Air quality in Guelph, Ontario, Canada today

Mr. Duck’s Air Quality Score

Moderate air today for Guelph, Ontario, 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 Guelph today is classified as Moderate. The primary pollutant identified for the current assessment is PM2.5 (fine particles).

Measurements from five valid monitoring stations show a PM2.5 concentration of 26.0 µg/m³, with no reference value reported for PM10. Data is shown via OpenAQ. 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 dataset for Guelph includes five measured pollutants – nitrogen monoxide (NO), nitrogen dioxide (NO₂), total nitrogen oxides (NOX), ozone (O₃) and fine particulate matter (PM2.5). All observations come from a single monitoring station, giving eight rows of data in total. The most recent reading for each pollutant was recorded on 2026-02-10 at 22:00 UTC, and every value is flagged as “Updated within 3 days,” indicating that the current snapshot reflects very recent conditions across the board.

Across the five pollutants the observed values show a narrow spread. NO₂ varies from a low of 0.002 ppm to a high of 0.010 ppm, with a median of 0.006 ppm and the 10th‑90th percentile range sitting between 0.0028 ppm and 0.0092 ppm. O₃ is similarly tight, ranging from 0.039 ppm to 0.049 ppm, median 0.044 ppm, with most readings clustered between 0.040 ppm and 0.048 ppm. PM2.5 values sit just above the 25 µg/m³ threshold, moving from 25.0 to 26.0 µg/m³; the median is 25.5 µg/m³ and the inter‑percentile band runs from 25.1 to 25.9 µg/m³. The nitrogen oxides are essentially constant: NO remains at 0.001 ppm, while NOX holds steady at 0.011 ppm for every record.

Because the data come from only one site, spatial coverage across Guelph is limited; conditions in other neighbourhoods may differ from what this single point measures. Nonetheless, the dataset provides a complete and up‑to‑date picture of the five key pollutants at the time of the latest update.

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 reflects five valid measurements and is updated within 3 days, with the most recent reading recorded on 2026‑02‑10 at 22:00 UTC. These values provide a snapshot of ambient conditions across Guelph, Ontario, but air quality can differ by neighbourhood and time of day, so local variations may not be captured in this summary.

OpenAQ station rows