SmogRank / World / Europe / The Netherlands / North Holland
Most polluted cities in North Holland, The Netherlands
8 measured cities, this year; 8 above the WHO annual guideline. Worst: Haarlem at 12.4 µg/m³, #694 in the world.
Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.
Cities coloured by their PM2.5 over the last 24 hours. Fires, smoke and ash: Oct 5, the newest UTC day mapped.
- 1Haarlemlow-cost sensors 10%
- 2Medemblik 3%
- 3Badhoevedorp 3%
- 4Wormerlast full day 1 Oct 2%
- 5Amsterdam 2%
- 6Velsen-Zuid 2%
- 7Zwanenburg 2%
- 8Zaanstad 2%
Low-cost sensors: consumer units, counted only in cities with no government-grade monitor; they read close to reference monitors on the whole, but 15 to 25% high in humid air. How we use them.
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
Estimated: cities without a monitor
North Holland cities we can't measure, with model estimates for the last 7 days. Listed by population, not ranked: estimates aren't precise enough to rank. Model estimates from the Copernicus Atmosphere Monitoring Service (CAMS), adjusted to measured cities nearby where there are any. Adjusted, a single day lands within ×1.5 of what a monitor would read about two times in three; unadjusted, it can be off by half or double. Treat them as a guide, not a measurement.
| City | 7-day estimate |
|---|---|
| Hoofddorp | ≈ 9 µg/m³ |
| Alkmaar | ≈ 7 µg/m³ |
| Hilversum | ≈ 9 µg/m³ |
| Purmerend | ≈ 9 µg/m³ |
| Amstelveen | ≈ 9 µg/m³ |
| Zaandam | ≈ 9 µg/m³ |
| Hoorn | ≈ 7 µg/m³ |
| Den Helder | ≈ 7 µg/m³ |
| Heerhugowaard | ≈ 7 µg/m³ |
| Huizen | ≈ 9 µg/m³ |
| Heemskerk | ≈ 9 µg/m³ |
| Beverwijk | ≈ 9 µg/m³ |
| Castricum | ≈ 9 µg/m³ |
| IJmuiden | ≈ 9 µg/m³ |
| Nieuw-Vennep | ≈ 9 µg/m³ |
| Bussum | ≈ 9 µg/m³ |
| Bergen | ≈ 7 µg/m³ |
| Uithoorn | ≈ 9 µg/m³ |
| Heemstede | ≈ 9 µg/m³ |
| Diemen | ≈ 9 µg/m³ |
| Assendelft | ≈ 9 µg/m³ |
| Heiloo | ≈ 7 µg/m³ |
| Aalsmeer | ≈ 9 µg/m³ |
| Volendam | ≈ 9 µg/m³ |
| Schagen | ≈ 7 µg/m³ |
| Weesp | ≈ 9 µg/m³ |
| Enkhuizen | ≈ 7 µg/m³ |
| Krommenie | ≈ 9 µg/m³ |
| Naarden | ≈ 9 µg/m³ |
| Zandvoort | ≈ 8 µg/m³ |
| Velserbroek | ≈ 9 µg/m³ |
| Julianadorp | ≈ 7 µg/m³ |
Bad-air episodes in North Holland
- Belgium, France and 2 more countries, June 202625 June 2026, 1 day15 cities39 µg/m³peak, Unna
- Europe, 18 to 25 March 20268 days430 cities136 µg/m³peak, Łask
- Europe, 1 to 12 March 202612 days532 cities109 µg/m³peak, Radomsko
- Europe, January and February 202612 January to 12 February 2026, 32 days625 cities252 µg/m³peak, Travnik
- Europe, December 2025 to January 202625 December 2025 to 2 January 2026, 9 days189 cities110 µg/m³peak, Kempten (Allgäu)
- Europe, 22 to 23 November 20252 days59 cities74 µg/m³peak, Żary
Times when many cities around here had PM2.5 at twice their usual or more on the same days.
Use this board
SmogRank, most polluted cities in North Holland, The Netherlands, PM2.5, this year to 6 Oct 2026, 23:00 UTC, smogrank.com/nl/region/north-holland?w=year.
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.
Updated 2026-10-06 23:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.