Air quality in St. Catharines, Ontario, Canada today

Mr. Duck’s Air Quality Score

Moderate air today for St. Catharines, 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 St. Catharines today is classified as Moderate. The primary pollutant identified is PM2.5 (fine particles).

Measurements from five valid monitoring stations show a PM2.5 reference value of 10.0 µg/m³, with data displayed 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 St. Catharines air‑quality feed contains data for five measured pollutants – nitrogen monoxide (NO), nitrogen dioxide (NO2), total nitrogen oxides (NOX), ozone (O3) and fine particulate matter (PM2.5). The dataset comprises eight individual rows drawn from a single monitoring station, so the spatial coverage is limited to one location within the city. All of the most recent observations were recorded on 2026‑02‑10 at 22:00 UTC, meaning the freshest values are less than three days old for every pollutant.

Across the five compounds the observed concentrations span modest ranges. NO2 varies from a low of 0.003 ppm to a high of 0.011 ppm, with a median near 0.007 ppm; O3 shows a slightly broader spread, ranging between 0.029 and 0.042 ppm and centering around 0.036 ppm. PM2.5 values are measured in micrograms per cubic metre, from 10 µg/m³ up to 24 µg/m³, with the typical (median) reading at 17 µg/m³. The nitrogen monoxide and NOX readings are single‑value entries – both recorded at 0.001 ppm for NO and 0.011 ppm for NOX – reflecting that only one measurement was available for each of these gases.

Because the dataset relies on a solitary monitoring point, it captures conditions at that specific site but cannot represent citywide variation. The timestamps indicate all data are recent, yet the limited number of rows (eight) and the single‑station footprint mean many parts of St. Catharines may experience different pollutant levels at any given moment. Users should keep in mind that these figures provide a snapshot rather than a comprehensive picture of air quality across the entire urban area.

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 St. Catharines is based on five valid measurements and was updated within three days, with the most recent reading recorded at 2026‑02‑10T22:00:00+00:00. This snapshot reflects conditions at specific monitoring points and times; air quality can differ across neighborhoods and throughout the day, so values may not represent every location or moment in the city.

OpenAQ station rows