SmogRank / Norway / Trøndelag / Trondheim

Trondheim, month by month

Trondheim has a measured daily mean on 977 days since 1 January 2023. Its worst month was January 2026, at 56 US AQI (11.8 µg/m³), 937th of 2,617 cities on that month's world ranking. Its cleanest was September 2025, at 18 US AQI (3.3 µg/m³). 2025 averaged 26 US AQI (4.6 µg/m³), against 27 US AQI (4.9 µg/m³) in 2024.

Every month since 2023

2026too few days for a mean (a year needs 199)160 days measured
Jan56#937Feb49#1,730Mar32#2,563Apr26#2,570May26#2,484Jun25#2,229Jul2 daysAugnoneSepnoneOct1 day
202526 for the year299 days measured2,584th of 2,681 in the world
Jan32#2,066Feb27#2,415Mar23#2,643Apr27#2,609May22#2,600Jun22#2,399Jul39#1,982Aug21#2,831Sep18#3,036Oct9 daysNovnoneDec17 days
202427 for the year354 days measured1,960th of 2,097 in the world
Jan38#1,588Feb30#2,023Mar27#1,364Apr27#2,029May39#1,692Jun24#2,326Jul20#2,484Aug22#1,970Sep26#1,831Oct20#1,960Nov28#2,271Dec26#2,357
2023too few days for a mean (a year needs 256)164 days measured
Jan30#1,048Feb28#1,063Mar26#823Apr26#1,393May17 daysJun19 daysJul8 daysAug4 daysSep4 daysOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Trondheim'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 Trondheim marked; each year, the year's.
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

15 months
MonthWhy
Oct 20261 of 11 days measured; a month needs 8. The others: 10 with readings for part of the day (a day needs 18 hours).
Sep 2026No day measured. The others: 30 with readings for part of the day (a day needs 18 hours).
Aug 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 20262 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks.
Dec 202517 of 31 days measured; a month needs 22. The others: 14 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 20259 of 31 days measured; a month needs 22. The others: 22 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 20234 of 30 days measured; a month needs 21. The others: 26 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 20238 of 31 days measured; a month needs 22. The others: 23 with under 18 hours of readings or readings that failed our checks.
Jun 202319 of 30 days measured; a month needs 21. The others: 11 with under 18 hours of readings or readings that failed our checks.
May 202317 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.

Trondheim's worst months

MonthUS AQIDays measuredWorld rank
January 2026 5611.8 µg/m³26 of 31937thof 2,617
February 2026 498.8 µg/m³25 of 281,730thof 2,866
July 2025 397.1 µg/m³31 of 311,982ndof 2,889
May 2024 397.0 µg/m³31 of 311,692ndof 2,684
January 2024 386.8 µg/m³28 of 311,588thof 2,385
March 2026 325.8 µg/m³26 of 312,563rdof 2,971

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.

Trondheim's worst days

DayUS AQI
9 Oct 2026 8527.5 µg/m³
6 Jan 2026 8426.6 µg/m³
5 Jan 2026 8125.1 µg/m³
7 Feb 2026 7923.9 µg/m³
6 Feb 2026 7722.9 µg/m³
4 Jan 2026 7622.7 µg/m³
11 Jan 2026 7421.6 µg/m³
29 Jan 2026 7019.3 µg/m³
19 Jan 2026 7019.1 µg/m³
3 Feb 2026 6918.8 µg/m³

Daily means, the highest since 1 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, Trondheim, Norway, 1 Jan 2023 – 9 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/no/trondheim/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.

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

Updated 2026-10-12 19:07 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).