Air quality
Air quality in Markham today
Updated
Good (US AQI 50) Air quality is satisfactory and poses little or no risk; a good time for outdoor activity. Model estimate for Sun, Oct 25, 6:39 pm (22:39 UTC).
Live AQI, PM2.5, PM10 and ozone for Markham, Ontario, Canada, with a 48-hour forecast and the best time to be outside.
- US AQI now
- 50 Good
- PM2.5
- 10 µg/m³ 0.7× WHO 24-h guideline
- PM10
- 10 µg/m³
- Ozone
- 68 µg/m³
Air quality in Markham right now
Right now the modelled US Air Quality Index for Markham, Ontario, Canada is 50, which falls in the "Good" band (up to 50). Air quality is satisfactory and poses little or no risk; a good time for outdoor activity.
PM2.5 is 10 µg/m³, within the WHO 24-hour guideline of 15 µg/m³; PM10 is 10 µg/m³ against a guideline of 45; ozone is 68 µg/m³ (below the WHO 8-hour level of 100); nitrogen dioxide is 22 µg/m³ (below the 24-hour guideline of 25).
NASA FIRMS shows 88 fire hotspots within 300 km in the last day (nearest about 28 km), but particle levels are not elevated enough to point to smoke right now.
Markham vs the rest of Canada
Across 78 Canada cities we track, the average US AQI right now is 44 (Good). Markham at 50 is 6 points worse than average.
It ranks 46 of 78 from cleanest to most polluted; the cleanest is Lethbridge (25) and the most polluted Windsor (78).
For context, the median across 3,909 cities worldwide is 57.
Air quality in cities near Markham
| City | Distance | US AQI | Category | PM2.5 µg/m³ |
|---|---|---|---|---|
| Richmond Hill | 14 km | 38 | Good | 8.8 |
| Thornhill | 14 km | 38 | Good | 8.8 |
| Vaughan | 19 km | 38 | Good | 8.8 |
| Toronto | 21 km | 38 | Good | 8.8 |
| Aurora, ON | 22 km | 57 | Moderate | 8.2 |
| Whitby | 27 km | 41 | Good | 11.1 |
| Etobicoke | 35 km | 38 | Good | 8.8 |
| Mississauga | 45 km | 55 | Moderate | 9.1 |
Model vs measured
We found no measured PM2.5 sensor cell within 25 km of Markham, so the numbers on this page are model estimates. Models capture regional pollution well but can miss very local sources such as a busy road or a nearby fire.
Advice for sensitive groups
With the AQI at 50, there is no need for sensitive groups to change plans. People with asthma should still carry their reliever inhaler as usual.
What the US AQI numbers mean
| US AQI | Category | What it means |
|---|---|---|
| 0-50 | Good | Air quality is satisfactory and poses little or no risk; a good time for outdoor activity. |
| 51-100 | Moderate | Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors. |
| 101-150 | Unhealthy for Sensitive Groups | People with heart or lung disease, older adults, children and teens should cut back on prolonged or heavy exertion outdoors. |
| 151-200 | Unhealthy | Everyone should reduce prolonged or heavy exertion outdoors; sensitive groups should avoid it and keep windows closed. |
| 201-300 | Very Unhealthy | Health alert: everyone should avoid prolonged or heavy exertion outdoors, and sensitive groups should stay indoors. |
| 301-500 | Hazardous | Emergency conditions: everyone should avoid all outdoor physical activity and stay indoors with filtered air if possible. The scale tops out at 500; heavier dust or smoke is shown as 500. |
Values on this page are modelled by CAMS (Copernicus) and served by Open-Meteo; they are estimates for the area around the city centre, not readings from an official monitor.
Nearby cities
More for Markham
Air quality elsewhere
Data: Open-Meteo Air Quality API, Copernicus Atmosphere Monitoring Service (CAMS), NASA FIRMS.