Air quality in Markham, Ontario, Canada today

Mr. Duck’s Air Quality Score

Good air today for Markham, 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 Markham today is classified as Good. The primary pollutant identified is PM2.5 (fine particles). Measurements show a PM2.5 concentration of 2.83 µg/m³ based on five valid observations reported through OpenAQ.

Overall conditions are favorable according to the available data, and no additional pollutants reached reporting thresholds. 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 Markham air‑quality feed includes five measured parameters from a single monitoring location in Unionville: PM1, PM2.5, relative humidity, temperature and particle count (UM003). All five rows are tied to the same station, so the dataset reflects conditions at one point rather than city‑wide coverage. Each pollutant record shows identical minimum, median and maximum values, indicating that only a single observation is currently available for each metric.

The most recent reading for every parameter was taken on 2026-02-10 12:00 UTC, meaning the data are fresh within the last three days as indicated by the source’s update flag. PM1 registers at 0.05283333361148834 µg/m³, while PM2.5 is measured at 2.8253333409627284 µg/m³. Relative humidity stands at 50.17316672007242 %, temperature is recorded as 2.4164999961853026 °C and the particle concentration (UM003) is 218.08283360799155 particles/cm³. Because each pollutant has only one data point, there is no spread or variability to describe; the reported values are both the minimum and maximum observed.

With just a single monitoring site contributing five rows of data, the picture of Markham’s air quality is necessarily limited in spatial scope. While the timestamps are recent, the lack of multiple stations means that conditions elsewhere in the city may differ from those captured at Unionville. Users should keep in mind that this snapshot provides a point‑in‑time view rather than a comprehensive overview of atmospheric conditions across Markham.

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 Markham includes five valid measurements and was refreshed recently, with the latest update recorded on 2026‑02‑10 at 12:00 UTC; it is considered “Updated within 3 days.” This snapshot reflects conditions at that time, but air quality can vary across different neighbourhoods and moments throughout the city.

OpenAQ station rows