Air quality
Air quality in Sarnia today
Updated
Moderate (US AQI 53) Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors. Model estimate for Sun, Oct 25, 2:00 pm (18:00 UTC).
Live AQI, PM2.5, PM10 and ozone for Sarnia, Ontario, Canada, with a 48-hour forecast and the best time to be outside.
- US AQI now
- 53 Moderate
- PM2.5
- 8.7 µg/m³ 0.6× WHO 24-h guideline
- PM10
- 8.7 µg/m³
- Ozone
- 89 µg/m³
- Dominant pollutant
- PM2.5 sub-index 53
- Best hour today
- 2:00 pm AQI 53
- European AQI
- 35
Air quality in Sarnia right now
Right now the modelled US Air Quality Index for Sarnia, Ontario, Canada is 53, which falls in the "Moderate" band (up to 100). Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors.
The index is driven mainly by PM2.5, whose own sub-index is 53. Fine and coarse particles come from traffic, heating, industry, dust and smoke; they build up on calm nights and clear when wind or rain arrives.
PM2.5 is 8.7 µg/m³, within the WHO 24-hour guideline of 15 µg/m³; PM10 is 8.7 µg/m³ against a guideline of 45; ozone is 89 µg/m³ (below the WHO 8-hour level of 100); nitrogen dioxide is 11 µg/m³ (below the 24-hour guideline of 25).
Also this hour: UV index 2.8, carbon monoxide 207 µg/m³.
NASA FIRMS shows 182 fire hotspots within 300 km in the last day (nearest about 3 km), but particle levels are not elevated enough to point to smoke right now.
Sarnia AQI forecast: next 48 hours
Over the next 24 hours the AQI is forecast to range from 53 around Sun 2:00 pm to 64 around Mon 11:00 am, staying "Moderate" throughout.
The following day is expected to be cleaner, averaging about 48 against 58 for the next 24 hours.
| Local time (America/Toronto) | US AQI | Category | PM2.5 µg/m³ | PM10 µg/m³ | Ozone µg/m³ |
|---|---|---|---|---|---|
| Sun 2:00 pm | 53 | Moderate | 8.7 | 9 | 89 |
| Sun 5:00 pm | 54 | Moderate | 10 | 10 | 92 |
| Sun 8:00 pm | 54 | Moderate | 12.4 | 12 | 63 |
| Sun 11:00 pm | 55 | Moderate | 15 | 15 | 58 |
| Mon 2:00 am | 57 | Moderate | 17.9 | 18 | 50 |
| Mon 5:00 am | 59 | Moderate | 22.9 | 23 | 38 |
| Mon 8:00 am | 62 | Moderate | 26.5 | 27 | 30 |
| Mon 11:00 am | 64 | Moderate | 15 | 15 | 52 |
| Mon 2:00 pm | 63 | Moderate | 4 | 5 | 78 |
| Mon 5:00 pm | 62 | Moderate | 2.9 | 4 | 76 |
| Mon 8:00 pm | 60 | Moderate | 2.2 | 3 | 63 |
| Mon 11:00 pm | 57 | Moderate | 1.9 | 2 | 59 |
| Tue 2:00 am | 54 | Moderate | 1.9 | 2 | 56 |
| Tue 5:00 am | 49 | Good | 2.2 | 3 | 48 |
| Tue 8:00 am | 34 | Good | 2.5 | 3 | 39 |
| Tue 11:00 am | 21 | Good | 2.7 | 3 | 42 |
| Tue 2:00 pm | 20 | Good | 2.6 | 3 | 51 |
Every third hour of the CAMS forecast via Open-Meteo. US AQI uses rolling averages (24 h for particles, 8 h for ozone), so it moves more slowly than the hourly concentrations.
Best time to be outside in Sarnia today
Between 6 am and 9 pm local time, the cleanest air today is forecast around 2:00 pm (AQI 53, Moderate) and the worst around 5:00 pm (AQI 54). The difference across the day is small, so timing matters little.
Sarnia vs the rest of Canada
Across 78 Canada cities we track, the average US AQI right now is 43 (Good). Sarnia at 53 is 10 points worse than average.
It ranks 53 of 78 from cleanest to most polluted; the cleanest is Red Deer (21) and the most polluted Windsor (77).
For context, the median across 3,909 cities worldwide is 57.
Air quality in cities near Sarnia
| City | Distance | US AQI | Category | PM2.5 µg/m³ |
|---|---|---|---|---|
| Port Huron | 2 km | 53 | Moderate | 8.7 |
| Sterling Heights | 68 km | 77 | Moderate | 15.3 |
| Warren | 74 km | 77 | Moderate | 15.3 |
| Birmingham, MI | 82 km | 77 | Moderate | 15.3 |
| Pontiac | 82 km | 70 | Moderate | 14.4 |
| Ferndale | 83 km | 77 | Moderate | 15.3 |
| Waterford | 88 km | 66 | Moderate | 11.8 |
| Detroit | 89 km | 77 | Moderate | 15.3 |
Model vs measured
We found no measured PM2.5 sensor cell within 25 km of Sarnia, 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
At 53, most people are fine outdoors. If you are unusually sensitive to PM2.5, keep long or intense workouts to the cleaner hours shown above.
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 Sarnia
Air quality elsewhere
Data: Open-Meteo Air Quality API, Copernicus Atmosphere Monitoring Service (CAMS), NASA FIRMS.