to 25 February 2023
8 Feb 2024 9029.8 µg/m³–
7 Feb 2024 8929.4 µg/m³–
9 Feb 2023 8829.1 µg/m³Europe, 6 to 25 February 2023
1 Oct 2026 8728.2 µg/m³–
23 Feb 2023 8627.8 µg/m³Europe, 6 to 25 February 2023

Daily means, the highest since 11 Jan 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, Aosta, Italy, 11 Jan 2023 – 11 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/it/aosta/history (accessed 12 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.

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

Updated 2026-10-12 18:07 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).