Air quality in Longueuil, Quebec, Canada today

Mr. Duck’s Air Quality Score

Moderate air today for Longueuil, Quebec, Canada

⚠️ 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 Longueuil is currently classified as Moderate. The primary pollutant identified for today is PM2.5 (fine particles).

Measurements from OpenAQ show a PM2.5 concentration of 9.1 µg/m³, based on seven valid observations. This reflects the most recent data available 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

Longueuil’s open‑air quality feed currently includes seven measured variables: ozone (O3), fine particulate matter (PM2.5), coarse particles (PM10), ultrafine particles (PM1), relative humidity, temperature and particle concentration in the 0.003 µm range (UM003). The dataset is built from eight rows of sensor readings, but only two stations contribute recent data: one located at “Longueuil – Near Métro Station” and another reported simply as “Longueuil”. For most pollutants the latest update was on 2026‑02‑10 at 22:00 UTC; the PM10 reading is older, last refreshed on 2025‑01‑13 at 23:00 UTC.

The values show a narrow spread for several parameters. Ozone is constant at 0.032 ppm across all recent records, while relative humidity and temperature each sit at a single reported figure—48.16 % and 2.59 °C respectively—reflecting the limited temporal depth of the data. Particulate measurements display modest variation: PM2.5 ranges from about 6.23 to 9.10 µg/m³ with a median of 7.67 µg/m³, whereas PM1 and UM003 are reported as single points (3.33 µg/m³ and 627.74 particles/cm³). The older PM10 value is considerably higher at 47.47 µg/m³, but without recent updates its relevance to current conditions is uncertain.

Overall the dataset provides a snapshot rather than a continuous record; most pollutants have only one or two recent entries, and the proportion of old data (one row) exceeds that of fresh observations. Consequently, while the listed measurements give an overview of air‑quality components in Longueuil, they capture only limited moments in time and may not represent the full spatial or temporal variability across the city.

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 current dataset for Longueuil includes seven valid measurements and is marked as Updated within 3 days, with the latest values recorded on 2026‑02‑10 at 22:00 UTC. These figures represent a snapshot of conditions across the city; air quality can differ by specific location and time of day, so individual experiences may vary from the reported averages.

OpenAQ station rows