SmogRank / Finland / Uusimaa / Lohja

Lohja, month by month

Lohja has a measured daily mean on 873 days since 11 January 2023. Its worst month was March 2026, at 53 US AQI (10.1 µg/m³), 1,648th of 2,971 cities on that month's world ranking. Its cleanest was December 2024, at 17 US AQI (3.0 µg/m³).

Every month since 2023

202632 so far264 days measured2,524th of 2,793 in the world
Jan42#1,644Feb40#2,189Mar53#1,648Apr24#2,629May25#2,508Jun28#2,160Jul27#2,617Aug28#2,731Sep21#2,809Oct24#2,314
202529 for the year312 days measured2,488th of 2,681 in the world
Jan24#2,331Feb46#1,499Mar46#1,885Apr26#2,650May22#2,629Jun18 daysJul48#1,614Aug22#2,806Sep28#2,600Oct21#2,448Nov23#2,543Dec21#2,880
2024too few days for a mean (a year needs 257)241 days measured
Jan3 daysFeb24#2,258Mar15 daysApr24#2,143May30#2,178Jun23#2,366Jul25#2,368Aug13 daysSepnoneOct13 daysNov17#2,571Dec17#2,560
2023too few days for a mean (a year needs 256)56 days measured
Jan7 daysFeb28#1,063Mar20 daysApr3 daysMaynoneJunnoneJul1 dayAugnoneSepnoneOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Lohja'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 Lohja 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

17 months
MonthWhy
Jun 202518 of 30 days measured; a month needs 21. The others: 12 with under 18 hours of readings or readings that failed our checks.
Oct 202413 of 31 days measured; a month needs 22. The others: 18 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 202413 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks.
Mar 202415 of 31 days measured; a month needs 22. The others: 16 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.

Lohja's worst months

MonthUS AQIDays measuredWorld rankEpisode
March 2026 5310.1 µg/m³31 of 311,648thof 2,971Europe, 18 to 25 March 2026
Europe, 1 to 12 March 2026
July 2025 488.6 µg/m³30 of 311,614thof 2,889–
February 2025 468.3 µg/m³22 of 281,499thof 2,633Europe, 14 February to 1 March 2025
March 2025 468.3 µg/m³25 of 311,885thof 2,862Europe, 14 February to 1 March 2025
January 2026 427.5 µg/m³28 of 311,644thof 2,617–
February 2026 407.2 µg/m³26 of 282,189thof 2,866–

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.

Lohja's worst days

DayUS AQIEpisode
11 Mar 2026 10737.8 µg/m³Europe, 1 to 12 March 2026
24 Feb 2025 9331.9 µg/m³Europe, 14 February to 1 March 2025
25 Mar 2026 8225.8 µg/m³Europe, 18 to 25 March 2026
9 Mar 2026 7723.3 µg/m³Europe, 1 to 12 March 2026
12 Mar 2026 7622.3 µg/m³Europe, 1 to 12 March 2026
23 Feb 2025 7521.8 µg/m³Europe, 14 February to 1 March 2025
30 Mar 2025 7220.4 µg/m³–
16 Jan 2026 7120.0 µg/m³–
19 Feb 2026 6918.7 µg/m³–
10 Mar 2026 6818.4 µg/m³Europe, 1 to 12 March 2026

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, Lohja, Finland, 11 Jan 2023 – 12 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/fi/lohja/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.

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

Updated 2026-10-12 23:07 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).