Air quality in Haarlem, North Holland, Netherlands today

Mr. Duck’s Air Quality Score

Moderate air today for Haarlem, North Holland, Netherlands

⚠️ This website is currently under active development. Some data may be incomplete or temporarily inaccurate. For health-critical decisions, please verify information through official government or environmental sources.

Categories follow US EPA AQI breakpoints for PM (estimate from latest valid measurements; this project does not compute EPA NowCast/24-hour AQI yet).

This friendly indicator summarizes the latest city readings. For health guidance, please see: EPA AirNow or WHO.

Air quality today

The air quality in Haarlem today is classified as Moderate. The primary pollutant identified is PM2.5 (fine particles). Measurements show a PM2.5 reference value of 34.23 µg/m³ and a PM10 reference value of 6.99 µg/m³, based on fourteen valid observations collected via OpenAQ.

These figures reflect the current monitoring results for the city. This page is informational; for health guidance, use official sources such as EPA AirNow or WHO.

Latest sensor values

PM categories follow US EPA AQI breakpoints, shown here as an estimate derived from the latest valid measurements (this project does not compute EPA NowCast/24-hour AQI yet).

What the data includes

The OpenAQ feed for Haarlem currently provides data on nine measured pollutants – nitrogen monoxide (NO), nitrogen dioxide (NO₂), ozone (O₃), particulate matter of three size fractions (PM1, PM2.5 and PM10), relative humidity, temperature and particle number concentration (UM003). The dataset contains 14 individual rows drawn from three monitoring stations, so each pollutant is not necessarily represented at every location. For the larger suite of pollutants (PM1, PM2.5, relative humidity, temperature and UM003) the most recent measurements were recorded on 2026‑02‑10 at 22:00 UTC, while the gas‑phase species (NO, NO₂ and O₃) were last updated an hour earlier, at 21:00 UTC on the same day. All timestamps fall within the past seven days, indicating that the data are fairly fresh overall.

Across the particulate metrics the observed values show a narrow spread. PM1 ranged from about 19.22 to 21.93 µg/m³ with a median of 20.57 µg/m³; PM2.5 varied between 32.91 and 34.23 µg/m³, median 33.57 µg/m³. The particle number concentration (UM003) exhibited the widest range, from roughly 979 to 3 208 particles/cm³, with a median near 2 093. Relative humidity stayed between 67.75 % and 69.10 %, median 68.43 %; temperature was confined to 11.78 °C–12.35 °C, median 12.06 °C. The gas‑phase readings are single‑value entries: NO at 2.56 µg/m³, NO₂ at 27.78 µg/m³ and O₃ at 16.07 µg/m³, each reported from the Haarlem‑Schipholweg station.

Because the dataset includes only three stations, spatial coverage within the city is limited; conditions can differ between neighbourhoods that are not directly monitored. Nevertheless, the recent timestamps mean the figures reflect the current state of the atmosphere in Haarlem as captured by these sensors.

Learn more about sources and filtering: About the data.

Trusted references: WHO (Air pollution) · US EPA AirNow · European Environment Agency (Air)

Latest sensor values (bars)

PM categories follow US EPA AQI breakpoints, shown here as an estimate derived from the latest valid measurements (this project does not compute EPA NowCast/24-hour AQI yet).

Data notes

The data shown for Haarlem are based on 14 valid measurements and have been updated within 3 days, with the latest refresh recorded at 2026‑02‑10T22:00:00+00:00. This snapshot reflects conditions at the time of collection; air quality can differ across neighborhoods and change throughout the day, so values may not represent every location or moment in the city.

OpenAQ station rows