Air quality in Toronto, Ontario, Canada today

Mr. Duck’s Air Quality Score

Unhealthy for sensitive groups for Toronto, 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 overall air quality today is classified as USG. The main pollutant is PM2.5 (fine particles). The reference value for PM2.5 is 36.214 µg/m³ based on 56 valid measurements. Data is shown via OpenAQ.

This assessment reflects the concentration of fine particulate matter in the ambient air across Toronto. No PM10 value is available for this period. Measurements were gathered from multiple monitoring sites within the city. The snapshot includes only the PM2.5 measurement, as other pollutants were not reported for this time. All values are presented in micrograms per cubic meter. 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 Toronto air‑quality feed pulls data from 15 monitoring sites and currently holds 87 individual rows. Of those, 53 rows have been updated within the last 30 days while 34 are older than a month; no rows are marked as “today”, “last 3 days” or “last 7 days”. The most recent timestamp across the dataset is 2026‑02‑10 22:00 UTC. The collection includes measurements for PM2.5, PM1, O₃, NO₂, NO, relative humidity, temperature and the particle‑count metric UM003; the listed pollutants CO, NOX, PM10 and SO₂ do not have recent entries in this snapshot.

For the particulate matter series, the median PM2.5 concentration is 18 µg/m³ with values ranging from 0 µg/m³ up to 39.5 µg/m³; the 10th and 90th percentiles sit at roughly 0.19 µg/m³ and 30.7 µg/m³ respectively, indicating a broad spread around the central tendency. PM1 shows a median of 0.83 µg/m³ and a maximum of 25.1 µg/m³, with the 90th percentile near 25 µg/m³, suggesting that most low‑level readings cluster close to zero but occasional spikes occur. Temperature readings span from –6.5 °C to 31.3 °C with a median of 7.6 °C, while relative humidity varies between 39.4 % and 59.8 % (median 46.2 %). The UM003 particle count ranges widely from 24 to 3 374 particles/cm³, median 292, reflecting substantial variability in aerosol concentrations across sites.

Coverage across pollutants is uneven: O₃, NO₂ and NO each have fewer than ten recent rows (six, five and four respectively), whereas PM‑related metrics and meteorological variables have over ten rows each. This mix of recent and older observations means that city‑wide conditions can differ noticeably by location and time, and users should keep the timestamp distribution in mind when interpreting the numbers.

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 dataset includes 56 valid measurements and is updated within 30 days. The most recent data were recorded on 2026-02-10 at 22:00 UTC. This snapshot reflects conditions across Toronto, Ontario, Canada, but air quality can vary by location and time within the city. Users should consider these variations when interpreting the information.

OpenAQ station rows