SmogRank / The Netherlands / North Holland / Wormer

Wormer, month by month

Wormer has a measured daily mean on 709 days since 1 January 2023. Its worst month was January 2026, at 66 US AQI (17.4 µg/m³), 605th of 2,617 cities on that month's world ranking. Its cleanest was April 2024, at 24 US AQI (4.4 µg/m³).

Every month since 2023

202649 so far220 days measured1,370th of 2,791 in the world
Jan66#605Feb62#785Mar56#1,234Apr33#2,210May29#2,220Jun16 daysJul16 daysAug28#2,749Sep28#2,284Oct7 days
2025too few days for a mean (a year needs 256)213 days measured
Jan3 daysFeb8 daysMar63#921Apr19 daysMay16 daysJun12 daysJul20 daysAug36#2,395Sep25#2,806Oct17 daysNov36#2,039Dec48#1,637
2024too few days for a mean (a year needs 257)166 days measured
Jan3 daysFeb2 daysMar10 daysApr24#2,143May48#1,094Jun34#1,967Jul27#2,287Aug14 daysSepnoneOct2 daysNov14 daysDec44#1,364
2023too few days for a mean (a year needs 256)110 days measured
Jan54#426Feb3 daysMar12 daysApr20 daysMay17 daysJun18 daysJul6 daysAug5 daysSep4 daysOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Wormer'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 Wormer 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

28 months
MonthWhy
Oct 20267 of 11 days measured; a month needs 8. The others: 4 with readings for part of the day (a day needs 18 hours).
Jul 202616 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
Jun 202616 of 30 days measured; a month needs 21. The others: 14 with under 18 hours of readings or readings that failed our checks.
Oct 202517 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks.
Jul 202520 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Jun 202512 of 30 days measured; a month needs 21. The others: 18 with under 18 hours of readings or readings that failed our checks.
May 202516 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
Apr 202519 of 30 days measured; a month needs 21. The others: 11 with under 18 hours of readings or readings that failed our checks.
Feb 20258 of 28 days measured; a month needs 20. The others: 20 with under 18 hours of readings or readings that failed our checks.
Jan 20253 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Nov 202414 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks.
Oct 20242 of 31 days measured; a month needs 22. The others: 29 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 202414 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks.
Mar 202410 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Feb 20242 of 29 days measured; a month needs 21. The others: 1 missing from OpenAQ's archive, 26 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 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 20235 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Jul 20236 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 24 with under 18 hours of readings or readings that failed our checks.
Jun 202318 of 30 days measured; a month needs 21. The others: 12 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.
Apr 202320 of 30 days measured; a month needs 21. The others: 3 missing from OpenAQ's archive, 7 with under 18 hours of readings or readings that failed our checks.
Mar 202312 of 31 days measured; a month needs 22. The others: 19 missing from OpenAQ's archive.
Feb 20233 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive.

A day counts once 18 hours of it are measured; a month needs 70% of its days.

Wormer's worst months

MonthUS AQIDays measuredWorld rankEpisode
January 2026 6617.4 µg/m³29 of 31605thof 2,617Europe, January and February 2026
March 2025 6315.3 µg/m³23 of 31921stof 2,862Europe, March 2025
Germany, Poland and 25 more countries, March 2025and 1 more
February 2026 6214.9 µg/m³26 of 28785thof 2,866Europe, January and February 2026
March 2026 5611.9 µg/m³31 of 311,234thof 2,971Europe, 18 to 25 March 2026
Europe, 1 to 12 March 2026
January 2023 5410.6 µg/m³25 of 31426thof 1,261France, The Netherlands and United Kingdom, January 2023
December 2025 488.7 µg/m³29 of 311,637thof 3,006–

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.

Wormer's worst days

DayUS AQIEpisode
25 Jan 2026 15662.7 µg/m³Europe, January and February 2026
5 Mar 2025 13850.5 µg/m³Germany, Poland and 25 more countries, March 2025
5 Feb 2026 12645.6 µg/m³Europe, January and February 2026
24 Jan 2026 12043.4 µg/m³Europe, January and February 2026
13 Feb 2025 11741.9 µg/m³Europe, 1 to 14 February 2025
10 Feb 2025 11139.5 µg/m³Europe, 1 to 14 February 2025
15 Feb 2023 10938.7 µg/m³Europe, 6 to 25 February 2023
6 Feb 2026 10537.3 µg/m³Europe, January and February 2026
25 Jan 2023 10436.7 µg/m³France, The Netherlands and United Kingdom, January 2023
23 Jan 2026 10135.5 µg/m³Europe, January and February 2026

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, Wormer, The Netherlands, 1 Jan 2023 – 11 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/nl/wormer/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.

Wormer 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).